need12v

Hello everyone, hope you're enjoying your sunday!
I finished up my gauge install this morning, and I went out for a test drive, only to find low LP pressure. I used a tapped banjo bolt, small brass valve, 36" hydraulic hose, and an isolator in the install. My pressures are as follows:
Starter bump, 11 PSI, after LP quits, it drops back to 0 quickly.
Idle, 10 PSI
Running 55 mph, no boost, flat road, 7.5 PSI
WOT, I got it down to 4 PSI.
I am led to believe it's the LP going south. Fuel filter was just changed about a week ago, and I have lookd at all the connections and such for a possible leak, and found none. Does anyone think air in the gauge lines would cause low readings, or do I just need to go to Cummins for a new LP? I want a FASS, but I just don't have the coin at the moment.

Geico266

You might want to double check the guage by buying a simple 0-30 w 1/8 NPT and test it under the hood at idle. Don't leave it on as the vibration will ruin it.

More than likely your LP is bad though.

I don't like isolators because they can give false readings.

FireMarshal3311

did you fill your guage and isolator before installing? If youdo get air in the line, it will compress and could give bad readings, so I would check the isolator up to the guage and see before I dropped a $$$$ on a LP if it ain't really bad.

Cory