My truck has a low pressure dummy light mounted on the injector pump. I'm not sure what pressure it is set to but started flickering every time I got on it. I replaced the lift with a fass platinum 95gph. It helped a little but am having same prob. When It first started I noticed my tank had vacuum on it when I remove the cap so I drilled a hole in it for now. Also I have a van aaken pump programmer. I'm driving a hour and a half one way to work six days a week and would appreciate any input befor I ruin my injector pump.

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I am planning on buying a fuel pressure gauge to see exactly what I've got going but won't have it for a couple more weeks.

 

Typically low pressure lights are 3-5 PSI which I can say is way too low and VP44 damage is being done.

Time to buy a fuel pressure gauge and install it before you ruin your VP44...

Tank vent plugged up on the fuel sender?

 

Not sure do I need to drop my tank to look

 

No. You can usually crawl under and look at the sender top and see if the vent tube is plugged with mud or debris. It a small thin nipple on the top of the sender.

 

Do you think that could cause my pressure problem? Just pulled my truck into the garage to look into it. Thanks

 

If the vent isn't working properly then yes. Eventually the lift pump can no long pull fuel from the tank because the vacuum is exceeding when the lift pump can pull. (tug-o-war).

 

Look at your diagram for supply and return lines from the fass pump you probly have the supply and return lines in the wrong locations. The truck will start and run on the fuel that is being returned from the fass pump if they are swapped and pressure will read around 3-5 psi. It will also pressurize the fuel tank

 

Tank was pressurizing before I changed the pump, I did just go out and double check on the lines though. Dropped the tank and it was clean and draw tube was clear. Taking it to the dealership in the morning. They said it sounds like the injection pump or the injectors.

 

It could be possible the injector pump or injector is failed. does the truck start ok? Excessive smoke? (white or black)

 

Hopefully that help, it is #6, Rollover valve