Here's the deal: I have a high pressure walbro GSS340, stock fuel pressure regulator. Ever since the fuel pump install, my fuel pressure is 52 psi with the vacuum line off, about 47ish psi with vacuum line on. Obviously way too high. I was going to order an AFPR and put the pressure back to where it should be, 43 psi, but my buddy who tunes my car said "no, I can adjust the tune to compensate for the higher pressure". What would you guys do, leave the high fuel pressure, or just get an afpr and put the pressure back down where it should be? 2 reasons why I want to change the regulator: I've heard that running a high pressure like that can cause premature failure for the fuel pump, because its making it work harder. But then again, I also have the "high pressure" walbro, prolly should be able to handle 52 psi no problem...The other reason is, shouldn't my stock regulator be keeping the pressure at around 43 psi (give or take 10%) no matter what? If so, why is it at 52 psi? Bad regulator?

 

I'd like to know this too What is the best fuel pressure for performance and/or reliability?

 

Honestly, I would change the regulator and tune it right. yeah it's a pain, but at least you know that the cars within prescribed parameters at that point.

 

Thats exactly how I feel, but my friend insists that he can make it work with the high pressure. Just looking for a few more opinions, and i'll make my decision from there

 

The reason you are seeing such high FP after the regulator is because the regulator is bad. If it is letting a consistent 7-9 PSI "bleed" past it, it will continue to get worse. He may be able to compensate for the higher fuel pressure for now..but the car will never run like it should because the regulator will get worse with time.

I'd replace the regulator and go from there.

 

We actually thought about doing that to my car. I had a lean condition up top with the new setup, and the mechanic and I contemplated using an AFPR to fatten her up, but I decided no, I'd rather the car be running on the right pressure and a more dialed in tune.

 

Noob question here: How does lowering the fuel pressure help? My car was running 20 PSI and ran like crap.. i replaced the fuel pump and now she runs great at 40 PSI with key in the ignition, and 2-3 less in idle. What exactly happens when the FP is too high or too low? Just trying to understand.. thnx

 

I had the same issue. An aftermarket fuel pump left my pressure about 4-5psi high. I chose to use an AFPR to bring the pressure back to stock levels. But I don't know which of the two options is better, actually.

Toby, the computer is tuned assuming a specific pressure. So the car's going to run best when the pressure is actually the same as what the computer thinks. Replacing your pump brought it back in line. The O2 sensors will of course also recognize a problem and the computer will try to adjust even though your pressure is off, but I suspect there's only so much the computer and the cheezy O2 sensors can do, if the pressure's wrong.

Dave