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Discussion Starter · #1 ·
so truck died at red light tonight after I just ran it real hard.. has barley any fuel pressure I bumped key to get lift pump to ran and it sound real funny and would only be at 5 pis or 2 psi when normally its at 18 psi idk if its fuel pump or maybe lift pump it could as be froze I guess it about 20 degrees out.. but ive been have problems with the truck if I run it hard when I let off it well idle rough like its lopeing but only for like 30 seconds the clears up still had normal power I thought I just had a injector sticking opening problem has only happened 4 times in last two months.. any suggestions on the fuel part truck wont start..
 

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Yep sounds like you air locked it.
 

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May sound dumb but have you checked your filters? I had something very similar a while back and my filters were almost new but a piece of something got caught and was restricting flow to my pump mostly at idle. If that doesn't help there is a small plastic check valve behind the tank return line on the FASS systems that can be prone to getting groves and not sealing right which will then not let pressure build correctly.
 

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definitely vapor locked it, bleed the fuel system by opening the injector lines and priming the pump. I believe they're 3/4"
 

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Discussion Starter · #6 ·
okay so I got the truck running after many cycles off the key.. I bumbed the start a lil to get lift pump to run for like 30 seconds or whatever and for a long time it had like 1 psi and sounded weird then all of a sudden it sounded normal and went up to 18 psi.. the whole time I had couple injectors cracked and id role it over a lil.. does that sound normal or is lift pump going bad.. just thought it was weird all of a sudden in got pressure but it still took for ever to get it started
 

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definitely vapor locked it, bleed the fuel system by opening the injector lines and priming the pump. I believe they're 3/4"
haha 19mm bud. Its a Cummins.

I know, I know, same wrench right, but as someone who turns wrenches for a living there are times that the interchange does not work, not worth rounding corners is my point.
 

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????? Sounds weird all together but I would make my focus on something with the lift pump more then the injectors etc. Because the motor starting up would not affect the pressure from your FASS in any way. I would still check the plastic ball and spring that is behind the return line on the FASS. It's easy to check and if the ball or the spring gets worn it can cause those kinda issues. The guys at FASS told me that cavitating is hard on that check valve setup and often happens when the tank is ran low on fuel and they recommended i don't ever run below a 1/4 tank.
 
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