My father bought a 87 Bronco II XLT when I was around 6, so selling it is out of the option. About a year ago, I took it to a backyard mechanic to "fix it". What was wrong was it would lose power on hills and not make it above 55 mph. I am unclear of what all he did, but I know he replaced the heads, distributor, and spark wires. I got it back and because of some registration problems I wasn't able to drive it right away. Anyways I drive it regularly now, because it is my only vehicle, and the problems, if anything have worsened. When I first start it in the morning, its fine, normal power and everything. But once it heats up, it starts losing massive amounts of power. It sounds like a ticking in the engine. I've adjusted both sides of valves and the problems still happen. No matter how far the pedal is pressed, the tachometer stays at around 2-2 1/2 G. To get it up to speed, you must rev it as far as it will go, then let off to let it downshift and repeat. Still this only gets it up to 45-55 mph. That's the mechanical trouble. Before I took it to the mechanic, I installed a sound system. It worked fine before and after I got it back from the mechanic. I let it sit while I tried to register it. Then all of the sudden, the radio and amp wouldn't turn on unless the lights were turned on, the fuel and temp gauge stopped working, the windshield wipers stopped working, and the windows didn't roll down. All of this on one vehicle. Please help. Any info would be useful.

 

Since it runs normally before it warms up that implies it's running okay in open, but not in closed, loop. Try removing the spout connector before going for a drive. This will prevent the computer from controlling the ignition timing when the system goes into closed loop. Does it run better now? If so maybe the EEC IV computer is toast. Does the service engine light work? Is it on all the time? If not I'd check to make sure that everything checks out okay anyway. Another thing to check is the O2 sensor since that provides feedback control over the fuel injectors. Make sure it cycles normally by measuring its voltage. I don't think I'd worry too much about the electrical gremlins until it runs normally.

 

If you want to try plilikoi's idea the spout lays on top of the passenger side valve cover. If it runs the same it means the spark advance is'nt working.

You said it wont run above 2500 RPMs, that could be caused by a clogged fuel filter or a clogged exhaust.

Theres lots of online info to tell you how to test for a clogged exhaust with a vacuum gauge. It's a very simple test. Goggle it

1988 was the 1st year that had a CEL/check engine light on the dash. An 87 does'nt have a CEL, so you need to pull the trouble codes, which is also very easy to do. An equss 3145 scanner is about 25 bucks and VERY easy to use. Sometimes pulling the codes will tell you exactly what the problem is & it only takes a couple of minutes.

 

Thank you so much for theses suggestions. It is so hard to find information regarding bronco II's. I will try these as soon as I can.