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Engine not running

Tiny
DAVIDGORDY
  • MEMBER
  • 1996 DODGE RAM
  • 5.9L
  • V8
  • 2WD
  • AUTOMATIC
  • 215,000 MILES
I have a fuel pump shutoff and electrical problem, I have replaced five fuel pumps to no avail. Fuel pressure at rail is 49 PSI, yet when key is turned on fuel pump runs and does not shut off at prescribed pressure of 49-50 PSI. If I cycle the key say 25 to 50 times giving a six second delay between cycles eventually the fuel pump will stop after the key is energized and the truck will start and run fine. But, after it is shut off and cools the cycle starts all over. Another symptom is that while the truck is in a no start condition I get a Data Link Error on the code reader (Autel). But as soon as the problem clears, Data Link is restored and no codes. I have replaced five pumps, purge valve, vapor canister which was bad, all eight injectors and fuses.
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Saturday, September 22nd, 2018 AT 10:11 AM

17 Replies

Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 48,323 POSTS
Two things come to mind which are the fuel pump relay and auto shutdown relay. I would remove them to check for heat damage. Also here is a guide that can help you test them and the location of the relays also I have included the engine wiring diagrams so you can see how the system works:

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

Check out the diagrams (below). Please let us know what happens.

Cheers, Ken
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Monday, September 24th, 2018 AT 12:46 PM
Tiny
DAVIDGORDY
  • MEMBER
  • 9 POSTS
Already Replaced both. This is the fifth fuel pump and regulator in the truck now.
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Monday, September 24th, 2018 AT 2:05 PM
Tiny
KEN L
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  • 48,323 POSTS
Both relays? If so please bypass the fuel pump relay (hot wire) to see if the truck starts and runs okay. Connect terminals 30 and 87.
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Tuesday, September 25th, 2018 AT 9:30 AM
Tiny
DAVIDGORDY
  • MEMBER
  • 9 POSTS
Bypassed the fuel relay 87 to 30 and it just turns the pump on as if the relay was there and the key was on. Still not turning on coil and injectors.
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Wednesday, September 26th, 2018 AT 12:22 PM
Tiny
KEN L
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  • 48,323 POSTS
Can you do the same with the ASD relay? It sounds like the PCM maybe bad. Lets use this guide and the wiring diagrams from above to check the wiring.

https://www.2carpros.com/articles/how-to-check-wiring

If everything checks out I would get a used PCM and replace it. Here is the location and pin out for the computer

Check out the diagrams (below). Please let us know what happens.
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Thursday, September 27th, 2018 AT 10:07 AM
Tiny
DAVIDGORDY
  • MEMBER
  • 9 POSTS
I have done both.
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Thursday, September 27th, 2018 AT 4:30 PM
Tiny
KEN L
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The data error code is making me think the PCM is bad. If you bypass the fuel pump relay does the fuel pressure stay good and not fall off?
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Friday, September 28th, 2018 AT 11:51 AM
Tiny
DAVIDGORDY
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  • 9 POSTS
Stays at 49-50 PSI.
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Friday, September 28th, 2018 AT 11:54 AM
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 48,323 POSTS
Does it run okay with the bypass? Can you please shoot a quick video with your phone so we can see what is going on? That would be great. You can upload it here with your response.
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Friday, September 28th, 2018 AT 12:02 PM
Tiny
DAVIDGORDY
  • MEMBER
  • 9 POSTS
It does not start with any bypass. So, no.
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Friday, September 28th, 2018 AT 12:03 PM
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
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Will it run will starting fluid? Here is a guide that can help us, does it have spark?

https://www.2carpros.com/articles/car-cranks-but-wont-start

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Saturday, September 29th, 2018 AT 11:15 AM
Tiny
DAVIDGORDY
  • MEMBER
  • 9 POSTS
No, it does not have spark.
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Saturday, September 29th, 2018 AT 11:16 AM
Tiny
KEN L
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Yep the link error is telling us the computer is having a problem if you have check the wiring I would say the PCM has gone out. I would try a used one and plug it in to see what happens.
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Saturday, September 29th, 2018 AT 11:41 AM
Tiny
DAVIDGORDY
  • MEMBER
  • 9 POSTS
Just ordered one.
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Saturday, September 29th, 2018 AT 2:17 PM
Tiny
KEN L
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Nice, let us know
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Sunday, September 30th, 2018 AT 11:21 AM
Tiny
DAVIDGORDY
  • MEMBER
  • 9 POSTS
Ken, you were correct. The Re man ECM arrived pre-programmed today. I spent an entire five minutes installing it. Said a prayer and turned the key to the on position. The fuel pump primed and shut off as it should so I turned the key to start and it started immediately. It would not idle at first but after keeping it running for one minute with the accelerator until all the fuel components could properly charge and get rid of the air, and also the ECM could make adjustments, All is well. Runs like a champ! Thanks again my friend!
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Wednesday, October 3rd, 2018 AT 12:43 PM
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
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Glad you could get it fixed, that kind of problem can be tough. Please use 2CarPros anytime we are here to help

Cheers, Ken
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Thursday, October 4th, 2018 AT 10:30 AM

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