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Crank no start issue?

Tiny
CISCODLR
  • MEMBER
  • 2002 DODGE RAM
  • 4.7L
  • V8
  • 2WD
  • AUTOMATIC
  • 180,000 MILES
Thanks for any help first of all, 2the truck listed above is 1500. Crank but no start, no reading on fuel gauge. Started one morning for about 2 seconds then shut off.
I have replaced fuel pump, TIPM, Crankshaft Position Sensor, Ignition Switch, fuses and relays, no luck. I have no power at fuel pump connecting. I have bypassed the fuel pump relay and then I have power to fuel pump connection (fuel pump turns on), tried to start truck with bypass wire on and no start. Checked pin voltage at fuel pump relay, pin30 constant 12V, pin86 good ground (when ignition is on). Pin 85 no voltage until key is on (signal from ECM?) Pin87 signal wire to fuel pump. I raised the relay slightly to probe pins with relay on, still have constant 12v on pin 30, 12v on signal wire from ECM, but no voltage to pin 87 to fuel pump.
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Sunday, June 25th, 2023 AT 1:46 PM

16 Replies

Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,689 POSTS
Hi,

The primary side of the relay, pin 85, should have power with the key in the run or start position. If it does, check to see if there is a ground path being provided via pin 86.

If there is no power to pin 85, check the PTC fuse in the under-hood power distribution box. If there is power and no ground, we need to check if there is a wiring issue or if the PCM is causing issues.

I attached a couple of pics below showing the relay and power supply so that you have a reference.

What I am finding interesting is the idea that you jumped the relay and the pump turned on, but the truck didn't start. When you first turn the key on, do you hear the pump prime? I ask because if there is no ignition (engine start) it will shut down the pump.

Let me know.

Joe

See pics below.
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Sunday, June 25th, 2023 AT 10:26 PM
Tiny
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Thanks for responding, Pin 85 does have power(12v) with key in run/start position. Pin86 is a good ground, and no, the pump does not prime when I turn the key on.
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Monday, June 26th, 2023 AT 5:25 AM
Tiny
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Forgot to mention pin 86 (ground) only comes on when key is in the run/start position, which may be how it's designed, but I'm not sure.
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Monday, June 26th, 2023 AT 5:42 AM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,689 POSTS
Hi,

Are you sure the relay is good? It sounds like it is working normally. If the primary circuit is complete (pins 85 and 86), the secondary side should close and allow power to reach the pump. If you jump the relay, the pump runs, so something is preventing power from going through the relay.

Take a look at this link and let me know if it helps:

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

Do you have spark at the plugs? Have you checked the ASD relay? See pic below.

Let me know.

Joe

See pic below.
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Monday, June 26th, 2023 AT 9:13 PM
Tiny
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Thank you, Joe, I haven't responded been super busy, but truck still not working, I did check spark at coil over plug, and no spark. Replaced ASD, and ASD fuse is good.
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Sunday, July 2nd, 2023 AT 3:45 PM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,689 POSTS
Hi,

Okay, I need you to check if the coils are getting power. I attached a pic below of the ignition coils and fuel injectors. Note that each injector and each coil have two wires each and one of the two is dark green with an orange tracer.

Check to see if that wire on the injector has power with the key in the run position.

Let me know what you find.

Take care,

Joe
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Sunday, July 2nd, 2023 AT 11:05 PM
Tiny
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  • MEMBER
  • 11 POSTS
Pic Joe?
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Monday, July 3rd, 2023 AT 4:39 AM
Tiny
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  • MEMBER
  • 11 POSTS
Hello Joe, I checked for power at the fuel injector (dark green wire with orange tracer) and found no power with the key on the run position.
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Monday, July 3rd, 2023 AT 5:53 AM
Tiny
CISCODLR
  • MEMBER
  • 11 POSTS
Joe,

No signal at fuel injectors (Noid tester) Good ASD Relay/fuse, 2 hots at ASD relay, good ground, jumped a hot to pin 87 still no power to pump. I have already replaced the Crank sensor also, any help is appreciated.
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Monday, July 3rd, 2023 AT 10:57 AM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,689 POSTS
Hi,

If the ASD relay is good and has power, but the injectors/coils don't have power, there has to be an open between the two. See pics 1 and 2.

There is a splice in the wiring at the left rear of the engine compartment. (See pic 3) Since you have no power to the coils or the injectors, the splice could be the cause.

See if you can locate the splice.

Take care,

Joe

See pics below. I highlighted the wiring in question.
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Monday, July 3rd, 2023 AT 10:07 PM
Tiny
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Thanks Joe, will check in the morning.
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Monday, July 3rd, 2023 AT 10:14 PM
Tiny
CISCODLR
  • MEMBER
  • 11 POSTS
Joe, checked the wire splice and found nothing unusual, I did check continuity with my meter from pin 87 at the relay to the green/orange wire to both the fuel injectors and the coils, and did have continuity. Thanks Joe
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Tuesday, July 4th, 2023 AT 3:44 PM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,689 POSTS
Hi,

If the relay is sending power and the power wire has continuity, the components should have power. Do you have power at the splice?

Joe
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Tuesday, July 4th, 2023 AT 10:07 PM
Tiny
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  • MEMBER
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Will check, and get back to you. Thanks
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Wednesday, July 5th, 2023 AT 5:43 AM
Tiny
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Thank you Joe for your help, I replaced the ECM and that did it.
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Friday, September 22nd, 2023 AT 1:53 PM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
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Hi,

First, thank you for the update. If I helped at all, you are very welcome. I'm glad to know you got things going again.

Regardless, take care of yourself, and feel free to come back anytime in the future.

Joe
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Friday, September 22nd, 2023 AT 2:43 PM

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