Does an adjustable pressure regulator affect the pressure at idle? I need to check my pressure because I think my fuel pump is on it's way out. I'm just not clear as to if the adjustable regulator I put on a few years ago affects the pressure at idle. Thanks guys!

 

Yes it does... the vaccuum will bring it down roughly 10psi, from your base setting, at idle. Do you have a pressure guage?

 

I've got a gauge. When I checked it last summer, it read about 39 psi at idle. I haven't checked it since, but I've got this "bucking" problem that I've done some research on and makes it sound like the pumps going out on me. I'm going to check the pressure tomorrow.

 

Stock PSI should be somewhere near 43.5 psi. The adjustable regulator does affect the pressure at idle like was mentioned earlier.

Hook up your guage and tape it to the windshield if you can so you can see it while you're driving and watch your fuel pressure as you accelerate. The pressure should steadily increase. If it drops at any point then you've definitely got a problem somewhere which could be the fuel pump or you could have a leaking injector. If you can smell a gas odor (more so than usual) under the hood of the car after driving it then you've probably got a leaking injector.

You could also have a clogged injector causing the "bucking"

 

a better way of doing it is to just adjust the throttle with your hand then driving it with the guage taped to your windshield

 

How exactly do you check the fuel presure, i want it between 48 and 50, but should you check it at idle or what?? I've also heard that you have to unhook a vaccum line???

 

So far, 3 l98's I have put AFPR's on, were all running stock at about 47-48 at idle... does this sound normal? Im beginning to think my guage is no good...

 

to set the BASE fuel pressure you have to unhook and plug the vacuum line going into the regulator. this should bring your fuel pressure up to its highest point.

typical pressures for the vacuum line ON are around 38 psi so dont worry. If you have a bucking issue then you are looking for a CHANGE in fuel pressure as the rpms rise that is not steady. I.E. you rev it by hand and the FP goes up steadily with the vacuum line on and then drops sharply or bounces around. that would definately cause some bucking.