if i let my truck sit for just 2o min it seems to lose its prime. ive put a wrench on all injectors, the return line, my injection pump, and my fass 150 pump. i also put hose clamps on the fass lines, i replaced both filters. the truck will start fine when it is parked down hill but with it on flat ground it cranks for about 15-20 seconds. im not sure if i have something clogging a line or the suction line. or if there is a check valve in my tank?? but tomarrow im gonna pull the bed and open the tank and see if i find something odd?? any ideas on how to clean the lines, clean the pump, OR should i put a check valve in my tank before the fass pump? i really need help here im tired of this truck doing this thanks...

 

Bump the starter and let the lift pump run until it stops. Then start it. If there is a leak in the fuel system and it is draining back, then it should start normally.

 

Codes? Mine did this and I kept checking the things you checked until it just died one day and wouldn't restart. 1 new VP44 later truck back on the road.

 

there are no codes. if i bump the starter a couple times it fires rite up. im thinking its a check valve in my sending unit thats in my tank what do u think?

 

check the overflow valve next to the fuel inlet on the vp. take it off and put 14psi of air to it. if it moves befor 14 psi its reurning the fuel back to the tank and not building pressure, of course before doing that check for codes and that your lift pump is pushing.

 

I would replace all the flexible fuel hoses, including those on top of the tank. They may look good, but if they are more than three years old you likely have microscopic pin holes that allow air to infiltrate and allow the fuel to return to the tank.

A loose fuel filter will also allow the system to drop its prime, same for the fuel heater. All it has to do is allow air into the system.

You will never see any wet hoses, wet filter drain, or wetness around the filter or heater when this happens. As the air leaks are so small that diesel will not pass through.

 

I could be way off base with this but my 06 would crank long enough to get alot of funny looks when it was new. I took it in under warranty and the dealer flashed the ecu and that took care of it. Just a Thought

 

Have you checked the Injector Cross Over Tube O-Rings? My truck had a hard start problem and it ended up being the o-ring on number 5 cylinder. Replaced them all at the same time and problem has been gone since.