I installed my gauges this weekend and it went quite well. I have one question though. I installed the FP gauge and I am reading really low pressure. Do I need to get the air out of the line that goes from the isolator to the gauge? I assume that since air is compressible that the reading I am getting 7at idle, 4 at 2000 rpm and 2 at WOT, are falsely low readings.....I hope....

 

I built a gauge kit that I can use on other peoples trucks and used clear tubing for the fuel line. I've never seen the fuel actually get within a foot of the gauge.
I have an Isspro mechanical gauge in my truck and I checked it against the temporary gauge. They both read the same. Sounds to me like your lift pump is going bad.

Hopefully other will chime in here that use isolaters-

 

The compressibility of air will NOT cause low readings. If anything, this will help to dampen the pulses from the VP.

Think about it: if you weigh 200 pounds and sit on a spring that compresses 3 inches, how much force does the ground see: right 200 pounds.


Justin

 

In either case, it won't take long for the air to get out of the line all by itself. I had about an hour of run time with my gauge installed, and I wanted to see how much fuel my needle valve was letting get to the gauge. I took the line off at the gauge and bumped the lift pump......and no air at all.

Boyd.

 

You've got a bad lift pump. Don't worry. It's a normal thing. They die all the time.