Hello I am having a problem with my truck..

92 Ford F-250 7.3L

It has a random problem, it will die right after starting it. Within 10 sec... it will do it on a cold start and after driving it all day. Sometimes it will go for weeks without dying at all. Then it will do it every day. When it does die, I can crank till the batteries are dead and it will not start. I take the fuel filter off and every time it is almost empty. I can see no visible leaking from the frame mounted pump to the engine. I just replaced the hoses, caps and o-rings that run between the injectors. I replaced the o-ring on the fuel heater and put in a new schrader valve. Thought one of those would be the problem, guess not. Any ideas?

 

you need to take a look at your injector caps, orings, and return lines...they can and will drain back all of your fuel to the tanks if a pin hole(which may not leak diesel out but will let air in) exists. teh caps are plastic, can crack etc...i would check those first it sounds like an air intrusion issue.

 

The pump itself can bleed off fuel, since you say it will do it even after it has run all day I am more inclined to believe your transfer pump is the culprit.
It is also possible that you have a restriction between the tank and pump, but usually they will starve for fuel while running if this is the case.

 

Im trying to fix my own truck so i am no diesel guru believe me...BUT... i would go buy a fuel pressure tester and have it handy so when/if the next time this issue comes up you can test your fuel pump right at that moment.-----------i dont know if you have an electric pump but if you do during these times you might want to check connections.

Edit-find the post that is labeled "air in fuel-wits end"---just read it and hes having a very similar problem.

 

@ Ffemt10
I just replaced the injector caps, orings, and return lines, they are not leaking fuel and there are no visible cracks and or holes that i can see.

@ starmilt
I forgot to mention it has 2 tanks and the problem happens on both tanks. If it is the transfer pump, is this the pump located on the frame, driver side between the tanks and the engine? Or would this be the valve that switches between the tanks, it has lines from both tanks running to it. and is there a way to test the pump? Or since it does not happen all the time, do i just replace it and hope it is fixed?

 

when it dose this, pull the fuel filter and see if its full of fuel. if its anything but full clear to the top then your problem will be from that point back to the tanks. i would first be looking at the lift pump. the diaphram is probably starting to fail

 

Silent,

I am with Country boy, in that if it is happening on both tanks and you say that your filter is nearly empty when it does, it sounds like your lift pump is beginning to fail. Seems odd that it is random though. I would start there since this is a wear item anyway, so at least you can eliminate it as a cause.

Good luck,

Mac.

 

agreed^^^^^^

 

On the frame, that is the tank selector valve, I am thinking your mechanical pump may be the problem. You haven't been making motor oil have you.
The random problem could possibly be where the diaphram is at in your pump when you kill it.