I recently swapped out my Aeromotive AFPR for a Fuelab AFPR. Never had an issue with the Aeromotive as fuel pressure was always rock solid. Once I put the Fuelab on fuel pressure is very erratic. It varies greatly depending on if the car is cold or warmed up.

Example: I pull the vacuum/boost reference line when I first start the car cold and set the fuel pressure at 43.5psi and then drive somewhere. When I get there pressure with the line removed has dropped to 35psi. So I readjust the pressure to 43.5psi with the reference line removed. The next time I go to drive the car I check the fuel pressure when cold again and it's 50psi with the line removed. What the heck is going on here?

The Fuelab regulator has only been run with 93 octane, doesn't leak fuel anywhere, and has maybe 3000 miles on it. As I stated before the pressure was always spot on with the Aeromotive, never changed if it was warm, cold, frozen, on fire, etc.

Obviously I can solve the problem by going back to the Aeromotive, but should I disassemble the Fuelab and see what's going on in there? It seems that if the regulator were to fail fuel pressure would most likely be too low or fuel would be leaking out the reference line. Did I maybe just get a wonky regulator? The only thing I can think of is the seat might not be sealing correctly all the time or something is distorting due to heat.

Any help is appreciated. Thank you.

 

Sounds like it's having a temperature related issue. Bad diaphragm or spring is possible. Need to take it apart..

 

That was my assumption. I'm unsure what to look for when I take it apart other than a diaphragm that is bad. It has been like this since I got it. I had it on a previous car which displayed the same problem, but I didn't think a new regulator could just be bad. Sucks...

 

contact fuelab, and see if they will replace it under warranty or maybe provide some troubleshooting info.

 

I have the same problem with my Fuelab pressure regulator. Let me know if you can fix it please!

 

I have since pulled the regulator off and could find no flaws internally. Diaphragm was good, no rips. Everything was clean. All machined parts were clean, no burrs or odd edges. I am thinking now that it may be a problem with the fuel pressure gauge. I plan on testing a new one and reporting back.

 

Has the fuel pressure gauge been on two cars too?

 

Yes. I just transferred the whole fpr w/gauge over

 

Suggest you stick the Aeromotive in with the gauge and see what happens.