Nomo47rh

Sorry if the answer is posted somewhere else? I’m new to this site and think I did an extensive search without finding answers? Same issues but lower pressures I have a 95 ram. 315km. (196k miles). Almost stock. Tork Tek OFV. #10 fuel plate. It was an auto And I converted it to nv4500. 160 hp p pump. Fuel filter new and rubber line from lift pump to heater new. fuel heater eliminated and screen cleaned. Truck runs really well but when i get on it and it’s start to come hard into the boost the fuel pressure drops to about 15lbs and then comes back to over 30. Idles at 22 PSI. It still pulls hard but as long as I’ve had a fuel pressure gauge it has done this. Ive since added the fuel plate changed OFV fuel heater delete and fixed cracked steel return line. (All made big differences.) It’s always done this so not sure if it really effects performance? Hits 30PSI boost. Have not changed lift pump or the little screen going to the lift pump yet. Is this normal? I have a lift pump but don’t want to change it if I don’t need to. If the answers are out there please point me in the correct direction or explain how to do the search properly. Thanks In Advance for answers. Only had it 3 months but Love my truck. Gets better fuel mileage towing our 24 ft 5th wheel then my f150 got empty and it has obscene torque.

Nomo47rh

Also I do t think it’s the lift pump cause fuel pressure would not recover. But I also didn’t think a leaky return line would fix any issues either.

Nomo47rh

Any body?

texasprd

I can't say if the temporary pressure drop is normal or not - if I'm hard on the accelerator, I'm not looking at my FP guage since it's down by my knee... With 22 psi at idle and 30 at speed, I wouldn't be looking at the lift pump right away. Probably not the OFV either, with those pressures. Just to "check the box" (so to speak), have you tried pinching the return line to see if pressure jumps up?

Is the 30 psi while you are still under hard acceleration, or is that in steady cruise mode (what RPM)?

I would definitely check the pre-filter. Also, how long has it been since you replaced the fuel filter? I'd also consider checking the tank and seeing if you have anything growing in there and covering or washing up against the screen around the fuel pickup (someone on another forum encountered that issue).

PMed you...

NJTman

It's well known that the ve pump (1993 and earlier) will suck the FP down when a load is applied. If I whomp on it, I can pull my normal 8 to 10 psi down to zero, and my fuel pump is brand new from Cummins. This is the,reason why guys have upgraded to the HVLP pumps from the aftermarket world.

I can only assume that other injector pumps (such as yours) react similarly based upon their functional purpose..

Nomo47rh

texasprd. I have not tried pinching off the return line yet. I’ll try to get on that tonight. Fuel filter was done about 10000km ago. 6000 miles. At about 1750 it pegs the gauge at 30PSI. If I step on it there once it hits about 15-20 PSI boost the FP drops to about 15. It comes back by the end of the gear. I don’t rev it much past 2500 cause it has stock valve springs. I can only say this for 4th and 5th gear cause the others are to short to look when I step on it. I was planning on dropping the tank to put new fuel lines in this winter when the trucks off the road. How can tell if anything is growing in the tank? Thanks a lot.

Nomo47rh

NJTman. Thanks. That’s what I’m hoping. Cause it otherwise runs great.

texasprd

I'm starting to lean toward that being normal behavior. I did lean on mine moderately this morning - fuel pressure dropped initially, but came back quickly as RPMs climbed.

If you have algae in the tank, I imagine you'd likely see it on the module if you pull the module - and look in the tank with a good light. My understanding is tank schmoo usually isn't an issue unless the truck has been sitting a while.