I recently installed an Aeromotive AFPR....the car has been staring hard lately (lots of cranks first)....I thought maybe it was my spark plugs (perhaps fouled??)....but then I had someone watch the gauge when I turned the key to on, but didnt start it. The fuel pressure goes right up to 40psi when I turn the key, but then it quickly drops down to 0. Why would it be losing pressure like that?? I dont think I have any leaks.... Thanks

 

I'd suspect the Aeromotive AFPR; my friend installed a new one and the first time we adjusted it, his O2 readings were all over the place (on dyno with wideband O2 sensor). Replaced it and the problem was fixed. Pull the vacuum line off the AFPR and see if it leaks fuel. The other cause could be a faulty check valve in the fuel pump.

 

Well it is one heck of a coincidence that this problem started after I installed this regulator. I have checked to see if it leaks fuel, and it does not. I guess I'll just have to turn the key quick after i turn it to on, while there's still some pressure in there....

 

I have heard that AFPRs do not hold pressure after the pump shuts off. When turning on the ignition, the pump only runs a few seconds, then shuts off, right? So..it is dropping pressure after the pump stops?

I swear I've heard this type of thing before. I'll do some hunting for more info.

[edit] it is sounding more and more like the check ball in the pump... check out this link. You might want to try to put a pressure guage right on the fuel filter and see if it holds pressure there. If it doesnt, its time for a new pump. If it does, you have a leak up front somewhere like an injector ar the AFPR.

http://www.f-body.com/forum/showthre...r&pagenumber=2

 

http://shbox.com/1/4th_gen_tech2.htm...essure_testing

Here's a how to on Shoebox's site.

On my 94 the steel gas lines to to a rubber by the drivers shock tower. I pinched them there.

 

Some aftermarket AFPR's are designed to bleed down the pressure after shutoff to relieve the pressure on the injectors. I have a Weldon AFPR that does that, but it doesn't drop the pressure to "0" immediately.... takes a minute or so for it to bleed down. Car starts fine as long as you start it within 10-sencods or so of the pump shutting off. But that's not one of the AFPR's that bolts into the back of the rail, its a stand alone unit.

I would wonder why Aeromotive would design a stock-style replacement that way, and if they did it intentionally, why they would have it bleed down immediately in a system that shuts off after the first two seconds, waiting for you to start the car. Sounds more like a problem with the AFPR to me.

There seems to have been a lot of posts over the past few months complaining about the Aeromotive unit.

 

The fuel pressure takes about 3-5 seconds to drop all the way down from 40 to about 0-2 psi.....There is no gas coming out of the vacuum line....I changed the fuel filter and it seemed to get a little bit better. I dont know what to think...

 

OK I was just outside in the cold for about 2 hours. I took off the Aeromotive AFPR and noticed it had been leaking out where it connects to the fuel rail (the connection on the Aeromotive screws in and came loose)....so i put some threadlock on it and tightened it up real good, put it all back together, and it still wouldn't hold pressure. So I took it all apart again and put the stocker back on. It now holds a constant 40 psi of pressure!!! So this proves the Aeromotives are just an absoloute waste of money...I don't know if its worth it to get a new AFPR, any of you suggest it or no? If so, what kind is the best?? (I've already gone through a Caspers Electronics and an Aeromotive)....Thanks!