2000 LS1 A4 Torquerv2 CAM
36lbs injectors
I have a fuel pressure gauge at the rail that reads 50PSI at idle and with key on
fuel pressure slowly goes down when key is off
fuel pump was recently replaced with a precision pump assembly
currently have a microgard fuel filter
Engine runs rough with some hesitations I’ve read online PSI needs to be at 58
any suggestions to resolve fuel pressure?

 

Start the engine and check pressure while running. Those little gauges are known to not read right especially when things warm up

 

Yes while the engine is on the PSI stays the same at 50-51

 

Can you try a different gauge??

 

The most likely culprit. The stock FPR is designed to maintain 58 PSI. If an aftermarket or incorrect FPR was installed (especially if it's adjustable and set wrong, or a fixed-rate one from a different application), it won't hold the correct pressure.

 

I put a 2000 trans am fuel pump from precision from oreilys with the built in FPR

 

Never heard of that pump assembly so can't comment on the quality of the pump. Fuel pressure dropping once the engine shuts off shouldn't be a concern but only having 50 psi should be when you should have 58 psi so that could mean fuel starvation which is bad. The fuel filter could be too restrictive also. The FPR is built into the pump assembly but if it was me I'd start with changing to a stock fuel filter and see if that resolves the issue. Have you had it tuned for the new camshaft?

 

Yeah the filter is from a 2007 ford 5.4 and I believe it’s a 12 micron while the stock micron level is 17 so idk if that’s a issue

 

I need a corvette style filter but WITHOUT THE REGULATOR so I went with a 2007 ford 5.4 cause it fit the same with the 3/8 inlet and outlet and 5/16 return line
my car was a v6 before it was a v8

 

You had a V6 car so it has a feed and return line up to the front of the car correct? Was the fuel pump assembly purchased from like O'Reilly's and was for the V8 car? The factory pumps have a built in FPR. The fuel filters like the C5 Corvette have a feed and return line built into them which meant it had a built in FPR. I have one of those on my 01 car and when I was running a factory style fuel pump assembly I had to remove the FPR from that pump assembly. Just wondering if the fuel filter you currently have which has the 3/8 feed and 5/16 return is similar to the C5 Corvette fuel filter and if it is then you'll have to remove the one from the pump assembly.

 

Yeah I bought a v8 pump from oreilys with a built in FPR and I wanted to remove it because I have a spare corvette filter but I couldn’t figure out how to remove the FPR from the assembly