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[Solved] 1989 bronco that commonly stalls when braking as well as going over a decent bump in the road


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I have a 1989 Ford bronco. Eddie Bauer with the 5.8 liter. I got this car with virtually everything stock in 2017. It was garage kept. Barely a 100,000 miles on it. It was my first car and was going to be my project car. Anyways fast forward to 2023, it’s spent more time at a mechanic than I have driven it. It had a leaking main seal when I got it so I was adding a quart of oil a week at least. Dealt with this for a few years while saving up the money for a new engine. I got a remanufactured engine and had my mechanic install it. He has my full confidence. When my dads work truck was stalling due to an improperly timed distributor this guy had it figured out in two days when Ford dealership for 3 months couldn’t do nothing. Anyways after then engine was installed a lot of minor problems went away. How ever the stalling and braking persistently got worse over time. I went through the fuel system. Small leak on the second fuel pump under the driver seat. No problem. Thought this could be a good reason. Replaced said fuel pump. And virtually the rest of the fuel system. All filters. I lowered the 32 gallon beast of a fuel tank. Replaced the fuel pump and the whole fuel sending bracket and treated for some minor rusting. Reinstalled. Replaced several old lines. Helped a little bit did not solve issue. Put a fuel pressure regulator on there and drove it. It was consistent and never losses pressure. I decided to look for vacuum leaks. I have gone through each line replacing many. I replaced the brake power booster as my mechanic told me it was bad. After a few defective power boosters I got one on there that worked. Smoke tested it, no leaks. Once again did not solve problem. Though I had the brakes all redone including master cylinder. Stops like a dream now and rides smooth. Until it dies…. I’ve gone back to my mechanic and explained the situation. He dived in. However. 4,500$ and 4 months later I’m still dead in the water. All the fuel injectors have been replaced. New map sensor. Egr sensors are mostly new. New o2 sensor. Cats on it have minimal miles. TPS is new. I have checked voltage and ohms on everything I can think of. I have used the ford OBD1 diagnostic system multiple times but none of the codes have been life changing if there is any. My mechanic has tried 4 different distributors. 3 of them ran worse. He got it going good with the 4th one. Replaced the ignition control module on it. Replaced Idle air control valve. The throttle body and virtually everything near it and on it is new. After the distributor it seemed to run great. Until the next day he started it up and it back fired and ran worse than ever. We have begun replacing the wire harness and have replaced it all the way to the ECM. My mechanic has tried a number of ECMS. I don’t think I need to say that it did not resolve the issue. When it dies the tachometer is all over bounces between 700 and 300 before it dies. He has checked so many electronics. He has checked the kill switch that shuts off engine in the event of major accident. He’s checked for shorts in the dashboard that have been rumored to cause problems. I’m totally stumped. At this point my mechanic is working on it for free. But I can’t expect that forever. The only piece I haven’t replaced is the 3 speed transmission. It’s a sturdy build with no electronic crap.  I’ve never had any problems with it. I’m desperate for help
I love this bronco. But I can not afford to be working on a car I can’t drive. If I can’t get it fixed soon. I’ll have to sell it.  

1 Answer

As you find old Fords have all kinds of problems. I would start by doing a wet and dry compression test of the engine to make sure the engine is good cuz if it isn't good I'd stop right there. Now if it is good being an 89, I'd start by checking all the wiring connectors and wiring harnesses all often get cracked short out. Need to be rewired when they're that old