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How to test the Fuel Pump?

Tiny
KEVINKLEIN
  • MEMBER
  • 1999 LINCOLN CONTINENTAL
  • 103,000 MILES
I was wondering how to test the Fuel Pump Driver Module. I tested using a volt meter using a mounting bolt for a ground. I had 12v on the White wire and 9v on the Blk/Yel wire for about a 1-2 seconds when the key was turned on and then continuously while cranking.
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Sunday, December 16th, 2012 AT 12:53 AM

13 Replies

Tiny
FIXITMR
  • MECHANIC
  • 9,990 POSTS
I take it car is not starting, pump is not running? You can remove relay and jumper 12v to pump wire to see if it runs.
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Sunday, December 16th, 2012 AT 1:08 AM
Tiny
KEVINKLEIN
  • MEMBER
  • 5 POSTS
Is there a relay between the Fuel pump driver module in the trunk behind the rear seat and the fuel pump?
I can pull the plug from the FPDM and jump from there if there is not a relay between the FPDM and the pump unless there is a better place to jump 12v from.
Can you tell me which wire to put 12v to?
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Sunday, December 16th, 2012 AT 2:36 AM
Tiny
ASEMASTER6371
  • MECHANIC
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Did you get the wiring diagram I sent you?

You need to test the wire to the pump first to verify voltage to the pump with key on for 2 seconds. If there is no voltage, go back to the inertia switch to see if there is voltage there. If not, go back to the relay to see if the relay is sending the signal.

Roy
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Sunday, December 16th, 2012 AT 2:37 AM
Tiny
FIXITMR
  • MECHANIC
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Actually I misread and thought you were talking about relay when you said module. I was giving general advice not vehicle specific. Your car does not have a relay for pump.
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Sunday, December 16th, 2012 AT 3:25 AM
Tiny
KEVINKLEIN
  • MEMBER
  • 5 POSTS
Sorry I did not receive wiring diagram.
I tested the inertia switch and have power.
I tested wiring at the module using a volt meter using a mounting bolt for a ground. I have 12v on the White wire and 9v on the Blk/Yel wire for about a 1-2 seconds when the key was turned on and then continuosly while cranking.
I do not know if these are the correct wires or not.
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Sunday, December 16th, 2012 AT 4:29 AM
Tiny
ASEMASTER6371
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Should be 12 volts to the pump.

If that is the case, I would replace both the module and the fuel pump as the pump may have caused the module to fail from excessive draw.

Roy
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Sunday, December 16th, 2012 AT 4:37 AM
Tiny
KEVINKLEIN
  • MEMBER
  • 5 POSTS
I saw a wiring diagram on this site
https://www.2carpros.com/questions/1998-lincoln-continental-98-cotinental-fuel-pump-wiring-diagram
for a 1998 continental and it shows that the wht/red wire and the blk/yel wire are for the fuel pump. Should the wht/red wire have power. I tested it and there is no power to this wire only the blk/yel has power and the solid white wire has power which I assume is the power supply to the module.
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Sunday, December 16th, 2012 AT 5:17 AM
Tiny
ASEMASTER6371
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White is power to the module. White/red is the return from the pump or the module grounds the pump to turn it on and off. If there is 0 volts, it is grounded. Any voltage means it is not grounded. Thus indicating an issue.

Roy
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Sunday, December 16th, 2012 AT 5:25 AM
Tiny
KEVINKLEIN
  • MEMBER
  • 5 POSTS
So it looks like I definitely need to replace the fuel pump.
Is that correct?
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Sunday, December 16th, 2012 AT 5:34 AM
Tiny
FIXITMR
  • MECHANIC
  • 9,990 POSTS
I'd test it to make sure it's the problem. And I read that thread and it seems the pump or line pressure is adjustable by the module? Says only proper diagnosis is an expensive scan tool. But if pump dont respond to direct voltage you apply as test then yup. You saved some money?
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Sunday, December 16th, 2012 AT 6:36 AM
Tiny
ASEMASTER6371
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I would agree

Roy
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Sunday, December 16th, 2012 AT 6:36 AM
Tiny
RFELK
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Hope this helps. Been working on son-in-law’s 98 Continental. It would crank, but not start. Fuel pump would not run. Good spark. Injectors were not operating. Good 12 volts to injectors, but no ground via PCM. Connected 12 volts directly to fuel pump and had 70psi at fuel rail, so good fuel pump. Changed cam position sensor as part of trouble-shooting, no change to problem. Read about same issue due to a bad coded key. Had son-in-law bring me his primary key and car started on first turn of key. The symptoms with the bad key was the security light on dash would flash rapidly when key was turn to ON position. With the good key in the ON position, the security light turned on solid and then shut off. Everything else was exactly the same with bad key. Good luck in solving your car issues!
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Saturday, February 18th, 2017 AT 9:50 PM
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 48,363 POSTS
Hey,

Great addition to this thread! Please feel free to help out on the site whenever it can add information that will help people.

Best, Ken
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Tuesday, February 21st, 2017 AT 1:39 PM

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