CJ7 Starts and Dies Immediately - JeepForum.com
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post #1 of 15 Old 08-03-2021, 06:22 AM Thread Starter
Mobymadness
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Cj CJ7 Starts and Dies Immediately

Good morning. Struggling with my 84 CJ7.

It starts over and runs for a second. Then dies.

Things I have done to try and fix this.
  • Fuel Pump
  • Filter
  • Distributor cap
  • Spark plugs and wires
  • New Carbeurator
  • New Battery with cables
  • Tested the ignition solenoid

I have also checked for vacuum leaks and not been successful in finding any. I am going to replace the starter solenoid tonight as well as the EGR valve.

Not sure where to head next or what to look for. It ran great a few days ago.

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post #2 of 15 Old 08-03-2021, 06:54 AM
Matt1981CJ7
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Does it repeat the start/die sequence each time you attempt to start it up?

Or, after it dies once, does it take a while before it will fire again?

Matt


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post #3 of 15 Old 08-03-2021, 07:56 AM
Fourtrail
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Sounds like your ignition switch is out of adjustment, you might be loosing power to the ignition box and coil once you release the key from the start position back to the run position. Need to check for approx 9v at the coil and 12v to the ignition box with the key in the run position
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post #4 of 15 Old 08-03-2021, 09:19 AM
Matt1981CJ7
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Quote:
Originally Posted by Fourtrail View Post
Sounds like your ignition switch is out of adjustment, you might be loosing power to the ignition box and coil once you release the key from the start position back to the run position. Need to check for approx 9v at the coil and 12v to the ignition box with the key in the run position

This is good advice, as usual from Fourtrail.

I'll add a warning. Don't leave the key in the run position for too long while doing your testing. Otherwise, you risk burning up the ICM and coil.

Good luck,

Matt


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post #5 of 15 Old 08-03-2021, 10:00 AM
John Strenk
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Also the resistor wire from the switch to the coil could be bad.
The jeep runs off the Ignition bypass from the starter solenoid. But as soon as you let off the key, it has no more power.
Look for a bad splice near the bulkhead connector or a broken/ loose wire on the ignition coil plug.

Do you have a DVM? you can check the voltage at the (+) terminal on the coil when the key is in the run position. That would be a big help as far as trouble shooting.
Should be around 9 volts. Don't leave the key on for long though. As Matt pointed out, you will be replacing your ICM.

But as usual, I would also suspect the ICM is also bad. He should be able to take it in to get tested. Just can't deliver enough power to keep it running.

I would not replace the starter as yet...


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post #6 of 15 Old 08-03-2021, 10:19 AM
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Run a wire from the battery POS to the POS side of the coil.
If it runs, look hard at your ign switch.
Gary
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post #7 of 15 Old 08-03-2021, 05:42 PM Thread Starter
Mobymadness
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Quote:
Originally Posted by Matt1981CJ7 View Post
Does it repeat the start/die sequence each time you attempt to start it up?

Or, after it dies once, does it take a while before it will fire again?

Matt

Once it dies, it takes a while for it to fire up again. It takes the help of some starting fluid too.
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post #8 of 15 Old 08-03-2021, 05:51 PM
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Quote:
Originally Posted by Mobymadness View Post
Once it dies, it takes a while for it to fire up again. It takes the help of some starting fluid too.

Does it die when you let off the key from cranking, or does it run a bit after you let off the key then die? Have you checked to see if you are getting fuel from the pump when cranking? If you have a bad rubber line, you may not be pumping fuel when cranking, or just enough when cranking to get it to run for a short time. I would pull the fuel line off of the carb and make sure you are getting good spurts of fuel when you are cranking.


You can also fill the fuel bowl through the vent to see if it runs longer with a full float bowl.

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post #9 of 15 Old 08-04-2021, 06:43 AM
Matt1981CJ7
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Quote:
Originally Posted by Mobymadness View Post
Once it dies, it takes a while for it to fire up again. It takes the help of some starting fluid too.
OK, that's important information.

I'd start with confirming you have fuel getting to the carb, as Fourtrail suggested.

Let us know, and we'll go from there.

Matt


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post #10 of 15 Old 08-04-2021, 07:02 AM
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This is beginning to sound like the time I had a pinhole leak in my fuel line back near the tank.

This goes along with what Fourtrail is talking about checking the fuel pump is pumping correctly.


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post #11 of 15 Old 08-04-2021, 09:23 AM
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Check the color of the spark. Could also be a bad coil.
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post #12 of 15 Old 08-04-2021, 09:54 AM Thread Starter
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Thanks all. I’ll start testing some of this and report back. In the middle of relaxing the intake/exhaust manifold gaskets. Once it’s back together, it’ll have a new EGR valve and ignition coil.

Mark
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post #13 of 15 Old 08-04-2021, 10:39 AM
mudbfun
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Check for spark the next time it wont start. It could be a fuel or ignition problem, that will help narrow it down. Besides the many good suggestions above you could also be dealing with a bad control module.
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post #14 of 15 Old 08-04-2021, 01:50 PM
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Yes, check for spark. You can buy cheap plug tester that go between the plug and wire to see if each plug is getting fire.
Check your ignition module connection. I had one that had a couple cuts in the wires causing it to arc once in awhile and die and not start for awhile.
But if its a fuel issue...don't forget the sock filter in the gas tank. Went through a list of parts decades ago trying to figure out a similar die/no start issue...finally it was the $5 sock filter collapsing with 1/4 or less showing on the gauge.

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post #15 of 15 Old 08-08-2021, 07:54 AM Thread Starter
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Got it running.

I was getting fuel when giving it throttle but I guess I wasnít getting any at idle. So I traced it back to the fuel tank. Dropped the tank and discovered the sending unit was toast. Iím thinking there was not enough vacuum at idle to get through the system. I changed that out and it runs great now. I also replaced the ignition coil when it was down.

Thanks for the help, all. Now, itís time to replace the valve cover.
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