Too high or too low - New FPR, bad idle
 

The diaphragm on my Mallory 4309 return style adjustable FPR went out last week. I replaced it with a new diaphragm from Summit along with a new pressure gauge to mount to the regulator. I adjusted to 5.5psi and went on my way.

The idle is now choppy and the car almost dies at lights while in gear. So, the question is, am I too high or too low at 5.5psi? Holley Street Avenger 770.

The only change to the car was the new diaphragm. Used to idle perfectly!

Re: Too high or too low - New FPR, bad idle
 

Bump

Re: Too high or too low - New FPR, bad idle
 

I'm dropping it to 4.5 tonight. We'll see what happens.... :(

Re: Too high or too low - New FPR, bad idle
 

Benn running good on 4.5psi.

I pulled the plugs just for fun tonight and they were close to white! Looks like I'm running very lean. Stupid question but does this have anything to do with fuel pressure? My understanding is that if you've got enough pressure to fill the bowls at all times you have enough pressure.

Jetting would be my issue correct?