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Engine Fuel Pump Failure

jonweisw

Well Known Member
Adding a data point on this.

I have about 900h on my RV-8 with a Lyc IO360M1B, which was installed new with the airplane. Nine months ago, I upgraded my panel to dual G3x's from, among other things, the Grand Rapids EIS system.

At about the time that I was testing out my new avionics, I noticed occasional fluctuations in fuel pressure, from a baseline of about 24psi to momentary lows as much as 14-15psi. The dips were transient, occurring maybe once or twice per hour, and not associated with any changes in engine output, RPM/MP, or sound/tone. They seemed to happen at higher altitudes during prolonged cruise (6-9000'), but were not associated with temperature. There were no changes in fuel flow. Activating the Aux Fuel Pump remedied the low pressure without hesitation or fail. It is possible that this was occurring with the EIS system and that I missed it.

I decided to have the fuel pump replaced before it failed outright. Upon removal, there was nothing out of the ordinary; no debris, no leaks, no undue chaffing or obvious wear. I did not take the pump apart to inspect the diaphragm.

The new pump is generating 32-34psi consistently, hence confirming (to me at least) that the original pump was in slow failure mode.

I was under the impression that these pumps rarely fail.

Hope this helps someone in the future.

Jon Weiswasser
N898JW, RV-8
IO360M1B
 
Adding a data point on this.

I have about 900h on my RV-8 with a Lyc IO360M1B, which was installed new with the airplane. Nine months ago, I upgraded my panel to dual G3x's from, among other things, the Grand Rapids EIS system.

At about the time that I was testing out my new avionics, I noticed occasional fluctuations in fuel pressure, from a baseline of about 24psi to momentary lows as much as 14-15psi. The dips were transient, occurring maybe once or twice per hour, and not associated with any changes in engine output, RPM/MP, or sound/tone. They seemed to happen at higher altitudes during prolonged cruise (6-9000'), but were not associated with temperature. There were no changes in fuel flow. Activating the Aux Fuel Pump remedied the low pressure without hesitation or fail. It is possible that this was occurring with the EIS system and that I missed it.

I decided to have the fuel pump replaced before it failed outright. Upon removal, there was nothing out of the ordinary; no debris, no leaks, no undue chaffing or obvious wear. I did not take the pump apart to inspect the diaphragm.

The new pump is generating 32-34psi consistently, hence confirming (to me at least) that the original pump was in slow failure mode.

I was under the impression that these pumps rarely fail.

Hope this helps someone in the future.

Jon Weiswasser
N898JW, RV-8
IO360M1B

Same setup- YIO-360-M1B from Lycoming, now with just under 500 hours on it.

Mine will do this once in a very great while...like every few *months* it will do it, one time. I haven't been able to correlate it with anything whatsoever...not altitude, not RPM, not MAP, not angle of bank, pitch, fuel tank switching, nothing. It drops down to around 14 psi for a second or two (which trips the alarm and wakes me the f**k up in a hurry), then goes right back up to nominal 26-28 psi, and never moves again.

Maddening, but I have no idea what it could be or what to do about it. It's *definitely* in the data, and *not* a single data point glitch (collecting data at 4 Hz).
 
INTERESTING,

I have 722 hours on my Mattituck IO-360 and it has been doing the same thing since it was new three years ago. it usually generates 25 psi but dips to 20 intermittently and has become more frequent as of late.

I am in for conditional inspection now and will be replacing the engine driven pump in the process.

Did you replace with the genuine Lycoming or did you go with Tempest?

Anyone have any comments about brand preference?

:confused: CJ
 
I don't think it's a problem with the fuel pump. And I have the Kavlico transducers, so I doubt it's a problem there, although it could be, I guess. I rather suspect a very rare instance of cavitation at some point.

I'd rather not go changing the fuel pump for no reason, not only for the cost but also because I'm rather averse to "fixing" things without knowing if they're broken :).
 
fuel pump failure modes

If the fuel pump fails, are there any failure modes that would block fuel flow using the aux pump?
 
Adding a data point on this.

I have about 900h on my RV-8 with a Lyc IO360M1B, which was installed new with the airplane. Nine months ago, I upgraded my panel to dual G3x's from, among other things, the Grand Rapids EIS system.

At about the time that I was testing out my new avionics, I noticed occasional fluctuations in fuel pressure, from a baseline of about 24psi to momentary lows as much as 14-15psi. The dips were transient, occurring maybe once or twice per hour, and not associated with any changes in engine output, RPM/MP, or sound/tone. They seemed to happen at higher altitudes during prolonged cruise (6-9000'), but were not associated with temperature. There were no changes in fuel flow. Activating the Aux Fuel Pump remedied the low pressure without hesitation or fail. It is possible that this was occurring with the EIS system and that I missed it.

I decided to have the fuel pump replaced before it failed outright. Upon removal, there was nothing out of the ordinary; no debris, no leaks, no undue chaffing or obvious wear. I did not take the pump apart to inspect the diaphragm.

The new pump is generating 32-34psi consistently, hence confirming (to me at least) that the original pump was in slow failure mode.

I was under the impression that these pumps rarely fail.

Hope this helps someone in the future.

Jon Weiswasser
N898JW, RV-8
IO360M1B

I cant say for sure what happens when the fuel pressure drops bellow 14 psi on a 4cyl but I know when it drops below that on my 6 the engine is stumbling. Its unlikely your new pump is putting out 32 to 34 psi. I would suspect the transducer. Fuel pump failures happen but are rare.
Ryan
 
Has anyone with this problem, who replaced the pump, actually dissected it to see *for sure* if it was failing?

It's hard for me to understand how it could fail so intermittently in such a fashion...I'd think once the diaphragm started to fail (or whatever it is) that you'd see pressure drop *and stay there*.
 
Has anyone with this problem, who replaced the pump, actually dissected it to see *for sure* if it was failing?

It's hard for me to understand how it could fail so intermittently in such a fashion...I'd think once the diaphragm started to fail (or whatever it is) that you'd see pressure drop *and stay there*.

I did not dissect mine, but when it failed, it was an intermittent failure. The only time I had a low FP warning was in a nose up attitude at altitude. Pitch down by increasing speed and it resolved, slow down and pitch up, and it came back with no altitude change.
 
The reason I know it was a failure of the pump and NOT the transducer is that when the dips would occur they could be easily remedied by activating the electronic auxiliary fuel pump. The pressure would return to around 28 psi.

While I may not actually be getting 32-34psi from the new pump because the transducer hasn't been calibrated, it is worth noting that it is 10psi higher than it was reading nominally on the older pump (22psi) and there are no dips.

So, while it may not have truly hit 14psi in the dips (because the transducer wasnt calibrated), the mere fact that it was running half the pressure of what the aux pump could produce and that it was a departure by 40% of baseline was enough for me to change it out. Not worth waiting until complete failure IMO.
 
There is another thread now that is exploring the transducer possibility as an explanation that should be very interesting. In the meantime, here's a screenshot of a typical excursion (G3x data dump to saavy analysis)..

Screen_Shot_2018-01-28_at_7.06.11_PM.png
 
I?ve been seeing the same fuel pressure fluctuations on my g3x with my A1A as well. Engine runs fine so I?ve been ignoring it for now. Flipping on the boost pump bumps the pressure back up but engine never stumbles. I?ve seen fuel pressure drop while in the climb or while on the ground, it never straight and level flight
 
The reason I know it was a failure of the pump and NOT the transducer is that when the dips would occur they could be easily remedied by activating the electronic auxiliary fuel pump. The pressure would return to around 28 psi.

While I may not actually be getting 32-34psi from the new pump because the transducer hasn't been calibrated, it is worth noting that it is 10psi higher than it was reading nominally on the older pump (22psi) and there are no dips.

So, while it may not have truly hit 14psi in the dips (because the transducer wasnt calibrated), the mere fact that it was running half the pressure of what the aux pump could produce and that it was a departure by 40% of baseline was enough for me to change it out. Not worth waiting until complete failure IMO.

I'm not trying to be disagreeable, only to apply engineering methodology here...all you know is that when you turned on the auxiliary pump, the pressure as indicated went back up. The transducer could have a failure mode that makes it non-linear in response, the auxiliary pump could clear another fault somewhere in the line, etc.

Unless you have a *root* cause of the failure, you don't know for sure what caused the drops...
 
There is another thread now that is exploring the transducer possibility as an explanation that should be very interesting. In the meantime, here's a screenshot of a typical excursion (G3x data dump to saavy analysis)..

Screen_Shot_2018-01-28_at_7.06.11_PM.png

This has a very similar profile to the excursions I've seen...steep drop for the initial portion, slightly less steep after that, minimum, then rapid climb back up to normal. This looks slightly longer in duration than the ones I've seen, though, which are on the order of just a handful of seconds.

I'll try to find one to post an image, but as I said, it's rare enough (3-6 months between them on average) that it'll take me a while to find one.

BTW, I've seen them in stabilized, straight and level flight, not correlated to pitch or roll changes, switching tanks, or turning on/off the boost pump.
 
Never had a Lycoming pump fail! That is with 6000 plus hours of owing 20+ (Only 16 had lycomings) airplanes. Only mechanical pump I ever had fail, was on a Rotax 912, there was a service letter about this particular pump, saying it was prone to problems, and it did have that problem.
 
Check out your Lycoming Engine Operators Manual. Your engine should put out max 35 psi to a minimum -2 psi. That's negative 2 psi. So the issue is not fuel pressure but fuel flow. As long as there is a fuel flow reading it will run. I've seen this many times with these engines and don't have answer except for maybe air in the line. I don't have this issue with the RV7 because the pressure reading is taken at the outlet of the fuel pump instead of the flow divider. I've had two pump failures, about 3 years ago in a PA28-140 and several years ago in a PA28R-200, both times on take off. I didn't know about it until I turned off the electric pump. The 140 had about 300 hours on the pump and the Arrow was a fairly new airplane. Just make sure you have a good electric pump. There are AD's on these pumps and life limits on them as well. I don't think you have an issue but it can usually be fixed if you shut off the engine and wait an few minutes then start it up you will get a better reading.
 
Check out your Lycoming Engine Operators Manual. Your engine should put out max 35 psi to a minimum -2 psi. That's negative 2 psi. So the issue is not fuel pressure but fuel flow. As long as there is a fuel flow reading it will run. I've seen this many times with these engines and don't have answer except for maybe air in the line. I don't have this issue with the RV7 because the pressure reading is taken at the outlet of the fuel pump instead of the flow divider. I've had two pump failures, about 3 years ago in a PA28-140 and several years ago in a PA28R-200, both times on take off. I didn't know about it until I turned off the electric pump. The 140 had about 300 hours on the pump and the Arrow was a fairly new airplane. Just make sure you have a good electric pump. There are AD's on these pumps and life limits on them as well. I don't think you have an issue but it can usually be fixed if you shut off the engine and wait an few minutes then start it up you will get a better reading.

These are the numbers I see in the manual:

O-360 Series (Except -A1C, -C2B,
-C2D); HO-360-A, -C Series
Inlet to carburetor; Max: 8.0 Desired: 3.0 Min: 0.5

IO-360 Series (Except -B1A),
AIO-360 Series; HIO-360 Series
Inlet to fuel injector Max: 45 Min:14
 
What edition or dated version are you looking at? The latest hard copy I have is the 8th Edition dated October 2005. I'm pretty sure that is same as the current version but I no longer have access to it as of Nov 2017.
 
Im looking at the 8th Edition dated Oct 2005 revision Dec 2009. I believe that is the latest revision but I don't have access to that any more as of Nov 2017. I looking at the inlet to the fuel pump not the injector. Some of my previous post should be disregarded. Thanks for the clarification Walt.
 
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I have a new Tempest pump on order right now. The original Lycoming pump began squeezing oil out along the topmost diaphragm clamp line. I easily tightened the screws a 1/4 turn or more, but when inspecting a few hours later I realized it is also weeping oil from the relief tube. The upper oil diaphragm seems to be failing.
 
All interesting replies and thank you all for the interest!

True that 14psi is considered 'normal' according to the lycoming manual; alternatively, I would argue that you don't really know exactly what the pressure is because the transducer is not calibrated. What I did observe is that there was a transient change in the pressure that was alarming. This change was rectified by boost pump and ultimately by replacement. I don't buy that 'simple mechanical pumps don't fail'. That seems like wishful thinking to me.

Yet, I also agree that given that I didn't pinpoint a physical fault in the pump by disassembling it after removing it, I cannot say with 100% certainty that the pump is the culprit. However, given the choice of replacing a transducer (cheaper, non-critical) versus a pump (more expensive, critical), I am going to replace the critical component, especially because they aren't THAT expensive and the full failure of it could be problematic from a safety point of view (unlike a transducer).

If faced with the same situation tomorrow, I would do the same.
 
All interesting replies and thank you all for the interest!

True that 14psi is considered 'normal' according to the lycoming manual; alternatively, I would argue that you don't really know exactly what the pressure is because the transducer is not calibrated. What I did observe is that there was a transient change in the pressure that was alarming. This change was rectified by boost pump and ultimately by replacement. I don't buy that 'simple mechanical pumps don't fail'. That seems like wishful thinking to me.

I don't think anybody said that. I think they said that it's *unlikely*.

Yet, I also agree that given that I didn't pinpoint a physical fault in the pump by disassembling it after removing it, I cannot say with 100% certainty that the pump is the culprit. However, given the choice of replacing a transducer (cheaper, non-critical) versus a pump (more expensive, critical), I am going to replace the critical component, especially because they aren't THAT expensive and the full failure of it could be problematic from a safety point of view (unlike a transducer).

Now we get to the interesting part...you don't *know* what is happening to cause the intermittent fluctuation, and you are removing and replacing critical components. I will direct your attention to the well-known Waddington Effect.

I don't even think that I'd start by replacing the transducer unless I knew it was failing or always wrong.

Bottom line...you replaced a part that you didn't know was bad, with a new part that might not fix the problem, because you don't know what the actual problem is in the first place. To top it off, you've messed with a critical system, thus poking the ghost of Waddington who demonstrated that most failures occur in the hours after significant maintenance.

If faced with the same situation tomorrow, I would do the same.

Well, you might be...if the pump wasn't the problem.
 
But it did fix the problem!

I am surprised by the resistance here. Sorry.... Im not going to let something that is a critical component and is acting up just go ahead and fail if I can help it. Waddington effect or not. This seems like common sense to me.

I will try to fish out the old pump and take it apart to see if this can shed any more light on this. I was certainly NOT going to disassemble the pump and NOT replace it.

Unlikely or not, what was causing the pressure fluctuation was the old pump. Fortunately it had no consequence. The new pump is functioning as a new pump should.
 
Since we're discussing fuel pressure, I would like to ask another question. I have a Lycoming IO-360, with a Dynon Skyview and Kavlico sensor. Since very first engine start, displayed fuel pressures fluctuate between low 20's, to medium-to-high 20's, while in cruise. I tapped the fuel pressure sensor line into the main fuel line at the fitting coming out of the mechanical fuel pump. The tap fitting has a restricted orifice (unfortunitly I can't recall the diameter, likely down around #55 drill size). Later, I added another restriction at the fitting entering the Kavlico, which helped, but did not solve the fluctuations.
Any suggestions? Maybe go even smaller orifice diameters? Any suggestion on how small I should go?
Thanks for any input/suggestions.
 
Since we're discussing fuel pressure, I would like to ask another question. I have a Lycoming IO-360, with a Dynon Skyview and Kavlico sensor. Since very first engine start, displayed fuel pressures fluctuate between low 20's, to medium-to-high 20's, while in cruise. I tapped the fuel pressure sensor line into the main fuel line at the fitting coming out of the mechanical fuel pump. The tap fitting has a restricted orifice (unfortunitly I can't recall the diameter, likely down around #55 drill size). Later, I added another restriction at the fitting entering the Kavlico, which helped, but did not solve the fluctuations.
Any suggestions? Maybe go even smaller orifice diameters? Any suggestion on how small I should go?
Thanks for any input/suggestions.

If you have any air in the line, that can cause fluctuations. Have you bled the line to the sender recently, or before first start even?

Chris
 
Years ago when we got the Cozy MKIV flying with a brand new Superior IO-360 engine, the fuel pressure started acting up in the early stages of Phase 1 to the point the test pilot declared an emergency on climb out. The engine still ran but would not develop full power and the return to field and landing was uneventful. After thorough discussions with Superior and data transfer to them, they felt that the mechanical fuel pump was bad and sent out a new one under warranty. Problem solved. FWIW.
 
But it did fix the problem!

I am surprised by the resistance here. Sorry.... Im not going to let something that is a critical component and is acting up just go ahead and fail if I can help it. Waddington effect or not. This seems like common sense to me.

Unlikely or not, what was causing the pressure fluctuation was the old pump. Fortunately it had no consequence. The new pump is functioning as a new pump should.

Just for the record I think you did the right thing, some folks prefer getting a** deep into the theory behind every little problem. Like you said, it was not that big a deal to replace the pump and it was the most likely cause of your problem, good for you, pro-active mantenance IMO.

Maintenance must be done regardless of the "waddington effect", perhaps some folks like to use that as a reason not to do stuff :confused:
 
....Bottom line...you replaced a part that you didn't know was bad, with a new part that might not fix the problem, because you don't know what the actual problem is in the first place. To top it off, you've messed with a critical system, thus poking the ghost of Waddington who demonstrated that most failures occur in the hours after significant maintenance....

If I remember right, The Waddington Effect found that the incidence of defects increased after scheduled maintenance, and gradually reduced as those problems were fixed. But then came another regularly scheduled maintenance and the situation repeated. The amount of operational aircraft increased when maintenance that had been performed on time intervals was changed to occur upon condition. While failures indeed occurred after maintenance, nothing from his work said not to do maintenance upon failure, just don't do it arbitrarily. Mr. Conrad Waddington can rest easily.

This situation is quite clearly not a regularly scheduled maintenance-related problem. Instead, it occurred and we didn't know why.

One of the recognized and common methods of determining what is at fault in a complex multi-part system is to remove and replace a single component and see what the effect is. We all learned how to do that in general, when we were taught the very valuable technique of making a hypothesis and devising a test that checks it. If done correctly, that gives us some data. If done especially nicely, it gives us limited data that can only have one conclusion.

In this case this is exactly what Jon did: he first determined that turning on the boost pump eliminated the apparent fault. This tended to suggest that the transducer was probably operating correctly, tending to eliminate that potential failure mode. He replaced the mechanical fuel pump (successfully, thus not creating an example of the Waddington Effect while so doing) and flew again. This time the problem was eliminated. And that was all he needed to do to resolve it.

Bottom line, Walt's right.

Please note that the mechanical pump replacement also eliminated another unknown potential problem, that some issue with the boost pump could be creating fuel pressure issues when the boost pump was off. If it had, replacing the mechanical pump wouldn't have affected the symptoms. But now we know that the boost pump is okay.

It might be interesting to open up the old pump and see what was going on with it, but that's not germane to the repair itself. I'd think that a better thing to do with it is see if the manufacturer would like to have it back to do that themselves. That way they could make improvements if any seem necessary.

Dave
 
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Just for the record I think you did the right thing, some folks prefer getting a** deep into the theory behind every little problem. Like you said, it was not that big a deal to replace the pump and it was the most likely cause of your problem, good for you, pro-active mantenance IMO.

Maintenance must be done regardless of the "waddington effect", perhaps some folks like to use that as a reason not to do stuff :confused:

I respect you, Walt, but I think that's a little unfair. I'm not advocating avoiding proper maintenance and troubleshooting, not at all. I'm only saying that I, personally, would not start replacing parts unless and until I a) had a good working theory of the cause, and b) could analyze or test the theory. How many posts have we seen on here where people had a laundry list of things that they *replaced* which didn't solve the underlying problem?

Replacing the pump is fine, but I would then try determine if it was *actually* failing...perhaps by bench testing, then disassembly, etc. Otherwise, I'd always have that little voice in the back of my head saying "what it that wasn't it?" That's why I'm still watching my (every 6 months or so) FP excursions, in the hopes of identifying a root cause.

Maybe it's the aerospace engineer in me, I dunno, but I *always* want to find the ultimate root cause(s). :)

To the other poster, yes, Waddington found his effect relative to *scheduled* maintenance, so it's not entirely the same thing, but we do know that fixing something that isn't actually broken does introduce additional risks (improper reassembly, primarily).

On-condition vs. scheduled maintenance is an interesting topic...I've seen scheduled maintenance (mandated by vendors/suppliers) that resulted in some *very* expensive downtimes for some seriously complex, critical equipment because of precisely this effect.
 
From where i sit there's nothing more important to staying alive than keeping the fan turning and the flight controls working. ANY indication of a problem in either one of those systems demands immediate attention and corrective action.

"Root cause analysis" is great for desk jocks, but in my world keeping the fan spinning is way more important than your wallet. "Shotgun" trouble-shooting perhaps, but we need to get this problem resolved now before things go bad.

And if you decide to disect your old pump thats fine but you likely don't have the equipment to determine if was bad or not, and now the core value of that part is 0.
 
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FWIW, not long ago, I was chasing these same issues shown in the following link.
http://www.vansairforce.com/community/showthread.php?t=154433

It was driving me crazy. I replaced the mech fuel pump, flew for a while, replaced o-rings on the inlet/outlet of the pump, flew for a while, and so on.

Each time I would work on the pump, the first 1-2 hours of flight were perfect. Rock solid pressures. Then around flight hour 2-3, the fluctuations always reappeared back to around a 4 psi slow fluctuation. I quit worrying about it.

All this just to say, I really hope you have your problem fixed, but it may reappear in the next few hours of flight.
 
Fuel pump erratic behavior or pressure fluctuation does not have to be caused by a failing diaphragm,the check valves in the pump can cause this issue as well.
Also any small bit of debris in a check valve. Just a thought.

Keith
 
From where i sit there's nothing more important to staying alive than keeping the fan turning and the flight controls working. ANY indication of a problem in either one of those systems demands immediate attention and corrective action.

"Root cause analysis" is great for desk jocks, but in my world keeping the fan spinning is way more important than your wallet. "Shotgun" trouble-shooting perhaps, but we need to get this problem resolved now before things go bad.

And if you decide to disect your old pump thats fine but you likely don't have the equipment to determine if was bad or not, and now the core value of that part is 0.

I thought we had electric boost pumps specifically for issues like this?
 
This was posted in another fuel pressure thread. One was posted by another guy that I cut and pasted and the next post was by me. I personally believe this is what happens to my plane, but check everything because yours could be the same, or different. Ed

While I was building my 10 Scott S told me about the breather vent line possibly getting fuel in it when the tanks are full while climbing. I tried my best to install the line as close to the top of the tanks as I could. My fuel pressure will drop way down to 5 psi if I top the tanks completely and stay on a long climb. Of course I'll turn on the pump but I've seen 5 psi before I do. The engine has never stumbled during this phase. If I don't fill the tanks all the way it will not happen. Sometimes it doesn't happen with full tanks, just when I am doing long climbs with topped off tanks?? Just another reference


Just want to go on record that my RV-8 built in 2002 with an 400 hour since new IO-360 also sees these fuel pressure fluctuations. I always top my tanks when I fill up and it seems to be directly related to full fuel tanks in my case. Does not seem to be an issue after they burn down a bit. I hate it and wish it was not there but it is. Turning on fuel pump brings the pressure right back. Engine has never stumbled but I turn on the fuel pump as soon as the alarm goes off. Have seen it less than 7 pounds. Ed
 
Fuel pressure went from 25psi to 45psi

Hi Guys

I have been reading this thread with interest as I also have a fuel pressure issue.

My engine is a Lycoming IO-360M1B with 800 hrs since new.

Last weekend while flying home from a trip away my fuel pressure went from its normal 25psi to 45psi and stayed there.

CHTs were all approx 320F and EGTs were approx 1440F, basically the the same as always, fuel flow remained unchanged at 33 liters per hour, oil pressure remained unchanged at 79 psi.

Turning on the electric fuel pump made no difference to the fuel pressure indication.

When I landed I checked the mechanical fuel pump overflow, no oil dribbling out, basically all as normal except for the high fuel pressure indication.

I have a Dynon Skyview with Kavlico fule and oil pressure sensors.

I am suspecting perhaps a bad sensor (but they are meant to be bullet proof) more likely a wiring / connection issue?

I have not yet had a chance to dump the data logs.

I also did not look at the fuel pressure after landing during taxi as I was dealing with a 15 knot cross wind and rotor that got all of my attention so will do that this weekend.

Can anyone share thoughts or ideas on what else to check?

Cheers
 
My engine is a Lycoming IO-360M1B with 800 hrs since new.
Last weekend while flying home from a trip away my fuel pressure went from its normal 25psi to 45psi and stayed there.

I had one shoot up to some crazy number like 80psi. It's the VDO sender.
 
Walt knows

Hey Eddie, did you get that bulletproof idea from the movies? Just kidding, but I have yet to see any mechanical part on my RV that still looks and works the same after I shoot it. (So I stopped using the plane for target practice.) But, strangely enough.... things still need replacing. If I had to take sides.... and that is perilous on a forum.... I would agree with Walt.
 
I thought we had electric boost pumps specifically for issues like this?

Would you use that same philosophy if one of your ignitions was causing problems? (I doubt it)

You only have one path for fuel to get to that motor, best to keep it working correctly.

What good is engine monitoring if all you do in monitor the problem :rolleyes:
 
Would you use that same philosophy if one of your ignitions was causing problems? (I doubt it)

You only have one path for fuel to get to that motor, best to keep it working correctly.

What good is engine monitoring if all you do in monitor the problem :rolleyes:

So because I have an anomaly that occurs on an extremely intermittent basis, I should just start replacing parts? Or should one perhaps take some time to evaluate the data, understand the issue, and fix what's actually broken?

Part of the point of having a monitoring system is to monitor things and make *better* decisions about whether or what to repair or replace.

I could easily turn your statement on its head...why monitor something if you're just going to replace it at the first hint of anything unusual? Notice a slight roughness in flight? Don't bother downloading and analyzing the data, just pull both mags and send them in for overhaul right away! Fuel pressure drops out once in a great while? GOTTA be the fuel pump...replace it! Couldn't *possibly* be a cracked flare on a line, a loose fitting, a too-tight bend causing cavitation, a blocked filter or fuel pick-up, bad hose routings leading to heat-soaking/vapor lock, or any of a dozen other things. FUEL PUMP!

Look, maybe that was the problem here...if the replacement *appears* to fix the problem, cool. And we'll never know if the old one was bad unless the OP opens it up and looks, which seems unlikely.

If it didn't fix it, we'll know soon enough, and the only thing lost is his time and money.
 
I had one shoot up to some crazy number like 80psi. It's the VDO sender.

Hi Dan

I have the kavlico senders, but I guess what your saying is that its probably the sender ?

Is there anything else that could cause an increased pressure indication like I am seeing and yet everything else remains normal ?

Cheers
 
Hi Dan

I have the kavlico senders, but I guess what your saying is that its probably the sender ?

Is there anything else that could cause an increased pressure indication like I am seeing and yet everything else remains normal ?

Cheers

As much as I hate to say it, I have heard of fuel pumps failing this way. If you're lucky and you can duplicate the problem double check the pressure with another gauge (you can find cheap direct pressure gauges at most auto supply stores). The good news is the FI system will continue to work fine with 45 psi.

I also know Dynon has had some issues with pressure sensors/reading so verifying with another gauge would be prudent.
 
As much as I hate to say it, I have heard of fuel pumps failing this way. If you're lucky and you can duplicate the problem double check the pressure with another gauge (you can find cheap direct pressure gauges at most auto supply stores). The good news is the FI system will continue to work fine with 45 psi.

I also know Dynon has had some issues with pressure sensors/reading so verifying with another gauge would be prudent.

Thanks Walt I will be doing that this weekend.

Cheers
 
Would you use that same philosophy if one of your ignitions was causing problems? (I doubt it)

You only have one path for fuel to get to that motor, best to keep it working correctly.

What good is engine monitoring if all you do in monitor the problem :rolleyes:

AMEN!!!! I could NOT agree with you more regarding everything you have posted on this topic. The academia of some is all fine and good until someone looses an eye.

I am picking up the old pump today and will dissect it and see what I can find.

THANK YOU ALL for responding to this enlightening discussion.
 
Fuel pressure drops out once in a great while? GOTTA be the fuel pump...replace it! Couldn't *possibly* be a cracked flare on a line, a loose fitting, a too-tight bend causing cavitation, a blocked filter or fuel pick-up, bad hose routings leading to heat-soaking/vapor lock, or any of a dozen other things. FUEL PUMP!

Look, maybe that was the problem here...if the replacement *appears* to fix the problem, cool. And we'll never know if the old one was bad unless the OP opens it up and looks, which seems unlikely.

If it didn't fix it, we'll know soon enough, and the only thing lost is his time and money.

Wow....

Again, this was going on for months and gradually getting worse, going from something that was once every few flights to something that was happening twice every three hours. The airplane has 900h on it. I doubt the other laundry list of problems you listed (yes, we know...you're an AERONAUTICAL ENGINEER!!) could provoke this problem this late in the game.

To add to the absurdity of your argument, would you suggest that I remove the $300 pump and dissect it myself? Would I feel comfortable if I saw nothing wrong with it on the inside? Would I trust myself to reassemble it and reinstall it properly? Is it worth $300 to have the airplane down for a month while I send the pump out for overhaul by the manufacturer? Bench test (really????)? The answer to all of these is a resounding NO in my book.

Walt's advice (ALL of it) is spot on.

To this vascular surgeon (a field that deals very much with flow dynamics and pump failures), this was a pretty obvious problem and one that is neither uncommon nor insignificant. Too many accidents are caused by deliberate denial of symptoms for purposes of observation that were harbingers for catastrophic failures. To liken it to my profession; "That chest pain is probably indigestion. Your tests are normal so take some Tums and lets see how you feel in a week."

And in light of your rather negative insinuation that somehow I am lazy or don't care, I will fetch the pump and dissect it for you today with pictures to follow.
 
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Wow....

Again, this was going on for months and gradually getting worse, going from something that was once every few flights to something that was happening twice every three hours. The airplane has 900h on it. I doubt the other laundry list of problems you listed (yes, we know...you're an AERONAUTICAL ENGINEER!!) could provoke this problem this late in the game.

To add to the absurdity of your argument, would you suggest that I remove the $300 pump and dissect it myself? Would I feel comfortable if I saw nothing wrong with it on the inside? Would I trust myself to reassemble it and reinstall it properly? Is it worth $300 to have the airplane down for a month while I send the pump out for overhaul by the manufacturer? Bench test (really????)? The answer to all of these is a resounding NO in my book.

Walt's advice (ALL of it) is spot on.

To this vascular surgeon (a field that deals very much with flow dynamics and pump failures), this was a pretty obvious problem and one that is neither uncommon nor insignificant. Too many accidents are caused by deliberate denial of symptoms for purposes of observation that were harbingers for catastrophic failures. To liken it to my profession; "That chest pain is probably indigestion. Your tests are normal so take some Tums and lets see how you feel in a week."

And in light of your rather negative insinuation that somehow I am lazy or don't care, I will fetch the pump and dissect it for you today with pictures to follow.

Jesus, calm down. I frankly don't care what you do or how you solve your problem, I was only trying to say to make sure you're solving it and not hiding the real problem. It's no skin off my nose if you work the issue in any way you want to. I wasn't calling you lazy, either.

Wow. Forgive me all to h*ll for suggesting a methodical approach. Won't happen again.
 
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