Engine Fuel Pump Failure

[DanH]

Originally Posted by eddieseve

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.

[flightlogic]

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.

[Walt]

Originally Posted by RV7A Flyer

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

[RV7A Flyer]

Originally Posted by Walt

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

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.

[eddieseve]

Originally Posted by DanH

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

[Walt]

Originally Posted by eddieseve

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.

[eddieseve]

Originally Posted by Walt

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

[jonweisw]

Originally Posted by Walt

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

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.

[jonweisw]

Originally Posted by RV7A Flyer

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.

[RV7A Flyer]

Originally Posted by jonweisw

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.