RedRotors

I have some problem with the truck, the truck was idleling and then died.. After a while of cranking, still nothing.. Fuel filter is full, I unscrew the banjo bolt at the input of the pump, and the fuel spill when I crank the engine, so there's fuel at the input of the pump.. The cut-off solenoid seems to operate. I also unscrew one hard fuel line at the pump, going to the injector, no fuel, nothing at all while cranking the engine.. So im a bit mystified..

I unscrewed the overflow valve and while cranking, there's no fuel spilling, is it normal ?

Anyone has an idea?

Thanks,
Marc/

RedRotors

anyone?

Red.

John Faughn

When you mention pump , it would help to say which one , lift pump , main pump , just because the filter is full ,does not mean it isn't plugged .
I'm leaning towards a lift pump , fuel line or hose to tank .
Make some thing up to put & hold about 2-3 lbs pressure in tank , then look for leaks , top of tank , lines & hoses to lift pump [ this is vacuum under running conditions so no fuel leak ] with pressure & at least 1/4 tank , if there is a leak , now you will see fuel leaking .
Also check for fuel pressure by putting fittings together at filter housing or inlet to main pump for gauge , the over flow valve restricts return to tank , thus making fuel pressure from lift pump .

RedRotors

Hi John,

Sorry for the confusion, all the 'pump' in my message was the P7100.. Fuel filter is new, as well as the prefilter in the fuel heater. THe sender unit in the tank has been cleaned too.

So it's normal that i don't see fuel spilling out p7100 when i unscrew the overflow valve and crank the engine?

Thanks,
Marc/

TIMMY22

Try pumping the bulb on the lift pump 50 times or so.

Is this a result of a filter change?

John Faughn

There should be fuel , but no pressure to speak of , because you took out the device that makes pressure -OFV , take a 2nd look at my last post , start at tank , work your way up stream , I suspect the lift pump , but test everything so that you only replace what is needed .

RedRotors

I ripped off my thumb with pumping.. with no luck. Filter has been changed weeks ago.. The problem began before the fuel filter change.. The truck stopped a few times and I restart it and everything went ok.. that why i replaced the filter, but it did't cure the problem.. and i need the truck to work..

Cheers,
Marc/

RedRotors

Im gonna follow your advice.. starting by the tank.. Do you think that OFV might also be in cause?

thanks for your help.

Marc/

John Faughn

I found that the OFV & lift pump can have about the same life .
Last time I looked at this issue , the 1st symptom , was longer starts with a low tank or on a hill , my 1st thought was the system may be losing prime [ fuel lines or hoses ] I made a fixture with old fuel cap & pressurized the tanks with about 3 lbs - no leaks , I ended up taking the LP out & apart , because I was familiar with some of the internal parts , I could see the the check valves were in bad shape [ could not find replacements ] so put in
new LP , then did a pressure test , it was low , so then put in a OFV .
All is good now .
My best source for those is
Precision Diesel injection & turbo inc
Marty Tompkins 888-734-7346
Michigan , not sure about price but it used to be around $150 for both including sh.

RedRotors

Hey,

Sorry to bring back an old post.. but it finally ended up with a failed liftpump.. I put a new pump and the truck is running perfectly..

Thanks for the inputs..

Marc/