86 bronco II running bad when hot

[jbgood]

I have a 1986 bronco II, manual 5 speed, 2.9L. Everything is fine as long as the weather is about 70 or so degrees or less. If the temperature outside goes above 70 the engine starts acting like it is running out of gas. It starts bucking and eventually dies. After sitting for awhile, it will start back up and I can drive further but not much as the outside temp is still too hot. when the temp is low, the bronco gives me no problem at all.

[blue beast]

Carry keyboard duster with you and when it acts up hold the can upside down and spray
one electrical component at a time until it runs like normal, once you find the bad part
replace it. Heat raises the resistance and sends screwy readings or cuts out all together.

[1 wrench]

Originally Posted by jbgood

I have a 1986 bronco II, manual 5 speed, 2.9L. Everything is fine as long as the weather is about 70 or so degrees or less. If the temperature outside goes above 70 the engine starts acting like it is running out of gas. It starts bucking and eventually dies. After sitting for awhile, it will start back up and I can drive further but not much as the outside temp is still too hot. when the temp is low, the bronco gives me no problem at all.

The key word you are using is temperature. I have spent the last year rebuilding the same model for my Grandson. We had a similar issue which was resolved by replacing the Temperature Sensor located behind the top radiator hose on the front of the engine. ( the sensor is hidden behind the hose, you have to look for it) For some reason most repair manuals don't refer to this sensor when you have this type of problem. Disconnect the negative on your battery. Drain some coolant ( with engine cool of course) pull the top hose off, removed the thermostat housing, and use an 1 1/8th deep well socket to remove it.
Ensure that you use teflon thread tape on the new switch. Replace parts in reverse order. I hope this helps.

1 Wrench