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.

 

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

 

cummins is fuel pressure only

 

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

 

did you pressure the tank up a little.

 

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

 

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.