No power to fuel pump

Tiny
CHRISTA G
  • MEMBER
  • 1994 DODGE SHADOW
I have had the fuel pump replaced and now there is no power going to it. Is there something wrong with the wiring? Also, where is the relay located? Please need help ASAP. Thank you. Please help.
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Sunday, November 20th, 2011 AT 2:41 AM

9 Replies

Tiny
CARADIODOC
  • EXPERT
What are the symptoms? Have you checked for spark? Also, which engine do you have, the 2.5 four cylinder or the 3.0L V-6? I could be the relay but we need to check first I do not want you to buy parts you do not need.

There is a fuel pump and auto shut down relay that can cause the problem as well. Here is a guide to help you test the relays:

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

Check out the diagram (below).

Please let us know what you find. We are interested to see what it is.

Cheers
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Sunday, November 20th, 2011 AT 3:38 AM
Tiny
CHRISTA G
  • MEMBER
It is a 3.0L V-6. I took the gas tank off to fix the leak. I got busy so it sat for three years. I put the tank back on, then found no power in the wires going to the fuel pump. The car worked just fine before I took the tank off.
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Sunday, November 20th, 2011 AT 3:06 PM
Tiny
CARADIODOC
  • EXPERT
I have typed this reply so many times that sometimes I leave important details out so be sure to ask if something does not make sense. The ignition coil, injectors, alternator field, and fuel pump or fuel pump relay are powered through the automatic shutdown (ASD) relay. That is why you have to check for spark. Do not get stuck on the bad fuel pump.

If you do have spark, then we will work on the fuel pump circuit but first it is important to understand how that one works. With the ignition switch in the "run" position you should not have voltage to the pump. The engine computer turns on the ASD relay for only one second after you turn on the ignition switch, (you might hear the pump hum), then it turns it back off. The computer will turn the relay on again during engine rotation, (cranking or running). It know there is rotation by the pulses it receives from the optical pickup inside the distributor. That assembly has a very low failure rate. What is more likely is the timing belt is broken. You can verify that by observing if the distributor rotor turns during engine cranking. Of course if you do have spark, the timing belt is okay and the ASD relay is turning on. To check for voltage at the fuel pump connector you will have to measure while a helper is cranking the engine. If you have to work on this problem alone, I can explain how to bypass the ASD relay so you can take your time taking measurements.
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Sunday, November 20th, 2011 AT 8:15 PM
Tiny
CHRISTA G
  • MEMBER
Oops, last response was an accident. Thank you! That helps out a lot. I also messed up on the make and model. It is a Plymouth Duster 3.0L V-6. I hope there is not much of a difference.
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Monday, November 21st, 2011 AT 1:33 AM
Tiny
CARADIODOC
  • EXPERT
Nope. The Duster was a model of the Plymouth Sundance, and twin to the Dodge Shadow. The interior trim is the biggest difference.

The 3.0L engine is real desirable and not terribly common in that car. In case you are not already aware of it, you have a really tough little car. My friend who used to own a body shop had one. His girlfriend pulled into traffic and got broadsided in the driver's door by a large GM car going thirty five mph. The interior door panel never got touched thanks to a steel beam inside the door. Her only injury was from hitting her head on the door. One used door and a little body work and the car was back on the road. The Oldsmoblile Cutlass had more dollars worth of damage than the Shadow.

I used a lot of Shadows to create learning exercises for my students. We had six of them, some donated by Chrysler. They were easy to work on and diagnose. If I could find a nice rust-free one, I would turn that into my daily driver and save my 1988 Grand Caravan. The Neon replaced the Shadow/Sundance in 1995. No self-respecting mechanic would want to own one of those.
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Monday, November 21st, 2011 AT 3:00 AM
Tiny
CHRISTA G
  • MEMBER
That is great to know that it is a trusty car. :) I checked for spark and there is spark. Is there any fuse for the fuel pump? I did not find one under the dashboard. What should I check next?
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Saturday, December 3rd, 2011 AT 10:20 PM
Tiny
CARADIODOC
  • EXPERT
Dandy. Having spark rules out all of the common stuff and just leaves the fuel pump circuit. I can only find a service manual for a 1993 model, and I think the fuse box for a 1994 is different. Do you have a fuse box under the hood, driver's side, or do you have six relays bolted to the body, three on the left inner fender and three in front of the left strut tower? I am trying to point out which one is for the fuel pump, woops, I just found my 1994 manual and it looks like you have individual relays yet like on a1993 model. If that is right, the fuel pump relay is on the strut tower, closest to the center of the car, of the three.

There are a couple of ways to approach this. You can use a test light back at the tank to test for voltage. As I recall, the connectors are on the right side where you can reach them without lowering the tank. Unplug the fuel pump connector and test on the dark green/black wire. It is important to understand there will only be voltage there for one second after turning on the ignition switch so you are either going to need a helper to turn the switch on or you are going to have to prop the test light up so you can see it from inside the car. You can use a digital voltmeter too but often they do not respond fast enough. Also, voltmeters draw almost no current to do their testing. Test lights draw plenty of current to show up a high-resistance break in the circuit that can prevent the pump from running but be enough for a voltmeter to give an acceptable reading. The test light, in this case, is more accurate.

If you see voltage for that first one second, the relay and wiring to the tank are okay. With the connector plugged in, you should be hearing the hum of the pump for one second when you turn on the ignition switch.

As an alternative, you can bypass the fuel pump relay with a stretched out paper clip. You will not even need to turn on the ignition switch for any of the tests. Unplug the relay's connector and jump between the dark green/black wire and the red/white wire. They will be two of the three fatter wires. Doing that will send voltage to the fuel pump just as though the engine was running. If the pump does not run, you can take voltage readings now anywhere in the circuit.

If you find voltage at the pump's connector, either the pump is stuck or the terminal in the connector is spread or corroded and not making a good connection. We have to consider a bad ground wire too. It is fairly common for the pump to not start running due to worn brushes in the motor. Banging on the bottom of the tank will often get them going, and that works even better if you do it while voltage is applied. Once the pump is running, Chrysler pumps almost never quit and let you sit on the side of the highway. They will fail to start up but not quit until the engine is shut off. GM pumps are known to suddenly quit and leave you stranded on the side of the road in a puddle of tears.

Holler back after you have made these tests.
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Saturday, December 3rd, 2011 AT 11:31 PM
Tiny
CHRISTA G
  • MEMBER
Good call on the ASD relay. My dad replaced it and now the car is running ya! I love this site thanks for all of your help.
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Tuesday, December 20th, 2011 AT 6:26 PM
Tiny
CARADIODOC
  • EXPERT
Glad you could get it fixed, that kind of problem can be tough. Please use 2CarPros anytime we are here to help.

Cheers
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Tuesday, December 20th, 2011 AT 10:01 PM

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