What's new
Van's Air Force

Don't miss anything! Register now for full access to the definitive RV support community.

fuel pump failure within the first hours

KayS

Well Known Member
Hi All,

my 7 has now 35 hours on it and it seems my mechanical fuel pump (Tempest AF 15473) fails. the transparent nylon tube at the overflow outlet showed blue avgas-colour from the beginning. i wasn't aware that this is a problem until lately. i understand now there's only fuel at the overflow when the lower diaphragm leaks. well, the entire project took much longer than expected so the pump was sitting dry for ten years, maybe that caused the problem. i do have some questions...

1. i assume that this failure is very critical, although i have a electrical boost pump. would you ground the aircraft for now?
2. do i have to replace the whole thing or is there a solution by just to replace the diaphragms? i don't know if the diaphragms are supposed to be replaceable. el cheapo as i am it would be nice if that's possible.

at 20 hours my skyview went down the drain and now that. phase 1 doesn't run extremly smooth i would say. :eek:

any help is very appreciated.

Cheers
Kay
 
It depends on your confidence in your boost pump. Most are rated for continuous duty, but it's supposedly your backup and now you have no other backup. Personally, I wouldn't fly it electively on my boost pump alone.

I consider my engine-driven fuel pump to be the primary source of fuel pressure and I wouldn't fly the airplane if didn't generate sufficient fuel pressure all by itself. I was faced with this very issue as I was ferrying my new RV-9A back home. I grounded it at a small Iowa airport until I could get a new fuel pump shipped in.
 
Last edited:
the boost pump is from airflow performance and continous use. the question is against what the electric boost pump is pumping if the second diaphragm fails.
 
Fuel Pumps...

In my Comanche the mechanical fuel pump failed within a few hours of a fresh engine overhaul. Tempest fuel pumps seem to be doing everything they can do to ruin the idea that mechanical fuel pumps never fail.

They promised to replace that pump but still haven’t sent me one months later, by the way.

As for flying, if I broke away from home and needed to get her back I’d consider it (flying high and ready to glide her in somewhere)...once home she’d sit until mechanical is replaced.
 
Hi All,

my 7 has now 35 hours on it and it seems my mechanical fuel pump (Tempest AF 15473) fails. the transparent nylon tube at the overflow outlet showed blue avgas-colour from the beginning. i wasn't aware that this is a problem until lately. i understand now there's only fuel at the overflow when the lower diaphragm leaks. well, the entire project took much longer than expected so the pump was sitting dry for ten years, maybe that caused the problem. i do have some questions...

1. i assume that this failure is very critical, although i have a electrical boost pump. would you ground the aircraft for now?
2. do i have to replace the whole thing or is there a solution by just to replace the diaphragms? i don't know if the diaphragms are supposed to be replaceable. el cheapo as i am it would be nice if that's possible.

at 20 hours my skyview went down the drain and now that. phase 1 doesn't run extremly smooth i would say. :eek:

any help is very appreciated.

Cheers
Kay

1. Ground the plane until a new mechanical pump is installed. Very risky to fly it with a rupture in the fuel pump diaphram.
2. You will not be able to repair the pump. Buy a new one.
3. 10 years is the manufacturer’s recommended life span, whether flown or not, based on rubber deterioration. Your time is up.
 
Please read up carefully on how to replace the fuel pump. It is a little bit tricky because the plunger rod that actuates it off the cam comes down from the top, and gravity makes it not want to stay up out of the way while you snake the fuel pump into position.

It is actually possible to force the pump into position with the plunger down, and alongside the actuating arm on the pump. An unfortunate soul did this near Grass Valley-Nevada City about 10 years ago. He was also in phase I with about 30 or so hours. It ended really badly.

There are a couple of tricks to help this. You must turn the engine over to the point where the plunger is fully up out of the way when pushed up against the cam. Then you have a couple of choices.
If you remove the left magneto, it is possible to reach in and hold the plunger up, AND see that it is in the correct position. Or, if you absolutely do not want to take that mag out for some reason, you can put a loop of fine safety wire or string around the plunger and out to some convenient point to tie it off. (don't make a lasso loop, just in, around the plunger, and out.) The tension in the wire puts enough side load and friction on the plunger to keep it from falling down, so you can snake the pump into position. Then, when the pump is drawn up to about 1/8" from final seated position, you pull the wire out.

The way the bolts are located in the fuel pump, it is not possible to put the pump all the way into position and then install the bolts. You have to get the pump in about the right spot, start the bolts, then push the pump in a bit more, tighten the bolts more, push the pump in some more, tighten the bolts some more, etc. until it is all the way in. Don't forget to stop at some point to pull your wire loop out.

Good luck.

Oh, you might want to consider whether you want to install a cooling shroud around the pump while you are at it. Many do. Many don't.
 
Last edited:
Then you have a couple of choices.
If you remove the left magneto, it is possible to reach in and hold the plunger up, AND see that it is in the correct position. Or, if you absolutely do not want to take that mag out for some reason, you can put a loop of fine safety wire or...

Even if you're not comfortable pulling a mag, the first option is the easiest. Get a buddy or local A&P to help. You'll <probably> substantially reduce the time and frustration involved.
 
Thanks for all your valuable responses! I love VAF. Will try to organize a new pump tomorrow and see how much PITA the replacement is.

Btw: i have the cooling shroud already. I hate the idea to remove the PMAG, one of the items that actually work and shouldn't be touched.
 
Please read up carefully on how to replace the fuel pump. It is a little bit tricky because the plunger rod that actuates it off the cam comes down from the top, and gravity makes it not want to stay up out of the way while you snake the fuel pump into position.

It is actually possible to force the pump into position with the plunger down, and alongside the actuating arm on the pump. An unfortunate soul did this near Grass Valley-Nevada City about 10 years ago. He was also in phase I with about 30 or so hours. It ended really badly.

There are a couple of tricks to help this. You must turn the engine over to the point where the plunger is fully up out of the way when pushed up against the cam. Then you have a couple of choices.
If you remove the left magneto, it is possible to reach in and hold the plunger up, AND see that it is in the correct position. Or, if you absolutely do not want to take that mag out for some reason, you can put a loop of fine safety wire or string around the plunger and out to some convenient point to tie it off. (don't make a lasso loop, just in, around the plunger, and out.) The tension in the wire puts enough side load and friction on the plunger to keep it from falling down, so you can snake the pump into position. Then, when the pump is drawn up to about 1/8" from final seated position, you pull the wire out.

The way the bolts are located in the fuel pump, it is not possible to put the pump all the way into position and then install the bolts. You have to get the pump in about the right spot, start the bolts, then push the pump in a bit more, tighten the bolts more, push the pump in some more, tighten the bolts some more, etc. until it is all the way in. Don't forget to stop at some point to pull your wire loop out.

Good luck.

Oh, you might want to consider whether you want to install a cooling shroud around the pump while you are at it. Many do. Many don't.

I observed this Lycoming engine-driven pump replacement problem first-hand at a little airport in Iowa. The A&P worked for hours trying to manage the plunger after the sticky-grease method failed. When he hit upon using the safety wire to hold the lever down, replacing that fuel pump became a 30 minute exercise.


...
 
Last edited:
Please read up carefully on how to replace the fuel pump. It is a little bit tricky because the plunger rod that actuates it off the cam comes down from the top, and gravity makes it not want to stay up out of the way while you snake the fuel pump into position.

It is actually possible to force the pump into position with the plunger down, and alongside the actuating arm on the pump. An unfortunate soul did this near Grass Valley-Nevada City about 10 years ago. He was also in phase I with about 30 or so hours. It ended really badly.

There are a couple of tricks to help this. You must turn the engine over to the point where the plunger is fully up out of the way when pushed up against the cam. Then you have a couple of choices.
If you remove the left magneto, it is possible to reach in and hold the plunger up, AND see that it is in the correct position. Or, if you absolutely do not want to take that mag out for some reason, you can put a loop of fine safety wire or string around the plunger and out to some convenient point to tie it off. (don't make a lasso loop, just in, around the plunger, and out.) The tension in the wire puts enough side load and friction on the plunger to keep it from falling down, so you can snake the pump into position. Then, when the pump is drawn up to about 1/8" from final seated position, you pull the wire out.

The way the bolts are located in the fuel pump, it is not possible to put the pump all the way into position and then install the bolts. You have to get the pump in about the right spot, start the bolts, then push the pump in a bit more, tighten the bolts more, push the pump in some more, tighten the bolts some more, etc. until it is all the way in. Don't forget to stop at some point to pull your wire loop out.

Good luck.

Oh, you might want to consider whether you want to install a cooling shroud around the pump while you are at it. Many do. Many don't.

Some great tricks, will use these next time...

A word of caution on the plunger...I’ve seen one fall completely out and down into oil pan on an O-540. A magic man of a A&P I know was able to fish it out and replace it back up into its proper position with a magnet...I guess what I’m saying is be gentle manipulating that plunger inside that recess.

I replaced my pump on my RV-4 without pulling a mag without too much trouble. My biggest issue was getting the bolts into place...who ever designed the bolt head/clearance on these fuel pumps needs be hung by their toenails.
 
I replaced my pump on my RV-4 without pulling a mag without too much trouble. My biggest issue was getting the bolts into place...who ever designed the bolt head/clearance on these fuel pumps needs be hung by their toenails.

On mine, I noted that the prop governor created a serious impediment to managing the bolts.
 
Some great tricks, will use these next time...

A word of caution on the plunger...I’ve seen one fall completely out and down into oil pan on an O-540. A magic man of a A&P I know was able to fish it out and replace it back up into its proper position with a magnet...I guess what I’m saying is be gentle manipulating that plunger inside that recess.

I dont have a 540 manual handy to check if it is different, but on a 360, the plunger has a flange on the top that is pushed on by the gear cam, and that flange will stop the plunger from falling down and out - so in the case you’re talking about, the plunger was installed upside down!

Paul
 
I replaced one in the transient parking near Buffalo NY several years ago. Went in easy. Again a year later in our hangar. No issues. Something that really helped was to grind down the shaft of the 5/16” Allen wrench so it clears the pump housing, so you can get the bolts started straight. Use a cheater open end wrench to get leverage. Did not use any of the tricks listed above other than making sure the plunger is in the highest position before starting.

Must have just been lucky. After reading all these stories about installing, I realize that. Didn’t know any better at the time.
 
short update: i am still in the middle of the process and have an very hard time to keep the rod in the upper position.

Whoever designed that system should be sentenced to five years in a maximum security maintainance shop, replacing his fuel pump all day long!!!

end of rant.
 
short update: i am still in the middle of the process and have an very hard time to keep the rod in the upper position.

Whoever designed that system should be sentenced to five years in a maximum security maintainance shop, replacing his fuel pump all day long!!!

end of rant.

Pull the left mag and it gets much easier because you can reach in through that hole with one hand and hold the rod in place while you attach the pump with your 3 other hands.
 
I understand now there's only fuel at the overflow when the lower diaphragm leaks.

Leak at the pumping diaphragm (the one just below the vent ring) or the base plate diaphragm. There is a vent passage from the base to the vent ring space. Just polishing the pins....

well, the entire project took much longer than expected so the pump was sitting dry for ten years, maybe that caused the problem.

I tore down a 10 year old Lycoming pump and found badly deteriorating rubber. Never exposed to anything but avgas, so it had to be age.

do i have to replace the whole thing or is there a solution by just to replace the diaphragms?

Can't replace them. Buy a new pump.

BTW, I installed a Tempest pump, which is doing fine so far. Check back in six years or so.

Lycoming pump photos:
 

Attachments

  • Damaged Fuel Diaphragm1.jpg
    Damaged Fuel Diaphragm1.jpg
    82.8 KB · Views: 161
  • Damaged Fuel Diaphragm4.jpg
    Damaged Fuel Diaphragm4.jpg
    90.4 KB · Views: 138
Get used to pulling the Pmag and reinstalling. I was like u back in the “early” days of my RV. But after several 100 hour checks and replacing an ignition coil, this is now routine and very EZ. I’ve had no fuel pump problems but when I do pulling the Pmag will be my first step.
 
I gave up for now. today's battle is lost but the war is not over yet. I hate the idea to pull the PMAG but will consider that if everything else fails.

But i wonder... if you put the pump in, the pump's actuator arm touches the cam rod. You can really feel the rod and push it upwards with the pump's arm. It's cold today and there's some resistance when the rod is pushed up. The rod also doesn't fall down, it slides down gently. I tried to put in the pump, with the arm alongside the rod but it seems that this is basically impossible without tilting the pump. So i am close to just try it by feel.

Kinda hard to explain in a foreign language.
 
One trick I have used to slow the “fall” of the pushrod (once you have pushed it up) is a small blob of thick white lithium grease to act as a temporary adhesive. You put it on the bottom of the rod, through the pump lever hole. This is if you’re not using the lasso technique. Once the engine is turned, the blob goes away and will dissolve..

Paul
 
This is if you’re not using the lasso technique.

+1 for the lasso trick, which Steve described in post 6. Drape the free end of the string over a motor mount tube and hang something heavy on it.
-
 

Attachments

  • Pump Plunger.jpg
    Pump Plunger.jpg
    12.9 KB · Views: 267
One trick I have used to slow the “fall” of the pushrod (once you have pushed it up) is a small blob of thick white lithium grease to act as a temporary adhesive. You put it on the bottom of the rod, through the pump lever hole. This is if you’re not using the lasso technique. Once the engine is turned, the blob goes away and will dissolve..

Paul

I’ve used this same technique with success
 
tried the lasso trick but after three hours or so i realized that it doesn't work for me.

I have a tube of sticky fuel lube (EZ turn). Would a good amount of that stuff do any harm to the oil system?
 
Last edited:
One important lesson I learned doing mechanical work is most times it takes longer to do the job taking "shortcuts", than if I had just taken the time to do it the harder way. Short cuts are fine for the experienced expert, but mess this job up and you could be looking at some serious engine damage.
 
Don't use EZ turn.

Try again with string..... nice thick string like kite string. The thick string gives enough friction to hold up the rod. Tie one end off on top of the motor and the other to a bungie so it will apply pressure and hold the rod in place. The thicker string provides more friction. Confirm that indeed the string is holding up the rod.

Make sure the prop is positioned so the rod is in full up position. Turn the prop and push the rod up with your finger (or someone's longer finger.)

I used Permatex #2 on both sides of the gasket and on the threads (none on the first two threads) of the bolts. The bolt holes pass all the way through and can leak oil.

Install the pump with the right bolt in the right pump hole. The pump should go in within a 1/2 inch or less of contact. Pull it back just enough to get the right bolt started. You might need to twist the pump a little as it is canted clockwise a little.

With the bolts started, push on the fuel pump, you should feel it spring back. Remove the string and tighten the bolts with a T allan wrench.

The only thing I would do different next time is cross drill the bolt heads so you have more options to thread the safety wire.......THAT was areal P.I.T.A.
 
Last edited:
Try dental floss instead of string. The flat kind should work good, and it's STRONG! Don't use EZ turn.

-Marc
 
Try dental floss instead of string. The flat kind should work good, and it's STRONG! Don't use EZ turn.

-Marc

^^^ Having done fuel pump replacements too many times, flat floss works great - will never do it any other way.
 
^^^ Having done fuel pump replacements too many times, flat floss works great - will never do it any other way.

Thin safety wire works well too.

For what it is worth, I never had success using something "sticky" like grease or fuel lube to hold the rod.
 
update: tried the string method again and this time it worked. pump is installed now. next thing is to safety wire the bolts and to reconnect everything. i have no idea how to put safety wire to the bolt heads but we'll see.

have to admit that i really hate that pump. it's a bad design in my very personal opinion.

thanks again for all the great help.
 
pump is replaced and does it's job. I can't send the old pump as a core so now it's just a paperweight. What could we do with the old pump?
 
Disassemble it and present the photos here on VAF so that everyone can understand what's inside these things.

First, though, do a search - I bet Dan H already did that.

Dave
 
Folks,

imagine you have all this hassle in replacing your machanical fuel pump. you need four days of blood, sweat and tears to put in the new one and than bad weather covers half of europe for three weeks.

then you make a ground test and your Dynon shows only 6 - 7 PSI fuel pressure instead of the 25 PSI or so required for your injected lycoming. if you apply power without the boost pump the engine feels like it's having vapor lock. turning on the boost pump and everything is fine.

then you figure out that tempest builds two versions of the fuel pump. one with low pressure for carburator and a high pressure version for injected.

and guess which one i installed... yikes.
 
Ouch!

Folks,

imagine you have all this hassle in replacing your machanical fuel pump. you need four days of blood, sweat and tears to put in the new one and than bad weather covers half of europe for three weeks.

then you make a ground test and your Dynon shows only 6 - 7 PSI fuel pressure instead of the 25 PSI or so required for your injected lycoming. if you apply power without the boost pump the engine feels like it's having vapor lock. turning on the boost pump and everything is fine.

then you figure out that tempest builds two versions of the fuel pump. one with low pressure for carburator and a high pressure version for injected.

and guess which one i installed... yikes.
Very frustrating, I'm sure! Hang in there - you'll get it flying again soon!
 
While we’re talking fuel pumps here, I just replaced my mechanical fuel pump on my carberated O-320 last week. The replacement went well and the engine runs normally but I am seeing significant fluctuations in its pressure output from as low as 2.9 psi to as high as 8.1 psi. Does this seem normal?
 
Folks,

imagine you have all this hassle in replacing your machanical fuel pump. you need four days of blood, sweat and tears to put in the new one and than bad weather covers half of europe for three weeks.

then you make a ground test and your Dynon shows only 6 - 7 PSI fuel pressure instead of the 25 PSI or so required for your injected lycoming. if you apply power without the boost pump the engine feels like it's having vapor lock. turning on the boost pump and everything is fine.

then you figure out that tempest builds two versions of the fuel pump. one with low pressure for carburator and a high pressure version for injected.

and guess which one i installed... yikes.

When my engine-driven fuel pump went out, it was at a tiny little rural Iowa airport on a Sunday afternoon on the last leg of a 500 mile flight and about 200 miles from home. I couldn't believe my luck that the A&P, who was nice enough to come in from home on a Sunday, said that he had one he'd just taken off a Lycoming he was re-building. After struggling with the plunger problem for a couple of hours, he got it in, but starting it up showed low fuel pressure because...you guessed it...it was the pump for the non-injected Lycomings...(4-6 psi). I ended up with that 40296 Tempest pump (25-30 psi) which has been working just fine.
 
When my engine-driven fuel pump went out, it was at a tiny little rural Iowa airport on a Sunday afternoon on the last leg of a 500 mile flight and about 200 miles from home. I couldn't believe my luck that the A&P, who was nice enough to come in from home on a Sunday, said that he had one he'd just taken off a Lycoming he was re-building. After struggling with the plunger problem for a couple of hours, he got it in, but starting it up showed low fuel pressure because...you guessed it...it was the pump for the non-injected Lycomings...(4-6 psi). I ended up with that 40296 Tempest pump (25-30 psi) which has been working just fine.

Sounds like a nice guy, but as an AP he should have known better.
 
Sounds like a nice guy, but as an AP he should have known better.

Yup, I agree. But he didn't charge me for that Sunday afternoon labor, only for the new pump, and for the work of removing the old one and installing the new one. So that aspect of the adventure didn't cost me anything, and the plane wasn't going anywhere anyway so it didn't cost me any time either. He did charge me $15/day to borrow his car to drive the rest of the way home.
 
i once replaced my electric aux. pump with what i thought was an identical pump. when i turned this electric pump off after the engine start the silence was deafening. i had gotten a slightly different model pump with a check valve. my pumps were in series. i would have been a busy boy trying to figure that one out if i had forgotten it and not shut it off until after takeoff.
 
While we’re talking fuel pumps here, I just replaced my mechanical fuel pump on my carberated O-320 last week. The replacement went well and the engine runs normally but I am seeing significant fluctuations in its pressure output from as low as 2.9 psi to as high as 8.1 psi. Does this seem normal?

This is unfortunately pretty normal with our carbed planes - many threads about low or erratic pressure indications, but in the end, the engines keep running and people live i with it. It seems to be a combination of what transducer/EFIS/EMS/gauge you are using and how you have the transducer mounted.

The unfortunate part about it is that sometimes, the fuel pressure might REALLY be indicating a problem, but we are so used to bad indications that it gets ignored....

Paul
 
This is unfortunately pretty normal with our carbed planes - many threads about low or erratic pressure indications, but in the end, the engines keep running and people live i with it. It seems to be a combination of what transducer/EFIS/EMS/gauge you are using and how you have the transducer mounted.

The unfortunate part about it is that sometimes, the fuel pressure might REALLY be indicating a problem, but we are so used to bad indications that it gets ignored....

Paul

Guilty. I stopped messing with errant (carb) fuel pressure indications long ago. Maybe I'll get back to working on that some day.
 
No question in my mind. I agree 100% with Bob Barrow.

Ground the airplane
Replace the pump

Having done this job, I also advise pulling the left mag to hold up the plunger while the new pump is installed. Seems to me I recall a magazine article on this in maybe Kitplanes or sport aviation. Safety wiring the bolts can be a bit difficult depending on hoses, etc. Hoses, engine controls, etc. can be removed and reinstalled as well to make the job easier. If you somehow improperly jam the pump arm in without the floating shaft in position above it, you will have a much bigger problem than you do now.

Ellis
A&P/IA
 
Last edited:
update: installed the (hopefully) correct pump today. Several weeks ago i needed around 20 hours to replace the original pump with the wrong low pressure version. today it took just 5 hours to put in the high pressure pump.

Amazing how much faster we are if we do a something again.
 
i once replaced my electric aux. pump with what i thought was an identical pump. when i turned this electric pump off after the engine start the silence was deafening. i had gotten a slightly different model pump with a check valve. my pumps were in series. i would have been a busy boy trying to figure that one out if i had forgotten it and not shut it off until after takeoff.

Happened to a friend of mine. He never checked it on the ground for some reason prior to first flight. Took it up and when he turned off the pump the engine quit. He had the wrong pump. Why he never checked on run up I’ll never know. He got away with it.
 
In my case the injected lycoming was running "ok" with the low pressure mechanical fuel pump and the electric boost pump off. Applying higher throttle and it started to stumble a bit. It was running near the edge and hard to figure out at the run up mag check which i do with 1600 RPM or so.
 
My fuel pump overflow started leaking so I just bought a new Lycoming fuel pump to install. IO-360. I can't move the actuator arm by hand. Is this normal? How much pressure is required to move the arm?
 
My fuel pump overflow started leaking so I just bought a new Lycoming fuel pump to install. IO-360. I can't move the actuator arm by hand. Is this normal? How much pressure is required to move the arm?

A lot. Can’t really actuate the lever by hand.
 
" word of caution on the plunger...I’ve seen one fall completely out and down into oil pan on an O-540. A magic man of a A&P I know was able to fish it out and replace it back up into its proper position with a magnet...I guess what I’m saying is be gentle manipulating that plunger inside that recess."

The plunger cannot fall out if it is installed Correctly! The button on the plunder that would prevent it from being able to slide out of it's passage goes toward the cam that drives it. The plain end goes toward the pump. The engine you observed has the plunger in upside down unless you were working on the engine inverted. :rolleyes:
Good Luck,
Mahlon
 
After my high pressure mechanical fuel pump failed recently, and reading the horror stories about replacing it, I thought I was well prepared for the task. Ordered a new Tempest pump, removed the old one after disconnecting all the lines that impeded access, and attempted to fit the new one. I tried cleaning the pushrod and applying thick grease to no avail, then tried the dental floss trick and tied the floss around the pushrod and up to the top of the engine mount, using a zip tie to firmly tension it. This time, the pump slid home nicely instead of getting cocked to one side. Success, or at least I thought. Firing up the engine revealed no fuel pressure, only this time I removed the left P-Mag and sure enough, I could see the push rod was not in contact with its cam, so pulled the pump again, but only to nearly the end of the threads of the retaining bolts. I could easily lift the pushrod up away from the pump arm using a narrow strip of aluminium, whilst seating the pump back on the accessory case, then tightening the bolts. Even safety wiring them was fairly painless this time around. So for me it is a no brainer. Remove the left mag, then there is no question over whether the job has been done right.
 
I would worry now that maybe the fuel pump lever may be bent, or the plunger is bent. Is there enough "give" in the fuel pump lever to flex to the side as the pump is screwed down and moves to center?
After my high pressure mechanical fuel pump failed recently, and reading the horror stories about replacing it, I thought I was well prepared for the task. Ordered a new Tempest pump, removed the old one after disconnecting all the lines that impeded access, and attempted to fit the new one. I tried cleaning the pushrod and applying thick grease to no avail, then tried the dental floss trick and tied the floss around the pushrod and up to the top of the engine mount, using a zip tie to firmly tension it. This time, the pump slid home nicely instead of getting cocked to one side. Success, or at least I thought. Firing up the engine revealed no fuel pressure, only this time I removed the left P-Mag and sure enough, I could see the push rod was not in contact with its cam, so pulled the pump again, but only to nearly the end of the threads of the retaining bolts. I could easily lift the pushrod up away from the pump arm using a narrow strip of aluminium, whilst seating the pump back on the accessory case, then tightening the bolts. Even safety wiring them was fairly painless this time around. So for me it is a no brainer. Remove the left mag, then there is no question over whether the job has been done right.
 
I had to replace my LW-15472 fuel pump due to variable fuel pressure.... going down to zero PSI. Fuel flow was not an issue. I already checked the plumbing and replaced the pressure sensor. Never a problem with the electric pump on.

I am glad I found the issues, difficulties and tricks in this thread. I did the job within 4.5 hours including cowl off, on, ground test and log book entry.

Challenges/ solutions:
1. Access : I removed the left mag and I already replaced the governor pad with a simple plate (my plane is fixed pitched)
2. The infamous dropping pin: with left mag removed, it is very easy to hold it in place and double check that all is ok. Took 5 min to put the pump in place.
3. Safety wiring (especially the right bolt): I drilled additional holes to insert safety wire from any angle (3 pairs of holes). Took 10 min to safety wire.
4. Hex nut access and difficult to screw: I bought a long 5/16 hex tool with 3/8 drive. No issue. I could easily use the torque wrench.

Steps were:
. Remove cowling
. Remove top spark plugs
. Remove left mag
. Remove fuel pump
. Examine how all is made; some camera shots (step not needed)
. Transferred the fittings on new pump
. Installed new pump
. Installed left mag
. Timed left mag
. Installed spark plugs
. Ground test
. Inspection for leaks
. Reinstalled cowling
. Log book entry
 
Last edited:
Back
Top