Engine runs but dies and will not restart until you unhook battery and hook back up.

Tiny
S10ROCKET
  • MEMBER
  • 1991 CHEVROLET SILVERADO
  • 7.4L
  • V8
  • 2WD
  • AUTOMATIC
  • 95,000 MILES
OK, first it started with a what seemed to be bad fuel pump problem. We replaced the fuel pump and it seemed to snowball from there. Now our issue is, when you turn the key forward, you will hear some solenoids click and then the fuel injectors will fire and a little fuel will go into the bowls. Turn the key further and it starts, sounds normal? After running for a while under driving conditions or idle conditions, it will die. When you try and restart it, nothing, just cranks. When you check it again, to hear the clicks, no fuel injectors will fire, but you do here other solenoids click. Now, if I unhook the battery and hook back up, the engine starts right up again and goes through the same song and dance. We have replaced the fuel pump, fuel filter, AIC, TPS, Fuel Pump Relay, rebuilt TBI, and we are going to replace the MAP sensor and the Coolant Temp Sensor, just to make sure we have done them all. We need some help here, Sensors are expensive and we are quickly running out of sensors to change. A little history of the truck, my dad has owned it since 2005 and only put 4500 miles on it pulling a camper a couple times a year so sitting all the time has not been very healthy on the truck. When he bought it, it had all of the high performance ignition stuff on it but over the years it has all gone bad so we have switched it back to stock. I am wondering if it may be the Computer since if I unhook the battery it starts up fine again until it dies?
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have the same problem?
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No
Sunday, October 4th, 2015 AT 7:05 PM

25 Replies

Tiny
JACOBANDNICKOLAS
  • EXPERT
What trouble codes are you getting? When it stalls and won't start, are you getting spark? You mentioned no fuel.

Also, is the ECM a GM component or has someone replaced it to? Since there were aftermarket ignition components, I'm concerned someone may have changed the prom or messed with it.
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Sunday, October 4th, 2015 AT 7:51 PM
Tiny
S10ROCKET
  • MEMBER
I have no way of checking codes here at the house, and Yes it is getting spark when it dies.
I have a buddy that can scan it but he is out of town for the next week. He has one of the cheap scanners from the parts store. I will see if his son can bring it over and I will try and get the codes out of it.
As for the ECM, I have not removed it to take a look at it, what would an aftermarket ECM look like apposed to a oem one?
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Sunday, October 4th, 2015 AT 8:05 PM
Tiny
JACOBANDNICKOLAS
  • EXPERT
You don't need a scanner to check codes. On the OBD plug, locate port A and B. Place a paperclip between the two and turn the key to the run position (engine off). The codes will be 2 digit numbers. The check engine light will flash, pause, and flash again. Count the numbers of flashes to determine the 2 digit codes. The first one should be a 12.

As far as the ECM, most high performance ones will have their names listed on them. As far as different chips / proms, that is going to be a tough one to identify.
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Sunday, October 4th, 2015 AT 8:20 PM
Tiny
JACOBANDNICKOLAS
  • EXPERT
AFTER THOUGHT:

You know, if you have spark and fuel, it should run. Try this. When it won't restart, see if it will start a couple seconds using starting fluid. If it does, then we have good spark but no fuel. If that is the case, check to see if you are getting a pulse to the injectors. We may be losing communication between the ECM and the injectors.
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Sunday, October 4th, 2015 AT 8:22 PM
Tiny
S10ROCKET
  • MEMBER
The OBD plug is under steering wheel correct?

Also, when it dies, the fuel injectors don't fire when the key is turned to the on position. Once you unplug the battery and reconnect they fire.

I will check codes in the morning.

Thanks
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Sunday, October 4th, 2015 AT 8:53 PM
Tiny
S10ROCKET
  • MEMBER
Well, I just checked the codes and all that flashes is a 12, over and over and over.

Also, the check engine light is not on this morning and it has throttle response. Yesterday just the opposite, throttle hesitation and a check engine light. Tomorrow it may be back to hesitation, this is something else that it is doing, seems like it just depends on how it wants to run each day.
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Monday, October 5th, 2015 AT 6:04 AM
Tiny
S10ROCKET
  • MEMBER
As for the ECM, everything appears to be factory.

Did you have any suggestions, have not heard anything since yoru last reply?
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Tuesday, October 6th, 2015 AT 12:33 PM
Tiny
S10ROCKET
  • MEMBER
Also, today I tried to read the codes because the check engine light was back on and I can't even get it to flash 12 now! I am so frustrated I cant see straight.
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Tuesday, October 6th, 2015 AT 2:32 PM
Tiny
JACOBANDNICKOLAS
  • EXPERT
Sorry I haven't gotten back with you. We had a death in the family. Regardless, if it is running good, I have to question sensors. You mentioned that the injectors don't have power when it won't start. Did you check them with the engine cranking? Will the engine start with starting fluid when this happens?
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Thursday, October 8th, 2015 AT 8:01 PM
Tiny
S10ROCKET
  • MEMBER
Sorry for bothering you in your time of mourning, if you need time I understand.

To answer your question, yes it will start, but just until the fluid is gone though.
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Friday, October 9th, 2015 AT 1:53 PM
Tiny
S10ROCKET
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Also, checked again today and the truck was fine, flashing 12 again. Yesterday and the day before, would not run well, same issues.
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Friday, October 9th, 2015 AT 7:41 PM
Tiny
JACOBANDNICKOLAS
  • EXPERT
It almost sounds like the ECM is going bad. That is what signals the injectors to fire. Check to make sure wiring to them is clean, tight, and there is no damage. Check where the harness plugs into the ECM as well for pin issues.
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Monday, October 12th, 2015 AT 5:08 PM
Tiny
S10ROCKET
  • MEMBER
Ok, I will check everything. If I have to replace do you suggest new, reman or wrecking yard? Also what vehicles will fit the truck?
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Monday, October 12th, 2015 AT 8:04 PM
Tiny
S10ROCKET
  • MEMBER
Pulled ECM today, all of the connections and pins look to be fine. Now the problem I am having is, the part number on the ECM does not match anything I can find online. It says 1GM0164953 AWAP, have any idea if that is an aftermarket number and what unit I would use if it is?
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Tuesday, October 13th, 2015 AT 4:45 PM
Tiny
JACOBANDNICKOLAS
  • EXPERT
Sorry for the delay. I was out of town for a family issue. As far as the part number, I would suggest contacting a local parts store to see if they have what you need. If you get one off line, it is hard to tell what you'll receive. As far as part numbers, I don't get them too often anymore, but I had a 93 olds in last week. Similar problem which I diagnosed as the PCM. I got one from the local parts store and it listed three different part numbers which were interchangeable. I removed, switched out the prom, and reinstalled it and the car ran perfectly. Contact them. Also, see if someone in your area will test the one you have. I will feel really bad if that isn't the issue and you spend money for the part.
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Monday, October 19th, 2015 AT 5:27 PM
Tiny
S10ROCKET
  • MEMBER
I put a new ECM in and it seems to run better, now it will not shift, worked fine before it was towed to my house. Moves in reverse and first gear, nothing after that, GEESH, one thing after another. Any suggestions on that?
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Monday, October 19th, 2015 AT 7:43 PM
Tiny
JACOBANDNICKOLAS
  • EXPERT
Is the PCM new? Have you checked to see if there are any new codes? Also, are you sure none of the pins in the connector aren't damaged or pushed in?
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Tuesday, October 20th, 2015 AT 5:36 PM
Tiny
S10ROCKET
  • MEMBER
Well, it's a reman ECM, no pins bent. As for codes, still will not allow me to read them, I put the jumper in A-B and the light will stay on, no flashing at all, only got it to do that one time and it flashed 12. Everything appears to be correct.
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Tuesday, October 20th, 2015 AT 7:35 PM
Tiny
JACOBANDNICKOLAS
  • EXPERT
Did you put your prom into the new PCM?
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Thursday, October 22nd, 2015 AT 5:23 PM
Tiny
S10ROCKET
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Yes, I put the prom into the PCM.
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Thursday, October 22nd, 2015 AT 7:35 PM

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