Adjusting Fuel pressure
#1
Member
Thread Starter
Join Date: May 2004
Location: Texas
Posts: 305
Likes: 0
Received 0 Likes
on
0 Posts
Car: 1991 Z28
Engine: 350
Transmission: 700R4
Adjusting Fuel pressure
I have a 91 tpi 350 z28 with an adjustable fuel pressure regulator on it. Seems the fuel pressure may be low at idle. Not for sure though. Question is does turning the bolt on the regulator increase or decrease pressure and is it at idle or only under load ? Also is it 45psi the correct pressure ?
#2
Supreme Member
iTrader: (58)
Re: Adjusting Fuel pressure
Stock is 43psi IIRC. Turning in the screw increases pressure all the time. Set the base pressure with the vacuum line disconnected. The vacuum signal will alter the fuel pressure further as necessary under load.
AFPRs are a bit of EFI dark ages hokem. It's a bandaid workaround for not having the equipment or knowledge or $$$ to properly tune the car. A little tweak can sometimes help, but by and large most people are going to set it wrong and do more harm than good. IMHO.
AFPRs are a bit of EFI dark ages hokem. It's a bandaid workaround for not having the equipment or knowledge or $$$ to properly tune the car. A little tweak can sometimes help, but by and large most people are going to set it wrong and do more harm than good. IMHO.
#3
Moderator
iTrader: (3)
Re: Adjusting Fuel pressure
Seems the fuel pressure may be low at idle. Not for sure though.
Measure pressure - should be mid to high 30s.
Disconnect vacuum - should read 43.
if not....set to 43.
Reconnect vacuum...should drop back to mid to high 30s.
Last edited by Abubaca; 03-17-2017 at 10:38 AM.
#4
Member
Thread Starter
Join Date: May 2004
Location: Texas
Posts: 305
Likes: 0
Received 0 Likes
on
0 Posts
Car: 1991 Z28
Engine: 350
Transmission: 700R4
Re: Adjusting Fuel pressure
I put a gauge on and it sat below 40 so I turned it up to about 43psi and also took a handheld vacuum pump to the vacuum port with the engine off just running the pump and as I increased the pressure the fuel pressure went down. Is that correct because it seems to me it should be the other way around.
#6
Member
Thread Starter
Join Date: May 2004
Location: Texas
Posts: 305
Likes: 0
Received 0 Likes
on
0 Posts
Car: 1991 Z28
Engine: 350
Transmission: 700R4
Re: Adjusting Fuel pressure
Ok so the fuel pressure regulator is working properly. Apply vacuum and the fuel pressure is suppose to drop correct?