b.chaffe

A recent problem has come up with my '89 Bronco 5.0L V8 automatic (fully stock); after being driven for a while (45min. to 1 1/2hr.) and once the Bronco is up to full operating temp, parked for 20 min to an hour, then during driving the Bronco will stop running until cooled down for approx. 2 hours. After cool down, it runs fine. According to temp gauge it has not overheated and it has never boiled over. Coolant level is good, engine oil level is good. This problem came up a few weeks back, since then Bronco runs fine for short drives around town and for longer drives with adequate cool down. Looking for suggestions on where to start with troubleshoot.
Thank you.

847alexc

Just a thought, perhaps your are have a bad coolant temp sensor. This is not to be confused with the sending unit.

Clearly, your engine is running in the normal range as it is not boiling over and the gauge agrees with that. But, while the sending unit feeds the reading to the gauge, the sensor sends information to the computer for fuel trim curve and the like.

Perhaps it is worth checking the sensor against the specs. Haynes and Chilton's manuals generally will have the proper resistance values and procedure for your application. Otherwise, if you have access to a computer tool that can give you digital readout of the sensor value, which might prove more helpful.

Steve83

Neither the gauge sender nor the ECT sensor will cause the engine not to run.

Buy a Haynes manual (the older, the better) and test the coil using a cheap digital mutimeter. If it passes, test the whole ignition system per Ch.5 .

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847alexc

While you are likely correct, as most of your posts have shown, I have to inquire...

You don't think that a temp sensor telling the computer that the engine is still cold could stall the engine at high temps?

First, it would prevent the computer from coming out of closed loop mode to use all of the other sensor values. Second, it would likely cause a rich mixture and potentially flood the motor.

I don't disagree with your suggestion, but why would a bad coil only cut out at high temps?

I might add that both would lead to the smell of unburned fuel.

cjdunn09

i had the same problem with my 89 bronco 2 2.9 v6 it turned out it was the fuel pump. test it by letting the truck warm up or get to the point it wont start, then have someone tap on gas tank while you try to start it. I found this out 14,000 miles away from home

g_k50

Check fuel pressure the next time it acts up, I think you'll find it too low, indicates new fuel pump.