89 YJ 258 starting problems when warm - choke stays closed - please help - Jeep Wrangler Forum
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Old 01-30-2011, 11:08 AM   #1
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89 YJ 258 starting problems when warm - choke stays closed - please help

I need help with starting problems on my 1989 Jeep Wrangler, 258 inline 6.

It will start when cold, or when hot - typically. Not when warm. If I wait a few minutes after it is running to try and restart, it will turn without cranking.

It appears the choke plate stays closed when it doesn’t start. Mainly from reading this post (http://www.carkb.com/Uwe/Forum.aspx/jeep/9932/87-wrangler-starting-problem-HELP), I learned that sticking a screwdriver to hold the choke plate open will allow it to start.

Fuel delivery: replaced fuel pump, filter x2, plenty of gas reaches the carb, replaced the gas to rule out water

Ignition: spark at the plugs ever time I have checked. Replaced ignition coil, rotor, distr cap, and the ignition module was replaced about 18 months ago.

Starter, Battery and Alternator all perfect.

Vacuum: fixed 3 leaks in my vacuum hoses. One tube to the vacuum reservoir was disconnected. Hole in the tube to the sol-vac solenoid (this helped idle RPMs but not the start problem), and one tube from the charcoal canister to my gas tank vent. Also, I have plugged the air purge system due to old rusted pipes to the exhaust.

I replaced the carb with a rebuilt model about a year ago. I assume all the adjustments on the carb are okay. I replaced the choke pull off as well again and no fix.

I have been unable to replace my 02 sensor (stripped) but when I disconnect it there is no additional problem.


? MCU (microcomputer unit) is at the top of my list – is this a possibility?
? Ignition Module defective again
? Electric choke defective?
? undiagnosed vacuum leak or clog or solenoid bad

Thanks in advance,
Will

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Old 01-30-2011, 03:09 PM   #2
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do you still have all the original emmisions and those things connected??

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Old 01-30-2011, 03:47 PM   #3
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If your engine is warm, your choke plate should NOT be closed. If it is just loosen the 3 screws on the choke thermostat , WHEN WARM, and turn it until plate opens enough for vehicle to start.
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Old 01-30-2011, 04:52 PM   #4
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put a weber carb, buy a isolated ignition and rip out all your emmisions and your computer and all that other useless crap and ull never have a problem again. At least thats what i did
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Old 01-30-2011, 05:13 PM   #5
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Quote:
Originally Posted by thowild View Post
I need help with starting problems on my 1989 Jeep Wrangler, 258 inline 6.

It will start when cold, or when hot - typically. Not when warm. If I wait a few minutes after it is running to try and restart, it will turn without cranking.

It appears the choke plate stays closed when it doesn’t start. Mainly from reading this post (http://www.carkb.com/Uwe/Forum.aspx/jeep/9932/87-wrangler-starting-problem-HELP), I learned that sticking a screwdriver to hold the choke plate open will allow it to start.

Fuel delivery: replaced fuel pump, filter x2, plenty of gas reaches the carb, replaced the gas to rule out water

Ignition: spark at the plugs ever time I have checked. Replaced ignition coil, rotor, distr cap, and the ignition module was replaced about 18 months ago.

Starter, Battery and Alternator all perfect.

Vacuum: fixed 3 leaks in my vacuum hoses. One tube to the vacuum reservoir was disconnected. Hole in the tube to the sol-vac solenoid (this helped idle RPMs but not the start problem), and one tube from the charcoal canister to my gas tank vent. Also, I have plugged the air purge system due to old rusted pipes to the exhaust.

I replaced the carb with a rebuilt model about a year ago. I assume all the adjustments on the carb are okay. I replaced the choke pull off as well again and no fix.

I have been unable to replace my 02 sensor (stripped) but when I disconnect it there is no additional problem.


? MCU (microcomputer unit) is at the top of my list – is this a possibility?
? Ignition Module defective again
? Electric choke defective?
? undiagnosed vacuum leak or clog or solenoid bad

Thanks in advance,
Will
Ignition module can go bad. The same happen to me. It took 6 months for the new module to go bad.
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Old 01-30-2011, 05:19 PM   #6
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the ignition control module is the thing on the firewall witch doesnt effect the carb, i believe all it does is control when the spark plug fires. i have removed mine b.c i replaced 10 in a year so
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Old 01-30-2011, 05:39 PM   #7
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Quote:
Originally Posted by sppfields View Post
If your engine is warm, your choke plate should NOT be closed. If it is just loosen the 3 screws on the choke thermostat , WHEN WARM, and turn it until plate opens enough for vehicle to start.
I basically agree with this. Clean your carb. real good with carb. and choke cleaner, all of the linkage etc. Then, set your choke thermostat to the 1 notch rich setting. These carbs seem to like that setting the best. As you move the spring you should see that the plate is also moving. If it doesn't then it's malfunctioning. You'll have to address the issue another way such as a mechanical choke which isn't difficult to install. See if the cleaning and setting it solves the problem first. It's the quikest and least expensive fix. As far as the Ignition Control Module, on a stock 89YJ 4.2, it is located under the coolant expansion tank and is held on with 3 10mm bolts. It controls spark to the coil basically. That is not your problem. It only appears to affect the carb. if the coil is not providing the proper spark to the system which makes it seem that the carb. is at fault. You have a choke and/or a choke linkage problem because it does run fine as you said cold or hot.
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Old 01-30-2011, 05:48 PM   #8
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ya putting a manual choke on would be your best bet, thats what ive been thinking about doing with my weber

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