86 Bronco II Intermittently dying

[steve1978]

As stated in the title 1986 Bronco II 2.9L V6 Automatic

The truck would just shut off while driving anywhere over 15-20 mins of running; its like a deathly silence when the motor cuts off. Thing is after about an hour or so of cooling down, she starts right back up again (then rinse/repeat); which leads me to believe it may be pressure/compression related issue due to the motor getting too hot. The intermittent shut off happens more often during the summer season when temps reaches anything above 25C/77F and the engine bay is just HOT. During winter season with temperatures below freezing the truck runs fine, i haven't actually ran it until it dies...but at least i can still run around and do my groceries on the weekends; typical day-to-day its a 5 min drive to the station and i take transit the rest of the way to work so in that sense i don't stress the vehicle much.

Now that summer is coming up, i was hoping to pick your brains on what could possibly be the problem...sort of gauge where i should start in (hopefully) remedying this. If you need more info please ask, not sure what else i can provide...other than during the high ambient temps it dies; the truck ran fine for the past 23 years (one and only owner)

*Initially i thought it was the ignition module on the back of the distributor, that has since been replaced. Ignition coil and ignition leads replaced. Coolant/Oil all flushed and refilled. Thermostat/Coolant lines replaced. Gauges read nothing abnormal...don't know what it could be...

 

[FordBroncoII]

Ideas:

A) High Temperature and fuel cut-off with sensors: fuel, temperature, pressure sensors?

B) High volume of gas and other vapor build-up with high temperatures - related to the emissions system?

C) Voltage regulator malfunction?

 

[BroncoJoe19]

Next time it stalls check to see if you have spark. IF NOT, it may be a bad picklup coil inside the distributor, or bad ignition module, well I guess it could be a bad ignition coil.

At any rate, do you know how to check for spark?

 

[steve1978]

FordBroncoII- Yeah i've been thinking about that too, that it may be fuel related causing some sort of vapor lock

BroncoJoe19- I've already replaced ignition module and coil. Please refresh my memory, how do you check for spark again? Do i pull one of the ignition leads, ground to the frame and check for spark?

damn i need a service manual to locate these sensors/probes.

Thanks for the help

 

[scott.thunder]

you could always do it the redneck way, well my way just pull one of the plugs wires at the spark plug hold it close to engine block making sure your finger isnt in between and have someone crank the engine, if a spark comes out and grounds on the engine o plug you have spark.

 

[BroncoJoe19]

I like to use a spare spark plug. Pull a wire, insert the spare plug, and then ground the plug to the block or something handy, and then like posted above, have someone crank the engine.