Results 1 to 13 of 13

Thread: No power to fuel pump relay, why?

  1. #1
    Join Date
    Dec 2012
    Location
    Lincoln, NE
    Posts
    21

    No power to fuel pump relay, why?

    Have 91 SC has been running fine when some bolts holding pulley to harmonic balancer broke and others stripped out threads. Replaced Harmonic balancer and pulley, turns over but won't start. I assumed it had to do with the crank position sensor but when I checked for fire at the plugs I have spark. Noticed didn't hear fuel pump cycle when turning on key. Inertia sensor has continuity. Fuel pump relay hot wired and I have 40lbs of pressure. Spins over but doesn't try to start with 40lbs pressure. Apparently no juice to fuel pump relay and injectors? Checked high current fuses under hood, all have continuity and power to them. Any ideas on what to check next and how to check it would be much appreciated.

  2. #2
    Join Date
    Apr 2002
    Location
    Greenville, IN
    Posts
    4,220
    Quote Originally Posted by lfiers889 View Post
    Have 91 SC has been running fine when some bolts holding pulley to harmonic balancer broke and others stripped out threads. Replaced Harmonic balancer and pulley, turns over but won't start. I assumed it had to do with the crank position sensor but when I checked for fire at the plugs I have spark. Noticed didn't hear fuel pump cycle when turning on key. Inertia sensor has continuity. Fuel pump relay hot wired and I have 40lbs of pressure. Spins over but doesn't try to start with 40lbs pressure. Apparently no juice to fuel pump relay and injectors? Checked high current fuses under hood, all have continuity and power to them. Any ideas on what to check next and how to check it would be much appreciated.
    Do you still have a stock balancer or replacement?
    Matt Haub
    Shootouts: '09 SS 1st | '10 Mod1 2nd | '11 Bracket 3rd | '12 Bracket 1st | 2013 | '14 Bracket 3rd | 2015 | '16 Bracket 1st & Mod2 2nd | 2017 |
    Black '89 5spd - 281K miles, MPx, E85, Alky-Inj RWHP: ? RWTQ: ? Best 1/4mi:12.521, MPH:107.23mph
    35th Anniversary Auto 46k miles | Red '93 Auto 186k miles
    My Garage

  3. #3
    Join Date
    Dec 2007
    Location
    Salem, OR
    Posts
    6,293
    Is that 40psi fuel at the valve on the rail?

    Is the multi-wire ignition switch down on the side of the steering column original?

    Did you confirm the balancer is fully plunged?

    12+ volts at the battery?

    Upshift or check engine light on while cranking?

    Vacuum line at the FPR dry?

  4. #4
    Join Date
    Dec 2012
    Location
    Lincoln, NE
    Posts
    21

    Harmonic Balancer

    Quote Originally Posted by DrFishbone View Post
    Do you still have a stock balancer or replacement?
    The harmonic balancer is a used one with the pulley balanced to it. Same part number as original and inspected before installing, appeared to be exactly same.

  5. #5
    Join Date
    Dec 2012
    Location
    Lincoln, NE
    Posts
    21

    Answers to questions

    Quote Originally Posted by KMT View Post
    Is that 40psi fuel at the valve on the rail?

    Is the multi-wire ignition switch down on the side of the steering column original?

    Did you confirm the balancer is fully plunged?

    12+ volts at the battery?

    Upshift or check engine light on while cranking?

    Vacuum line at the FPR dry?
    The fuel line pressure is measured at the schraeder valve on the rail. The ignition switch is original. The balancer is torqued to 120 ft lbs and in line with the other pulleys. The battery is +12 volts. Upshift light and check engine light are not on when cranking. If FPR stands for Fuel Pump Relay there is no vacuum line in the trunk by the relay. Good questions, appreciate the help.

  6. #6
    Join Date
    Jul 2015
    Location
    Chicago
    Posts
    90
    FPR= fuel pressure regulator. Located on hen. Back of the fuel rail toward the drivers side of the motor. Kinda under the whiper assembly.

  7. #7
    Join Date
    Dec 2012
    Location
    Lincoln, NE
    Posts
    21

    The latest...

    Checked the timing just by cranking engine with timing light and it is at 10 degrees per spec. So conclude harmonic balancer is installed correctly. Monig on: Fuel pump relay in trunk has 4 wires; power (black/yellow), fuel pump (pink/black), coil power (white), and what I think should be coil ground? So when switch is on I have 12+ volts at power and coil power, nothing at fuel pump, and 10 volts at the coil ground. Obviously the relay coil wont actuate with no ground, but when I turn the switch off I get a short surge of about 10 lbs from the fuel pump. I am assuming this is due to the coil ground no longer having 10 volts and actually working as a ground? My Chilton refers to this coil ground wire as number 22 on the 60 pin and it is called FP for Fuel Pump. It is connected to the self test connector as well. Which speaking of I can't seem to find so I can run the self test and try to get some codes. I have looked by the AC drier near the firewall on the passenger side, near the master brake cylinder reservoir on the river side, and under the dash on both sides. Where the H E double toothpicks did the geniuses at Ford hide it? Other question I have is what would cause voltage to be in ground wire for fuel pump relay?

  8. #8
    Join Date
    Jul 2005
    Posts
    382

  9. #9
    Join Date
    Jul 2004
    Location
    Hamilton NJ
    Posts
    1,963
    A lot of times the fuel pump harness cracks and breaks from being brittle above the gas tank, had that happen before...Also had the pink 30amp under the hood blown for the EEC and I wasn't getting fuel pump power.
    Tom Downs-member#2752
    MPX'd 90 SC Auto~bought Feb. 2012
    http://www.sccoa.com/forums/garage_v...vehicle&id=424

  10. #10
    Join Date
    Dec 2012
    Location
    Lincoln, NE
    Posts
    21

    Bad computer>

    I tried to run the codes but check engine light stays on when I hook up. Book says that indicates short or open circuit. Fuel pump runs when grounding self test connector for pump indicating circuit is good but not receiving signal from computer when switch is turned on, supposed to run a few seconds to build up pressure to start. Based on that info I want to buy a used computer that was working but replaced for performance enhancement reasons. Anybody got one?

  11. #11
    Join Date
    Dec 2012
    Location
    Lincoln, NE
    Posts
    21

    Bad Computer?

    Since fuel pump works when grounding self test terminal for pump and since tried to read codes but check engine light stays on indicating hard fault (open or short circuit) I believe I need a computer. Anybody got a good used one? lonn1950@gmail.com

  12. #12
    Join Date
    Jul 2005
    Posts
    382
    Good evening


    I would check the IRCM before replacing the EEC. If you look at the attachment the IRCM has three relays one of which powers the EEC. Check the connector for corrosion/damaged pins. Below is 2 quick test(s) I do.


    (1) Have another person turn the Key On Engine Off (KOEO) while I am next to IRCM. Listen carefully for the relay to energize with a "click". Do this few times. If no click suspect the IRCM and or wiring.


    (2) Remove the air box for better access to the IRCM. Repeat step (1) KOEO. Tap on the IRCM case with an screwdriver (handle end) or long 3/8 drive extension to "jar" the relay to life. Again if no click is heard suspect the IRCM and or wiring.


    Attachment. http://www.sccoa.com/forums/showthre...-schematic-pdf



    Good Luck.

  13. #13
    Join Date
    Dec 2012
    Location
    Lincoln, NE
    Posts
    21

    Looking for used computer

    I may be wrong here but I read if I have spark the ICRM EEC relay is working. I have spark. What I don't have is fuel pump pressure at key on, should run a few seconds. I checked the fuel pump circuit by grounding the self test plug and fuel pump runs. Still think computer has problem not grounding pump for a few seconds. Does anyone have a good computer part # F1WF-12A650-AA, that is the one for the manual tranny. My email is lonn1950@gmail.com Thanks so much for the help.

Similar Threads

  1. Have to jump fuel pump relay for engine to run
    By Mike Puckett in forum Technical Forum
    Replies: 6
    Last Post: 04-18-2009, 05:16 PM
  2. No electricity to fuel pump
    By metalman in forum Technical Forum
    Replies: 12
    Last Post: 07-11-2004, 08:22 AM
  3. No power to ac compressor
    By Jake in forum Technical Forum
    Replies: 7
    Last Post: 05-25-2003, 07:57 PM
  4. Where is the fuel pump relay on my 89 SC?
    By phils89sc in forum Technical Forum
    Replies: 1
    Last Post: 04-18-2003, 11:33 AM
  5. Fuel pump relay
    By xracer9x in forum Technical Forum
    Replies: 1
    Last Post: 01-04-2003, 02:24 PM

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •