Aeromotive FPR fluttering at idle
 

Alright guys, let's see if you guess what is wrong. Tomorrow I am going to swap to a different FPR to verify the fpr is bad.


Here is the informaiton.

I have an Aeromotive A1000 -6an FPR. I have had it for a few months (purchaed new). In total I have 700 miles on it or so. I have a single turbo and set the base fuel pressure to 40PSI. I have had flawless performance from it till today.

I was going on a cruise and from some earlier work today I didn't have the clamp fully on the intercooler pipe and the intercooler pipe slipped off. I went back to the garage, realigned everything and tightened everything up. All of a sudden my car wasn't able to start????????

I thought I flooded the car...I then realized I forgot to add back the "fuel atomization" vacuum line from the engine to the intercooler pipe and added that back on.

Got the car running and noticed that the FPR gauge is fluttering back and forth and was only getting 30-35PSI at idle with the vacuum line disconnected. I took the car out for a short drive and the car would run lean as more fuel was demanded. The car also shut off when the rpms would fall back down to idle with the clutch pushed in (low fuel pressure).

I tried adjusting the FPR and nothing happens. No pressure at idle is gained or lost no matter how much I turn the regulator. When the car is shut off the gauge goes to 0 PSI. I used to see pressure hold between 20-30PSI for a good while after the car was shut down.

Also during adjustment, I was watching AFR's during idle.....no adjustment changed my AFR's on the regulator. I have a liquid filled FPR gauge and I don't think that is the problem. I am still using the supra pump that has like 8-10K miles on it from the previous owner. My fuel filter is OEM and has 700 miles on it.

700 miles on this FPR, that's it. Think its bad? It is only 5 months old from my purchase date and I believe it is still under warrenty.

at idle I am pulling -22 inches of mercury (I am at elevation). Spark plugs are 9's all around with 700 miles on them.

did you rewire you fuel pump yet. the factory fuel pump resister will give unstable fuel pressure reading when you start modifying the fuel system. also check the fuel pump assembly for bad connections. the aeromotive regulators are very reliable,not much can go wrong with it.

I had this problem when I first put in my Aeromotive A1000 -6AN because I used the wrong fittings.

I used -6AN male flare to male flare fittings and the conical seat is too long on the side ports and it hits the internal mechanism of the regulator. You have to use the correct -6AN port fitting without the conical seat for the flare or cut that part off the fitting if you don't mind raw alum in your fuel system (ie, not running alcohol).
https://www.rx7club.com/attachments/...g-idle-6an-jpg

I used -6AN O-ring fittings for the FPR.

The fuel pump is a supra pump and it is wired directly to the battery.

The pump was purchased like 10K miles ago and I recently installed a single turbo. I tuned the car and its been through some hard pulls for tuning. It was probably a tired fuel pump to begin with.

I think its the fuel pump after doing some research. The fuel pressure regulator in the vacuum line does not smell like gas, and the FPR goes straight to 0 after the car is shut down, which means the fuel pump isn't holding the pressure.

It used to hold 20-30PSI after shut down for a long time.

I have a new fuel filter and the old one was only 15K miles old but had some years on it.

Here is what the fluttering looked like on a different car.

When I rev the car up it stumbles. I did a small test drive and the AFR's climbed as load climbed....I think the pump was only outputing 35PSI the whole time.

Video of how my car acts when shut off (someone elses car)



My needle flutters when idling a lot (it is a liquid gage). It used to be rock solid.

The car has been driven a lot with the supra pump rewired, I doubt the wiring is all of a sudden bad. When I key the car on, I don't get any priming of the fuel system, it goes from 0 to pressure just like the clip above.

supposed to look like this.


Vacuum at idle is -22 in-hg. Normal for where I am at.

I wanted to report my findings for anyone who has this issue in the future. I did some tests to see if it is the fuel pump.

I turned the pressure on and blocked the fuel return line and then turned it off. (squeezed the hose) and the pressure goes straight to 0 like a sprinter with the hose squeezed. The check valve in the fuel pump is bad. I squeezed the return line while the pump was on and it could only reach 30PSI. It's a weak fuel pump as well. The fuel pump is toast and I am replacing it.