Fuel Pressure Decreases with Throttle...
 

So I finally got my fuel pressure gauge all hooked up. It's an Isspro Ev2, and I also have the Tork Tek OFV020 Adjustable Overflow Valve. At idle, the gauge reads 25 psi, which is what Tork Tek states it should be. But as I give the engine some fuel, the fuel pressure decreases, instead of increasing.. I have not brought it to WOT yet, but bringing it up to just over 2k rpm, with about 10 PSI boost, the fuel pressure is about 20 psi...

My truck is all factory besides an Air Intake, and 4" Straight Pipe..

How old is the fuel filter? Could be a failing lift pump. A cracked fuel heater will cause a similar complaint with a hard start. The in tank module can also be restricted!

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When it is under a load it will drop. 20 psi sounds ok to me.

I guess i should have read closer. I saw 10 psi lol.

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So it's normal to drop fuel pressure under load? But the fuel filter is new, about 2k miles on it. I removed the fuel heater as well.

I was thinking it could be a failing lift pump, but I wasn't sure, Ill give it WOT and see where it drops to or if it stays at 20 PSI..

As engine rpm increases the lift pump produces more volume so it shouldn't drop much at all past 20. You could raise your baseline pressure up a bit more. If it drops when rpms are raised with no load then you should be looking for issues.

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