losing it prime
 

lately my truck has been losing it prime after only sitting for like 1/2 hr. cant seem to find where its coming from. anyone know where i should start or hear of anyone having probablems. say it will crank and crank but wont start. but if i bump the starter and let my raptor 150 run say i do that 2 or 3 times and it fires right up and runs fine.

Changing the overflow valve wouldn't hurt. They aren't very expensive, and can cause a lot of issues.

The return line banjo bolt on the back of the head is another common spot. Fuel won't leak out, but it will let air back in if it is loose.

i have used shop air in the tank to find leaks. be careful and not get too much. :hellox:

are the injectors kindal ike ford ones were they can leak down????

cummins is fuel pressure only

i still can find the probablem:argh: i still hv to cycle the lift pump even after sitting for an 1hr it will lose its prime. more input please:s:

did you pressure the tank up a little. :hellox:

What have you done so far so we don't repeat something?

Are you running the stock sending unit ? Rust was a problem with mine :c:

checked the overflow valve put a wrench on my fittings all seem tight. changes fuel filter with ne o-ring. have not put and pressure to it yet. and im sure its still the stock sending unit. all i did was put a raptor 150 on it. i notice soon as u turn the truck off the fuel press drops right off but shouldnt it have some even with the lift pump not running? if i cant find anything could i just run my raptor 150 hot all the time not one when u go to start the truck.

Below is how you test the Overflow Valve....

if its bad how would that make me lose my prime

If the overflow is stuck open even just a little it will allow the fuel in the vp to drain into the fuel return line and back to the tank. Does it loose prime even with a full tank of fuel?

well i hope everyone enjoyed there new years party. hope this year is better then the last. but anyhow i replaced my overflow valve yesterday and it didnt do a thing. iv gon throuh and put a wrench on every line i could. so im at a lose any more thought wht it could be??

well replace my overflow valve and still noting:humm: say it wont start untill u cycle the lift pump a few times. im running 20-21psi for fule pressure. what should i run for a psi. ik when i get on it it drops to about 15-16. also when i cycle the lift pump my edge cs will only read like 18 then soon as it stops it will drop to 0 within seconds?? i would think i would hole some fuel psi hence the reason i think im loseing my prime. or is my VP44 going :argh:

I would replace the connector tube o-rings and retorque the lines. 5 of 10 vp trucks that complain of extended crank times from my experience will have a leaking connector tube. I start here because its hard to confirm and very cheap to repair lol The other 5 are vp/lift pump issues. Ive seen a few occasions where aftermarket systems were leaking and loosing prime, maybe one cracked tank module. Used to use air to check them but a smoke machine is much more effective in the lp or suction side. 21+ psi will also cause a hard start.
Also wondering why or how you confirmed a loss of prime?
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i just figured i was losseing prime bc after u cycle the lift pump a few times it will start. and are u saying i should bake the pressure off my raptor 150 to 18 or so psi. i guess i can replace the connector tub o rigs. shouldnt be to hard of a job if i get i puller??

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well did some more looking today and i found fuel on the bottom on my raptor 150? say there are allen head bolts and i couldnt tighten them anymore looks like a seal or something is bad there

Thats probably the issue lol

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