Recently I have been noticing everytime I start my truck the FASS pressure varies. Sometimes it is at 15 psi and sometimes i've seen it around 6 psi. These numbers are while the truck is idleing. I have since changed both filters and nothing has changed. What do yall think? Could there be a problem with my diaphram for the fuel pressure gauge? Thanks

 

Mine did the same thing. I thought it was the isolator. I tried to take it apart, but couldn't get it to split open. I put the line back on and all was well. I think I had a cut line from over tightening.

 

Mine did the exact same thing a couple times now. I just mess around with the wiring from the sender and all is back to normal....

 

Where is your "T" at or do you have a filter lid replacement?

 

I run the FASS system so it already has a port on the unit itself.

 

Allrighty then lets clear this up, that is way too much psi difference. So you are running what size line, from the fass gauge port to where your isolator is and how far is it(mechanical gauge) ? Or are you using a electrical gauge sending unit? More info needed here... what make of gauge?

 

I'd bet it's just in the sender. Mine did the same thing a couple times now and, as I said, just messing with the wiring fixed it. My symptoms were Exactly as he said his are....

 

Wow, are you running a line from the port on the FASS all the way to an isolator or gauge in the engine bay? If you are, did you bleed the line?

 

Yes ive bled the line, the gauge used to read 16 psi but lately it has dropped to 7psi after my 3000 mile trip.

 

Did you try redoing the end's. Are you using an isolator.

 

check your brushes in the pump