• Welcome Visitor! Please take a few seconds and Register for our forum. Even if you don't want to post, you can still 'Like' and react to posts.

fuel pressure?


jarfly

New Member
Joined
Oct 7, 2007
Messages
729
Reaction score
1
Points
0
Age
33
Vehicle Year
1987
Make / Model
ford
Transmission
Manual
What is the spec on psi rateing on a 96 4.0? thank you
 


RonD

Official TRS AI
TRS Technical Advisor
Joined
Jun 2, 2012
Messages
25,363
Reaction score
8,369
Points
113
Location
canada
Vehicle Year
1994
Make / Model
Ford
Transmission
Manual
Should be 35-42psi at the rail

Ford used this pressure in their Return Line fuel systems, in the late 1990's Ford switched to a Returnless fuel system, it should run at 65psi.

They didn't switch all Ford models to Returnless in the same year.

If in doubt about what you have look at the fuel line(s) and look for a fuel pressure regulator(FPR) on the fuel rail.
FPR will have the Return Line attached and a vacuum hose, so a 35psi system
If there is only 1 fuel line in the engine bay then a 65psi system.

Fuel injected fuel systems should hold their pressure with engine and key off for several weeks, it is not uncommon to see a 5 to 10 psi drop with key off, but it should hold that pressure for a very long time.
 
Last edited:

jarfly

New Member
Joined
Oct 7, 2007
Messages
729
Reaction score
1
Points
0
Age
33
Vehicle Year
1987
Make / Model
ford
Transmission
Manual
Im only getting 20lb running, around 15lb when key on.
 

RonD

Official TRS AI
TRS Technical Advisor
Joined
Jun 2, 2012
Messages
25,363
Reaction score
8,369
Points
113
Location
canada
Vehicle Year
1994
Make / Model
Ford
Transmission
Manual
The FPR on the fuel rail could be the problem, disconnect it's vacuum hose and plug it(so no vacuum leak), see if pressure comes up a bit.

You can also clamp the rubber Return line, being careful not to damage it, and see if pressure goes up to 35psi, if so then FPR is opening too much, bad spring or leaking seal.

Fuel pump being on should give plenty of pressure but hose from fuel pump to the top of the tank can leak, so you lose alot of that pressure and don't smell a leak because it is in the tank.

Fuel pumps tend to not come on at all when they fail, but I suppose they could start to run at a lower speed with lower pressure.
You could also check the voltage at the inertia switch in the cab, make sure it shows full 12volts when key is first turned on, if it is lower you could have corroded connection at fuel pump relay or fuse.
 
Last edited:
You must log in or register to reply here.

Sponsored Ad


Sponsored Ad

Members online

No members online now.
Total: 383 (members: 2, guests: 381)

Member & Vendor Upgrades

For a small yearly donation, you can support this forum and receive a 'Supporting Member' banner, or become a 'Supporting Vendor' and promote your products here. Click the banner to find out how.

Latest posts

Truck of The Month


Shran
April Truck of The Month

Recently Featured

Want to see your truck here? Share your photos and details in the forum.

Follow TRS On Instagram

Latest Album Photos

Hunters
20240409_190831.jpg
20240409_190818.jpg
20240409_180824.jpg
20240409_182648.jpg
20240409_181010.jpg
20240408_175026.jpg
99 Ranger
20200706_161414.jpg
20240207_155117.jpg
20240207_155111.jpg
20240207_154537 - Copy.jpg

TRS Events

25th Anniversary Sponsors

Check Out The TRS Store


Sponsored Ad


Sponsored Ad

Sponsored Ad


Amazon Deals

Top