What Would Make A Fuel Pump Fail?

[kevinmrowland]

Other than age, what is there that could casuse a mechanical fuel pump on an FJ60 to repeatedly fail?

My truck would not idle, I did all kinds of things to fix it, then replaced the fuel pump with another used one.
Immediately fixed the problem.
Ran GREAT for awhile then the same symptoms came back.
I figured, "no big deal" it was old and probably dried out.
Replaced it with a brandy new OEM pump.
Ran GREAT for awhile then the same symptoms came back.
Now I think there is something odd.

This is over several tanks of gas from different stations and 3 new fuel filters. Is there anything else that could be contributing to the failure?

Oh, and all of these fuel pumps check out just fine as per the FSM, whether new, used or not working. Is there a more technical test than "plug hole with finger......"????

Thanks,
Kevin R.

 

[Japan4X4]

Can't recall the year, not a real 60s guy, but some of them used a spacer between the pump and the block. No spacer and you soon bend the arm up till it won't work.

Any 60s people care to fill this in a bit?

 

[3_puppies]

As above are the arms still good,

shooting in the dark here. maybe not failing, maybe collapsing rubber fuel line? or other blockage, some PO put another fuel filter on it in a strnge location?
which would act like it is starving for fuel

 

[brian]

1/79-8/87 2F's have a spacer/insulator.
though sor "says" on the 7/79-10/84's "only some have it".

though it looks large enough, that if the pump is installed without one, when it needs one, the pump would'nt work at all.

it does sound like you have issues though. if you're burning up fuel pumps in the time it takes to a burn a tank of gas.

 

[kevinmrowland]

Sorry, I forgot to mention that the spacer is in place, that is usually the first thing that pops into my head when anybody mentions fuel pump problems.

Good idea about a cheap line collapsing but all the fuel lines on this truck are the nice reinforced OEM ones.
And there is definitely not any other hidden filters or unknown stuff (frame off rebuild)


This could just be a fluke, the first pump had over 300k miles on it. Perfectly reasonable for it to fail.
The second pump was used and had not been run in at least 5 years. So that could easily have a cracked diaphragm.
The third pump was new OEM, but it could have been the one in a thousand to have a defect.

It is just a little disconcerting that they all failed in such quick succession.

 

[brian]

used fuel pumps are always a crap shoot. i would'nt use one unless i was stuck some place and there was no other way.

the new oem is sorta alot disshearting.

i forget the exact number, but a pump should make something 8-10psi.

 

[3_puppies]

had another thought, could the return be blocked?

 

[kevinmrowland]

had another thought, could the return be blocked?

I can blow air back through it, that should be the only check, right?

I had the used pump from another truck as an emergency spare.

8-10 psi? can I just pick up any old fuel pressure gauge and put it in line with the output? Is that how that works? Or would I put a gauge on the output, not in line?

 

[brian]

just pull the line at the carb.
just a regular old gauge. most are fuel pressure and a vaccum gauge all in one. both handy to have.

and it's 3.5-4.75psi.

 

[kevinmrowland]

Cool. Was that in the FSM? I did not see those specs in the "fuel" section. I am beginning to learn that not all FSM's are created equal.
I have a vacuum/pressure gauge. I will figure out how to afix it to the fuel line.
Thanks for the info.

 

[GZERO]

didn't saw it mentioned on the thread, but how does the tank looks? also, how much are you revving the engine? since they usually fail at high rpm.

 

[kevinmrowland]

didn't saw it mentioned on the thread, but how does the tank looks? also, how much are you revving the engine? since they usually fail at high rpm.

How does the tank look in what regard? There does not seem to be any external damage, the filters are not clogged with rust or particles.

And I drive my cruiser like the tractor it is. I pretty much never go over 2500-RPM, I have a 5 speed so highway RPMS are low as well.

 

[roscoFJ73]

Kev you got a PM

 

[Dynosoar]

Flat spot on eccentric on the cam. I have seen it a few times with the kind of milage you are talking about (300k). The Factory cam is kind of a weak link it has a flash crome plate on it and is not hardened to todays specs.

my 2¢

Dynosoar

 

[kevinmrowland]

I'll check that when I pull this next one off. I have not looked at the actual lobe, but the pump arms have not been chewed up or irregular.
Thanks

 

[GZERO]

How does the tank look in what regard? There does not seem to be any external damage, the filters are not clogged with rust or particles.

And I drive my cruiser like the tractor it is. I pretty much never go over 2500-RPM, I have a 5 speed so highway RPMS are low as well.

what i meant is did you took a peek inside of it? sometimes they look good and all from the outside, but maybe in one point of its life got water inside and now is rusty, but if you say you're filters look good, then i don't think. But also, is not that hard to look inside just to make sure.

 

[kevinmrowland]

Well about 5 years ago I picked the cleanest tank from my stack, it was all clean and shiny at that time. Since then nothing would indicate that anything unwanted has entered the tank.

How do you suggest taking a peek inside the tank? I am usually the one who post up and says, "hey, thats easy"
The filer neck seem to be a no-go, it's got that bend in it and the unleaded choke down is to small to shine a light through. The only thing I can think of would be the fuel gauge access panel under the rear carpet.
Got any other idea? Since I have about 400lbs of stuff in the back that I would rather not have to move

 

[brian]

crawl underneath it with a 3" holesaw in drill......

 

[kevinmrowland]

Hole saw!?!?!


The torch would be way faster.

 

[brian]

Hole saw!?!?!


The torch would be way faster.

true, but the time you saved cutting it would be wasted when you try to weld it back in ;p