Fuel pump only runs one second

Tiny
J W PRUITT 56
  • MEMBER
  • 1999 DODGE DAKOTA
  • 3.9L
  • 6 CYL
  • 4WD
  • MANUAL
  • 180,000 MILES
Truck was running and cut off, after setting a few minutes would start run a few seconds cut off. 52 lbs fuel pressure,
Now won’t start fuel pump starts cuts off immediately, will run if I pour gas into throttle body. I replaced fuel pump, crankshaft position sensor, camshaft sensor, relays fuses, what could be problem, what am I missing? Could it be PCM?
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Monday, October 28th, 2019 AT 5:09 AM

19 Replies

Tiny
ASEMASTER6371
  • EXPERT
Good morning,

The relay for the pump is something you need to check.

The control side is fed by a fuse listed in the diagram I attached. The ground is the PCM. That is what controls the operation of the pump.

The load side has power from a fuse and then directly to the pump.

You need to start by verifying 2 powers to the relay.

Roy
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Monday, October 28th, 2019 AT 5:32 AM
Tiny
J W PRUITT 56
  • MEMBER
I am only getting power on one point on fuel pump relay and ASD relay. Have checked all fuses, replaced relays, stripped harness of protective covering coming out of power distribution box to check splice. I ve read can be a problem, it looked fine. Been cleaning grounds. Pump still not working. Any help is greatly appreciated!
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Tuesday, October 29th, 2019 AT 7:42 AM
Tiny
J W PRUITT 56
  • MEMBER
I am only getting power on one point on fuel pump relay and ASD relay, have checked all fuses, replaced relays, stripped harness of protective covering coming out of power distribution box to check splice I ve read can be a problem, it looked fine, been cleaning grounds, pump still not working. Any help is greatly appreciated!
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Tuesday, October 29th, 2019 AT 7:42 AM
Tiny
ASEMASTER6371
  • EXPERT
Okay, there will be one leg hot with the key on. That is terminal 30 for the load side to the
pump.

https://www.2carpros.com/articles/how-to-check-an-electrical-relay-and-wiring-control-circuit

The control side comes directly from the PCM and is timed for 2 seconds and shuts off.

You need to recheck for power in the first 2 seconds with the key on. After 2 seconds, the power will disappear until the engine is cranking.

Roy
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Tuesday, October 29th, 2019 AT 8:01 AM
Tiny
J W PRUITT 56
  • MEMBER
Got a friend to help me turn on switch while I test.I have power on 1 leg with switch off. With switch on I have 2 legs hot. Doesn t cut off after 2 seconds. Fuel pump still starts and immediately stops. I have never had these problems before. I ve been working on my vehicles and friends and family and neighbors for nearly 50 years.
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Thursday, October 31st, 2019 AT 10:06 AM
Tiny
ASEMASTER6371
  • EXPERT
Okay, in the relay, I need you to jump the 2 wires I circled. See if the pump runs.

Roy
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Thursday, October 31st, 2019 AT 12:37 PM
Tiny
J W PRUITT 56
  • MEMBER
The pump ran for about 5 seconds can't get it to run again. Sorry for waiting a few days, I was out of town and just got home today.
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Monday, November 4th, 2019 AT 10:09 AM
Tiny
J W PRUITT 56
  • MEMBER
After waiting a few minutes I got it to run a couple of seconds and cut back off.
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Monday, November 4th, 2019 AT 10:23 AM
Tiny
ASEMASTER6371
  • EXPERT
When you jumped the relay, did it stay running or cut off?

You need to jump the relay again and check the voltage at the fuel pump connector. The red/white wire needs to have battery voltage.

Roy
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Monday, November 4th, 2019 AT 12:06 PM
Tiny
J W PRUITT 56
  • MEMBER
When I jumped the relay it only ran for a couple of seconds. I will recheck for power tomorrow. Thank you
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Monday, November 4th, 2019 AT 5:03 PM
Tiny
ASEMASTER6371
  • EXPERT
Okay,

Keep me updated.

Roy
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Monday, November 4th, 2019 AT 5:07 PM
Tiny
J W PRUITT 56
  • MEMBER
I have power on the green and black wire when I jump to red and white it has no power and I lose power on the green and black. When I remove jumper wire I again have power on green and black wire.
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Tuesday, November 5th, 2019 AT 9:28 AM
Tiny
ASEMASTER6371
  • EXPERT
The green/black is grounded. Remove the connector from the fuel pump itself and retest and see if you have power on that wire.

You may have a bad pump.

Roy
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Tuesday, November 5th, 2019 AT 11:02 AM
Tiny
J W PRUITT 56
  • MEMBER
I have power on green wire going into gas tank, does this indicate I have a bad fuel pump. I replaced pump a little over a year ago, but I know they can fail.
Thank you
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Tuesday, November 5th, 2019 AT 12:33 PM
Tiny
ASEMASTER6371
  • EXPERT
It must be the green/black. The other wire is for the gauge sender unit.

Roy
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Tuesday, November 5th, 2019 AT 1:03 PM
Tiny
J W PRUITT 56
  • MEMBER
Okay, I am getting power to the pump when I run a jumper between contacts on the fuel pump relay. So does that mean my pump is bad?
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Tuesday, November 5th, 2019 AT 4:27 PM
Tiny
ASEMASTER6371
  • EXPERT
If the green/black wire is powered, then yes, you need a pump.

Roy

REMOVAL

WARNING: THE FUEL SYSTEM IS UNDER A CONSTANT PRESSURE (EVEN WITH ENGINE OFF). BEFORE SERVICING FUEL PUMP MODULE, FUEL SYSTEM PRESSURE MUST BE RELEASED.

1. Drain fuel tank and remove tank. Refer to Fuel Tank Removal/installation.
2. Thoroughly wash and clean area around pump module to prevent contaminants from entering tank.

Top View Of Fuel Pump Module
imageOpen In New TabZoom/Print

Locknut Removal/Installation - Typical
imageOpen In New TabZoom/Print

3. The fuel pump module locknut is threaded onto fuel tank. Install Special Tool 6856 to fuel pump module locknut and remove locknut.
4. Remove module from fuel tank.

INSTALLATION

CAUTION: Whenever fuel pump module is serviced, the module gasket must be replaced.

1. Using a new gasket, position fuel pump module into opening in fuel tank. Be sure rubber gasket remains in place. Rotate module assembly until module alignment arrow is at 7 o'clock position. This step must be followed to prevent float/float rod from contacting sides of fuel tank.
2. Position locknut over top of fuel pump module. Tighten finger tight.
3. Carefully rotate fuel filter/fuel pressure regulator until pointed towards drivers side of vehicle.
4. Install Special Tool 6856 to locknut.
5. Tighten locknut to 54 N-m (40 ft. Lbs.) Torque. While tightening locknut, be sure module has not rotated.
6. Install fuel tank. Refer to Fuel Tank Installation.
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Wednesday, November 6th, 2019 AT 1:51 AM
Tiny
J W PRUITT 56
  • MEMBER
Thank you for help answering my questions and helping me diagnose my problem!
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Wednesday, November 6th, 2019 AT 7:48 AM
Tiny
ASEMASTER6371
  • EXPERT
You are welcome.

Always glad to help.

Roy
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Wednesday, November 6th, 2019 AT 8:06 AM

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