1999 Ford F-150 low voltage at fuel pump

Tiny
JADAMS6831
  • MEMBER
  • 1999 FORD F-150
  • V8
  • 4WD
  • AUTOMATIC
  • 130,000 MILES
Changed bad alternator now fuel pump wont run. Checking 7.3 volts at fuel pump connection. Checking 7.3 volts at the emergency shut off switch. Battery is fully charged. Replaced fuel pump also. Changed relay also. Where is fuel pressure regulator located, could it be the problem
Do you
have the same problem?
Yes
No
Sunday, May 23rd, 2010 AT 5:24 AM

9 Replies

Tiny
KHLOW2008
  • EXPERT
Hi jadams6831,

Thank you for the donation.

No, it is not a problem with the fuel pressure regulator if the fuel pump is not running.

The voltage should be battery voltage at the fuel pump and since you are only getting 7.3 volts, something is wrong somewhere.

Is your engine 4.0, 4.6 or 5.4 L?
Did you test the voltage at the fuel pump relay?
Was this
answer
helpful?
Yes
No
Monday, May 24th, 2010 AT 10:03 AM
Tiny
JADAMS6831
  • MEMBER
Hadnt gotten that far yet. Did swap out relay though, it didnt change anything. Cant figure out why changing alt caused this or coisadence.
Was this
answer
helpful?
Yes
No
Monday, May 24th, 2010 AT 4:23 PM
Tiny
KHLOW2008
  • EXPERT
I need to know the engine specs to get the correct wiring diagrams
Was this
answer
helpful?
Yes
No
Monday, May 24th, 2010 AT 4:27 PM
Tiny
JADAMS6831
  • MEMBER
Sorry. Its a 5.4l extended cab xlt 150
Was this
answer
helpful?
Yes
No
Monday, May 24th, 2010 AT 7:28 PM
Tiny
KHLOW2008
  • EXPERT
The fuel pump relay gets it power from Fuse # 10 ( 20 A) ( Light Blue/Orange wire). Check if you have 12 volts to the fuel pump relay via this wire ( terminal # 30 of relay ).

Remove fuel pump relay and apply battery voltage to terminal # 87 of fuel pump relay and check if the fuel pump works.

Under right side of dash there is an inertia fuel shut off switch. Check for continuity between th eDark Green/Yellow and Pink/Black terminals.
Was this
answer
helpful?
Yes
No
Tuesday, May 25th, 2010 AT 7:42 AM
Tiny
JADAMS6831
  • MEMBER
Thanks for your assistance I think I can get it from here. Jadams6831
Was this
answer
helpful?
Yes
No
Tuesday, May 25th, 2010 AT 6:55 PM
Tiny
KHLOW2008
  • EXPERT
You're welcome and if you have anything more, just post reply and I will get back to you once I am online.

Thank you for using 2carpros and have a nice day.
Was this
answer
helpful?
Yes
No
Wednesday, May 26th, 2010 AT 8:00 AM
Tiny
JADAMS6831
  • MEMBER
We found a bad tang on fuel pump fuse. Of coarse fuse checked good but thats what happens when you assume. Thanks for your help
Was this
answer
helpful?
Yes
No
Wednesday, May 26th, 2010 AT 7:47 PM
Tiny
KHLOW2008
  • EXPERT
Glad you have fixed the problem.

Have a nice day.
Was this
answer
helpful?
Yes
No
Thursday, May 27th, 2010 AT 9:24 AM

Please login or register to post a reply.

Recommended Guides