Truck will not run

GANDERSON32

MEMBER
1992 DODGE DAKOTA
5.2L
V8
4WD
AUTOMATIC
200,000 MILES

The Truck just coughed and shut off. So, believing that the fuel pump had failed, I bought a new one and installed it. ( It would start and run when gas was poured into the throttle body). However, it does not run now. I have changed computers, new fuel pump. I am at a loss, I think it might be in the wiring, but not sure. Can you help?

9 Replies

CARADIODOC

MECHANIC
33,760 POSTS

Double check that you have spark, then check the fuel pressure. You can have a loss of spark. It sounds like you have a loss of fuel pressure or injector pulses. By far the majority of crank/no-starts is caused by a loss of spark and fuel.

Also, listen for the hum of the fuel pump for one second when you turn on the ignition switch. If you hear that, the pump and its wiring are okay. Chrysler fuel pumps rarely fail while they are running. They typically fail to start up.

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Saturday, February 24th, 2018 AT 6:35 PM

GANDERSON32

MEMBER
9 POSTS

I have spark, but no fuel, as the fuel pump will not run. I have the unit unplugged right now, and the only wire that lights up with my tester, is the "low fuel" light, even the tank is full, but only registers empty on the gauge.

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Sunday, February 25th, 2018 AT 8:33 AM

CARADIODOC

MECHANIC
33,760 POSTS

Are you aware the fuel pump only runs for one second when you turn on the ignition switch? A lot of people mistakenly think they can just turn the ignition switch to "run", then expect to find 12 volts at the fuel pump's connector.

Do you hear the fuel pump run for that one second? If you do, you're done in that circuit. It's working properly. If you don't or can't hear if the pump runs for that one second, find the fuel pump relay and bypass it. That will let you perform tests in the circuit at your leisure without even needing to have the ignition switch on. Your relay is plugged into the under-hood fuse box. Remove it, then use a jumper wire or stretched-out paper clip to connect terminals 30 and 87 together in the socket.

Now you can listen under the tank if the pump is running. If it's not running, check for 12 volts on the dark green / black wire in the pump's connector. You can use a digital voltmeter, but for this type of problem, a test light will be more accurate. Let me know what you find.

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Tuesday, February 27th, 2018 AT 11:23 AM

GANDERSON32

MEMBER
9 POSTS

Whenever I use the "stretched out paper clip" I can hear a clicking on noise somewhere on the left side of the engine, however, I cannot hear the pump run. I will get to the wiring sometime today. I hope then I can find the problem. Thanks so much

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Wednesday, February 28th, 2018 AT 9:54 AM

CARADIODOC

MECHANIC
33,760 POSTS

Sometimes you can hear the hiss at the fuel pressure regulator when you bypass the fuel pump relay. That is from the fuel flowing through the spring-loaded valve in the regulator. It's on the fuel rail that runs between the injectors. That will tell you the pump is running. Chrysler fuel pumps are built to very tight clearances which makes them relatively quiet and hard to hear.