Engine/Transmission (1998.5 - 2002) Fass installed fuel press. fluctuation

[Aaron_A]

I just installed my FASS system,and it seems to work very well and is a very nice system. My question is,my fuel pressure gauge is very erratic. The needle sweeps back and forth from 14psi to about 17psi. Sometimes it will stop and sit steady at 14psi to 15 psi, but then it will start the sweeping motion again.

This sweeping of the needle occurs even if the engine is not running (bump the starter and let the pump run)

Is this normal?

 

[BillGotthelf]

Sounds like you could have a small restriction in the fuel return line or maybe the fuel pressure spring in the Fass pump head is not seated. Give it a few weeks and see if it doesn't settle down.

 

[Aaron_A]

It only has about 20 minutes of run time. I will drive it to work in the morning and see what happens. Its great to hear the truck run again

 

[amillstream]

I haven't noticed it when my truck is off but when running mine will fluctuate from 13-16 and sometimes will sit solid on 15. Seems to stay more steady when the truck is warm though. Call Brad if you are worried about it. But from my experience, its normal.

 

[Uncle Jack]

Mine did that as well when I had the original fuel filter/water sep in-line with the supply and the gauge connected to the filter output. I felt that I may have had too much restriction in the supply line and/or a clogged filter. So, I bypassed the original filter assembly (at least until I get a new filter element) and moved the gauge fitting back to the FASS (allen screw on side near outlet to injector pump) via a copper oil gauge line from NAPA (2 lines connected together - 12 feet total). My cheap mechanical gauge is now rock solid at 17 PSI.

I was afraid that my in tank screen may have been clogged, but that was apperently not the case.

 

[TURBOs4LIFE]

Yes! Mine is also doing the same thing! I placed a snubber on my gauge to help slow down the fluttering. I would like to know why this is happening also.

 

[JKuehl78]

I don't have FASS but my Auto Meter Ultra Lite was doing the same thing... my engine ground was loose. I tightened it up and it's rock solid.