stock99

Just installed an Isspro Fuel Pressure gauge w/ isolator, works great but when truck is shut down the guage reads 3-4 PSI, even the day after, is this normal......

BarryG

I don't think that is normal. At least on my truck if the truck isn't running there is no pressure.

stock99

any ideas what could be causing this, at idle it reads 15-16 psi just installed a new lift pump when installing gauge, (thats how i found the bad lp) so i think it is reading correctly

RowJ

Sounds a little high on both ends. My Isspro reads 0 at shut down and 14.5 at idle with new pump. Gauge calibration? You might hook up temporary gauge under hood to compare readings.

RJ

Dr. Evil

I believe you problem is likely due to the isolator - they are notorious for causing inaccurate readings.

Try temporarily bypassing the isolator to zero identify the problem.

stock99

UPDATE - went home over an early lunch, craked screw on fuel side of isolator, gauge went to 0, restarted engine filled line shut screw, 15+ psi, shut off engine gauge went to 4 psi, craked fitting on gauge side of isolator, gauge went to 0 psi tightened screw restarted enginge gauge reads 15+ psi shut it down gauge went to 0 psi, repeated for good measure same results think i got it fixed......

sorry if this posts twice i was having difficulty

stock99

cracked is the word is was looking for, not craked....so much for a college education

Dr. Evil

probably some air in the line......