87 YJ 4.2 man trans immediate shutdown after starting

S

Shaker

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May 12, 2021
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Md.
The wife and I recently had a nice 87 Yj given to us and we have an issue I cant narrow down. Engine starts and shuts right back down. I have ordered all new parts for it so it is up to date. Had a new carb installed prior to us taking it and all the vac lines seen good but also will be removed or replaced. Changed the fuel pump, gas filter, ( added a new glass filter prior to pump to visually monitor the sediment coming from the tank.) plugs wires coil and restabbed the dist. to get back in time. Has to be electrical. I have sprayed fuel in the carb upon start up with no effect and I am left scratching my head. Could someone help me narrow my search for possibilities. 168,000 miles so I also have ordered an HEI style distributor. I don't want to start doing further updates ie.. the water pump hoses belts etc until i know I can get this puppy runnin. The plugs were caked with carbon as well when removed. I am thinking the auto shutdown relay or ECM but don't know where to find the relays as of yet if there are any as it is a carb engine with mechanical pump. Any advice or criticism is welcome at this point in time.

Shaker
 
Shaker said:
The wife and I recently had a nice 87 Yj given to us and we have an issue I cant narrow down. Engine starts and shuts right back down. I have ordered all new parts for it so it is up to date. Had a new carb installed prior to us taking it and all the vac lines seen good but also will be removed or replaced. Changed the fuel pump, gas filter, ( added a new glass filter prior to pump to visually monitor the sediment coming from the tank.) plugs wires coil and restabbed the dist. to get back in time. Has to be electrical. I have sprayed fuel in the carb upon start up with no effect and I am left scratching my head. Could someone help me narrow my search for possibilities. 168,000 miles so I also have ordered an HEI style distributor. I don't want to start doing further updates ie.. the water pump hoses belts etc until i know I can get this puppy runnin. The plugs were caked with carbon as well when removed. I am thinking the auto shutdown relay or ECM but don't know where to find the relays as of yet if there are any as it is a carb engine with mechanical pump. Any advice or criticism is welcome at this point in time.

Shaker
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You don’t have a true ECM or auto shutdown relay on an 87.
They do have an ignition control module though so maybe replace that. Sorry, don’t know a ton about troubleshooting a 4.2L.
 
jeepjoe43 said:
Does it die during cranking, right when you let off the starter, or shortly after?
Could be as simple as the ignition switch..
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Sorry just read this. I just posted an update as I have nothing to lose by goin old school. I did however notice the switch was acting weird but there have been so many hands in this pot I gonna start from ground zero and go old school. Need help with that as well.
 
As for the question you asked. I would turn the key it would fire and shut down before I even had a chance to release the key. Adding starting fluid to test didnt even effect it so it has to be electrical in my mind and electrical aint my fortay lol.
 
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