3rd gear pull

*Update

I heard my inline pump making intermittent noises, seen my fpr gauge jumping around +/- 4psi both ways. I checked all the connections and found a bad ground on the inline pump.

Now my fpr is stable, problem is i can get 43.5 base pressure with activated pumps on link. But when i start the car base pressure rises to about 50psi.

I tried to set base pressure with the car on and vac. Line unhooked but my base pressure will not go lower than 50 and it doesn't change with the vac. Line off or on, it will stay at 50.
I doubt im over running it? If i get time today i will remove and check the diaphragm and ball seat.

** I had free time at work, i took apart the fpr and the ball doesnt seat perfect( although better than any pics ive seen online). The diaphragm was good.

Sadly, I can not look at logs while I am at work.

As for base fuel pressure, does link activate both pumps? What voltage is going to the pumps with the car off vs car running? What size line are you running for your feed and returns?

Yes, Link activates both pumps.
Car off: 11.6v
Car idle: 13.5

I have -6an feed from tank to rail/ rail to fpr.
I believe i have a 3/8th line from the fpr to the stock hard return line.

The fpr is the aeromotive compact.

The fuel is making it to the rail but there is a restriction causing isuues geting it back to the tank. There are a few possible causes.

First the gauge could be faulty. Does it increase if you screw the adjustment screw in?

Secound is a malfunctioning AFPR.

Lastly there could be a restriction between the AFPR and the tank, causing a backup. If you attach a shorter length larger in diameter line going to a bucket, can you get the pressure to go down?

The jump from not running to idleing could be from the 2volt increase but not being able to lower the pressure is an issue from the AFPR to the tank.

I threaded the adjustment bolt all the way down and even un-threaded it far enough that it came off and there was no change in the reading. I do see some fluid leaking out of the gauge.

I will try dumping the return line in a bucket and post the results.

If the base pressure is actually that high, i figure i would have a rich issue instead of a lean issue.

You are overrunning the siphon

1996dsm said:

I threaded the adjustment bolt all the way down and even un-threaded it far enough that it came off and there was no change in the reading. I do see some fluid leaking out of the gauge.

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This leads me to believe either the regulator is not adjusting pressure at all or the gauge is bad.

Remove the VAC line, hook up a regulated air source to 25PSI and turn the pumps on via link. Now observe the gauge and apply the regulated pressure your fuel pressure should go from 50 to 75PSI. If this is not the case, you might want to look at the diaphram again.

Is the fluid that you see leaking fuel or fluid from inside the gauge face? Tighten the gauge if its fuel replace the gauge if its fluid from the gauge face.

1996dsm said:

I threaded the adjustment bolt all the way down and even un-threaded it far enough that it came off and there was no change in the reading.

Click to expand...

jery1234 said:

You are overrunning the siphon

Click to expand...

If this was the case, you would be able to raise the pressure. Turning the AFPR adjustment bolt in would cause the pressure to rise and that didn't happen to the OP.

The gauge is leaking the oil from the face.

Only regulated air i have is a HF 2gal. pancake compressor, i have no faith in it's accuracy.

I picked up some hose just now, I will hook it to the fpr and see if anything changes.

With the hose on the fpr dumped in a bucket, pumps activated i set the base fp to 43.5psi. I started the car and it kept the same pressure.

I installed the fpr return line back to the factory return and with the car off 43.5psi with the car on 50psi. I threaded the fpr adjustment all the way in and got about 60psi

The fpr also drops all fuel pressure instantly as the car is shut off.

1996dsm said:

With the hose on the fpr dumped in a bucket, pumps activated i set the base fp to 43.5psi. I started the car and it kept the same pressure.

Click to expand...

This sounds like your return line is insufficient for the amount of fuel you are trying to bypass or you have a clog somewhere along the way.

1996dsm said:

I installed the fpr return line back to the factory return and with the car off 43.5psi with the car on 50psi. I threaded the fpr adjustment all the way in and got about 60psi.

Click to expand...

1996dsm said:

I threaded the adjustment bolt all the way down and even un-threaded it far enough that it came off and there was no change in the reading.

Click to expand...

These two statements contradict eachother. So when adjusting out you still can not get the pressure below 50psi with the car running but you can get the pressure to increase?

Car on With the return line hooked up i got a max of 60psi if i thread the adjustment bolt all the way in, if i unthread it all the way it stays at 50.

When the return flows into the bucket it stayed at 43.5 with the car on and off.

Ive ran this same fuel setup for about3-4yrs, although the 255hp replaced a 190 about a year ago. I remember the base pressure being achieved.

Ive ran e-85 for about 3yrs without a tank of pump gas in between. Maybe a tank of 93 would do some cleaning and give some progress.

For the most part we were able to correct AFRs before 5k. They need another pass but with the new found fueling issue we will have to re-due things anyway.

Even with the inflated VE values your car goes lean right at 5k. The boost varies slightly at this point but even telling the computer to add fuel, it can not do so. Your about 16.5% lean around 6400rpms. Your running out of fuel (possibly the bad ground).

1996dsm said:

Car on With the return line hooked up i got a max of 60psi if i thread the adjustment bolt all the way in, if i unthread it all the way it stays at 50.

When the return flows into the bucket it stayed at 43.5 with the car on and off.

Click to expand...

This points towards a restriction in the return line. It would probably be best to start a new thread to discuss this further if you don’t find the problem.