1987 Ford Bronco Sudden Stalls

FORD BRONCO
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JSEATON
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  • 2 POSTS
I have a 1987 Bronco 5.0 134000 miles. The engine has been rebuilt and has a new 3 speed transmission. All done within the last year and a half. I can start the truck and the idle jumps up and down periodically. Sometimes it jumps alot, up to around 1500 rpm. Going down the road it shows no sign of quitting, no sputters or power loss, then all of a sudden the rpm's go to 0 and there is no response from the accelerator. Now as long as the truck keeps rolling down the road I have power steering and my guages all give readings, but when I slow down to around 10 miles an hour my steering goes away, all my gauges go to nothing and I hear my fuel pump reinitialize the system. Also at that point my check engine light comes on but not until that point when I slow down. I'm at a loss here, any information would help. I realize it could be one of a hundred things, but could you give me a few to try
Sep 22, 2006 at 8:58 AM
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NOS
  • ✓Experienced Mechanic
  • 320 POSTS
sorry some where in there when i was reading i didn't see it saying that the engine is stalling is the engine still running when this does this? the plug that goes to the coil has had problems over the years that is where the tach referance comes from. if you looseing that that means you looseing spark as well. also check your wireharness real close to make sure all has a good connection.(NOS) 8)
Sep 23, 2006 at 8:53 AM
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JSEATON
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Sorry, I can't tell if the engine is running when the RPM's go to 0, I don't think it is though, but like I said I still have power steering until I slow down to around 10 MPH, so that would have to mean that the power steering pump is still going. Now when I said going down the road, it did it once when I was going 45 mph at 2000 rpm, I lost power and coasted down to about 10mph and then everything shut off and the check engine light cut on. So you are saying to make sure the wires going into the wiring harness for the coil have good connection? If that is what you mean then I have looked at those and they do look bad. Looks as if soemone has tried to rewire that once before. I'll try that.
Sep 25, 2006 at 10:38 AM

Suggested Repair

Inspect and repair the coil plug and nearby wiring harness connections. A poor connection there can drop the tach reference and spark, causing a sudden stall.

Conversation Summary

The owner of a 1987 Ford Bronco 5.0 reports unstable idle and sudden stalls while driving, with RPM dropping to zero, no throttle response, gauges dying after slowing, the fuel pump reinitializing, and the check engine light coming on. The expert asked whether the engine was still running and advised checking the coil connector, which supplies the tach reference and spark, plus the wiring harness for poor connections. The owner said the coil wires look damaged from a prior rewire and planned to inspect them.

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