I drove my 86 tpi 305 for the first time after a few repairs and the car runs choppy. I have a BBK afpr that i think is the culprit. I turned the key on to test the pressure before I ran the car. I got it to read about 46psi key on which should be ok because my stock pressure was 44psi. I checked the pressure when the engine is running and it read 70psi! Would the too high pressure be causing my problems? My exhaust is a little white and the engine idled with a lope like it had a bigger cam. The needle would wiggle between 65psi and 70 psi. So I adjusted the bolt out as much as I could till it hit the plenum and I got a reading of about 55psi with the needle still wiggleing a little. When I take the vacum line off the afpr the psi goes to 60+. I tried to get a key on reading while the car was not running like I did before but it didnt work! The needle does not stay in place at 46psi like it did before I ran the car. The pressure will go up to about 22psi and then drop quick to zero 1 second after the fuel pump stops making its noise, it didnt do that before, whats up with that? I cant drive it yet because a heater hose just busted spraying coolant on me. I think I will have to take the plenum off and cut the bolt shorter to get it to run at 44 psi again. Advice please!!! What is the proper way to set this back to normal, with the key on or off? Whats the problem with my readings? Thanx!

 

ok, I did my homework and found this info on the site here:
Q: How do I correctly set the fuel pressure on my new adjustable fuel pressure regulator?

A: The correct way to adjust your fuel pressure is with the vaccum line of the fuel regulator disconnected. The instructions with many adjustable fuel regulators don't tell you to do this, but it is essential! You must remove and plug the vaccum line going to the regulator or you will be getting false readings, similar to adjusting the timing on vacuum advance distributor. What you are attempting to do is set the maximum fuel pressure. At idle, fuel pressure is reduced due to high vacuum, so the presence of the vacuum line is detremental to fuel pressure. Repeat the process until you have the desired reading.

So I guess I was doing my readings wrong with just the key on? I will try to adjust it back to a safe 40psi or so with the engine running and the vaccum hose off and pluged up. I have no Idea what my original running psi was since I only did the key on test.

 

Sounds like you have the correct method and a good ballpark number to adjust the fuel pressure.

The rail should hold pressure after you turn the key off. If it doesnt you have either a bad regulator(if the bbk is designed to hold pressure), a leaky injector, or a falty check valve in the fuel pump. You can check by clamping off fuel lines. The only one to really worry about is the leaking injector. That can do some damage. The other two will only cause longer crank times.

 

I believe stock psi on an 86 tpi is 36. At least that is what mine was. Follow the instructions you found and you should be fine. One note though...check the pressure often. I had to do it with mine. It kept changing periodically. Not much but enough to have to reset it.

 

Key on/engine off the FP should be 36/38 PSI.