Fuel Pressure Testing - ZR-1 Net Registry Forums

Locobob · 11-02-2016

So I've been driving around with a fuel pressure gauge taped to my windshield trying to sort out some drivability issues. Here's what I'm seeing:
42psi at idle
Usually jumps up to about 47-48psi if I hit the throttle hard, but a couple of times it actually dipped a little first.
Drops to about 38psi briefly when I drop the throttle out rapidly after gunning it.
Around 40psi at light throttle cruise.
Anyone else do this and what did you see?

Also left block learn is higher than right, about 144 at idle vs. 128

Interestingly the car seems to be driving fairly well today, not noticing the issues I was having in the last weeks. It is very dry here today while it's been pouring down rain for the last few weeks, I wonder if that has anything to do with my rough running issues. Hmmm

mike100 · 11-02-2016

does it hold 48 psi beyond 5500 rpm? 50-52 is what both pumps in tandem should achieve, but maybe allow for a fudge factor if your gauge isn't super accurate. In my case the pressure went up to spec (50+ psi) when you stepped on it and the secondaries were open, but since one pump was weak, it dropped to 45 psi by 6500 rpm.

11-02-2016	#1
Locobob Join Date: Jan 2004 Location: Portland, OR Posts: 1,057	Fuel Pressure Testing So I've been driving around with a fuel pressure gauge taped to my windshield trying to sort out some drivability issues. Here's what I'm seeing: 42psi at idle Usually jumps up to about 47-48psi if I hit the throttle hard, but a couple of times it actually dipped a little first. Drops to about 38psi briefly when I drop the throttle out rapidly after gunning it. Around 40psi at light throttle cruise. Anyone else do this and what did you see? Also left block learn is higher than right, about 144 at idle vs. 128 Interestingly the car seems to be driving fairly well today, not noticing the issues I was having in the last weeks. It is very dry here today while it's been pouring down rain for the last few weeks, I wonder if that has anything to do with my rough running issues. Hmmm __________________ Robert ZR-1 Net Registry Oregon State Director 91 ZR-1 #431 Black/Black LPE 368

11-02-2016	#2
mike100 Join Date: Feb 2011 Location: San Marcos CA Posts: 1,802	Re: Fuel Pressure Testing does it hold 48 psi beyond 5500 rpm? 50-52 is what both pumps in tandem should achieve, but maybe allow for a fudge factor if your gauge isn't super accurate. In my case the pressure went up to spec (50+ psi) when you stepped on it and the secondaries were open, but since one pump was weak, it dropped to 45 psi by 6500 rpm.