I thought it was the pump so I changed it. Didn't help. I am running the VaFPR WITHOUT the vac line hooked up. I have an inline FP gage mounted in the rubber hose by the power steering pump. I set the FPR for 13lbs last week when I installed the fuel pump. Tonight when I got home it was 14, I started the car an hour later and it was 10lbs. I waited 15 minutes and tried again and it was 11lbs so I drove it arround the block and checked it, 12lbs this time. I have checked the voltage using WinALDL and it is 13.3/13.5 volts in the system (not varrying much). I thought it might be weather related be cause we have been in a heat wave but today it is about 70* outside and I'm still having the same problems.
Need to figure this out so I can finish prom tuning. Right now I cant tune the BLM's because they won't stand still.
Any ideas?

 

I would be tempted to say it is EITHER the regulator or the guage itself. I can't think of anything else.

My fuel pressure is always 15psi (where I have shimmed it from the stock ~12 or ~13), hot, cold or whatever.

 

My Jegs liquid filled gauge has absolutely no temperature
compensation. As it heats up the indicated pressure
drops like a rock. I figure that pressure building
up inside the housing is changing the calibration.

I spent a lot of time working with fuel pumps and regulators
until this came to light. Try hitting the gauge with a
hair dryer and watch the pressure.

kevm14, I would be grateful to know what gauge you are
using for fuel pressure readings.

RBob.

 

Thanks guys. RBob, I'll try that hair drier thing first. I have a cheap Summit gage , might be the problem.

 

My guage isn't fancy at all, just that AutoZone TBI guage. It was like $30 or $40. Can't really go wrong, and it comes with a T fitting to stick between your TB and the in-coming hard fuel line (well, it's hard on my car)...

 

I tried the hair drier and was abile to change the gage reading from 13 to 10 1/2 in about a minute. So maybe its just the gage.

 

It's not the cheapness of the gauge. I have the Summit gauge and an Autometer gauge. The Summit comes with no literature but the Autometer lit points out the indicated pressure will drop as the gauge warms up. Best thing to do is move the gauge away from the engine. I'm going to use the Autometer isolator and put the gauge in an Autometer pillar pod.

 

Thanks for the info kevm14 (and others).

What I finally did was to set the fuel pressure cold, then removed
the gauge. This way I didn't see that the indicated pressure was
way off (when it wasn't).

RBob.

Who considered removing the plug and draining the gauge.

 

Having the same problem and yes...I have a Jeg's gauge. I too just set/check the pressure when everything is cool and the motor has been at idle for just a few moments. It get's me in the ballpark figure and that's the important part, then I tune with eprom. Hence the whole "set it and forget it" mantality (spelling?).