Fuel pressure under load?
Thread Starter
|
Tuned
Joined: Feb 2005
Posts: 380
Likes: 1
From: ohio
Fuel pressure under load?
Still working with some drivability issues and other quirks in my 97. Decided to install a fuel pressure gauge where I could see it while driving. Truck has 55lbs (middle of needle bounce) at idle and 60 when you bring the RPMs up above idle. Going down the road at 1500 to 2000 RPM in 4th gear if I mash it the pressure drops to 40, if I set the chip up to the first notch (heavy tow, cant remember the HP), it drops to 30, if I set the chip to the next higher (I think 50HP) higher it drops to 20. Truck has Rosewood 1s and a T-S chip with PHP tunes that are pretty aggressive and a S-D pump. Do these pressures sound OK or not? Fuel sytem is stock, filter is new, gauge is plumbed in at schrader valve. I plumbed a clear line into the return line at the filter to check for bubbles and there are none. Sorry if this is often posted I couldn't find it via search.
Posting Guru
Joined: Jan 2003
Posts: 1,412
Likes: 0
From: Munroe falls, Ohio
All I can say is that with a new mech pump, I can drop fuel pressure down to 30 from 65 with stage 1 and the hottest tune. I asked this same question a month ago and no one could answer if dropping fuel pressure this low would hurt injectors or lose power
PREMIUM SPONSOR
Joined: Sep 2003
Posts: 2,630
Likes: 217
From: North East Ohio
I don't think you'll cause much damage with pressure that low, but you are certainly loosing power.
You want a rock-steady 65 psi.
I dynoed years back changing fuel pressures and 10 psi under 65 lost like 10 hp, and 10 psi over 65 lost about 10 hp. You want to be right at 65 allthe time.
So if you're dropping more than that you need to get more fuel pumping.
If it's 50 at idle, shim to 65 and re-test. It should at least bring your low numbers up a bit.
You want a rock-steady 65 psi.
I dynoed years back changing fuel pressures and 10 psi under 65 lost like 10 hp, and 10 psi over 65 lost about 10 hp. You want to be right at 65 allthe time.
So if you're dropping more than that you need to get more fuel pumping.
If it's 50 at idle, shim to 65 and re-test. It should at least bring your low numbers up a bit.
__________________
'96 7.3 F-350 Reg Cab 4x4 - bought new.
'04 6.0 E-350 custom 4x4
'08 6.4 F-550 Reg Cab 6 spd 4x4
'17 6.7 F-250 KR ccsb 4x4
'96 7.3 F-350 Reg Cab 4x4 - bought new.
'04 6.0 E-350 custom 4x4
'08 6.4 F-550 Reg Cab 6 spd 4x4
'17 6.7 F-250 KR ccsb 4x4
Thread
Thread Starter
Forum
Replies
Last Post
iverger
1994.5 - 1997 7.3L Power Stroke Diesel
2
Jan 18, 2015 05:50 PM
Jeepincj7
1994.5 - 1997 7.3L Power Stroke Diesel
6
Dec 24, 2011 03:47 PM
