# My 1989 Jeep Cherokee won't start in warm weather.



## mtlee0321 (May 15, 2008)

My 1989 Jeep Cherokee won't start in warm weather. In cold weather, my vehicle will start every time. Additionally, after I crank the engine and it doesn't start in a few seconds then crank the engine again longer when it does start the engine will rev high, as if additional fuel was being inserted at the start than necessary. In warm weather, when I turn the key the engine just turns over. My vehicle is throttle body fuel injected. Please help.


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## mack1 (Nov 27, 2007)

Hi mtlee0321 and welcome to TSF:wave:

There is a time honored scheme for finding the problem with starting. Determine if the problem is fuel related or ignition and solve the problem from there. This idea has always been there from the earliest times. 

That said, here is a couple of things to do to find the problem.

For fuel problems, get a spray can of starter fluid. Take the large hose loose from the intake manifold and spray the fluid into the intake manifold and try to start it. If it starts and can be kept running by adding more spray, the problem is fuel.

For ignition problems, use a spare sparkplug, or remove one from the engine and lay it on the metal block. Connect the sparkplug wire to it and turn the engine over. Look for a blue spark across the spark plug gap. If no spark or weak yellow spark, the problem is ignition. Some folks simply lift a spark plug wire up from the distributor and watch for the spark there. You can get shocked doing that. If you try that, use a insulated pair of pliars to hold the wire up while watching for the spark jump. I do this, but don't recommend it. Be aware that electrical current that travels through your torso (across the chest) can cause virticular fibrilation. A condition where the heart is said to fibrilate (short pulses that don't pump blood). Someone will need to pound on your chest with a fist to get the heart rythem back to normal. Use the plug on the block, it is safer.

Once you determine the problem (fuel or ignition) post back and there are a lots of folks here that can help you.

Have a nice day.
Mack1


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## mtlee0321 (May 15, 2008)

Thanks Mack 1, for the info. I will try some of those things. I'm pretty sure my vehicle is getting gas, in fact, I believe it is getting too much gas, therefore flooding the engine when starting. Any time I start the engine, whether cold or warm weather, the engine, right after start revs high for a few seconds. I think the computer thinks it is still cold outside. But I'm only guessing. I also replaced the coolant temperature sensor.


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## mack1 (Nov 27, 2007)

Hi mtlee0321,

You might be right. Pull a sparkplug after an attempt to start in warm weather and see if the plug is wet from fuel. 

If your vehicle has a throttle position sensor, you might want to check it for smooth operation. Usually, they receive 5 volts from the computer and that is fed back to the computer based on the throttle position. You can measure the feed back using a volt meter with the key in the on position. Measure the return voltage and watch for smooth operation through the full range of the sensor. You might try unplugging the connector and replugging it in. Sometime dirty contacts can cause problems. 

Best regards,
Mack1


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## mtlee0321 (May 15, 2008)

Thanks Mack 1 for the info on the throttle position sensor. I will definitely find out how that puppy is performing. What you said makes a lot of sense. You the man!


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