I just bought a 1988 Bronco XLT 4x4 with the 302 and the AOD trans. I drove it around town for a day and it ran really well, but when I drove it 15 miles to where I work I ran into problems. First, I noticed that at a steady speed of 50mph intermittently I was getting a check engine light, and it felt like she wasn't all there at the pedal when that light came on. I pulled over at a gas station, put gas in it and checked my fluids, and I was about a half a quart low on oil. There was nothing on the ground under the truck, so I bought a quart of oil and left for work. Then when I came to a stop at a red light with the truck in gear the oil pressure gauge dropped and I got red light that said 'ENGINE'. When I gave it gas again and took off, the oil pressure gauge came back up, and the light went away. But every time I came to a stop the same thing happened. When I went on break I took my supervisor on a test drive b/c he used to have a bronco and is pretty good with cars. We drove it down the street and the first time I came to a stop the oil pressure gauge dropped to nothing, the red engine light came on, and the truck stalled and would not start again. There were no fluids on the ground under the truck. We dragged it back to our lot with a chain, and I was able to get it started so I backed it into a spot and parked it. I have no clue what's wrong with it so I thought I would ask the forums. Any and all help would be greatly appreciated as I now have $10,000 invested in my two trucks and neither of them drive down the road. So this is my nightmare, give me your input.
Thanks guys,
Art

 

If I recall correctly, the oil pump is driven by a hex shaft that indexes with the bottom of the dist shaft. The cam turns the dist shaft which turns the oil pump hex shaft. You might want to check the hex shaft for the high points rounding off. If that is all that's wrong with it, shaft replacement is all that is necessary. As I stated, this goes back a way and I could be wrong.

 

Ok guys, time for an update. So the bronco sat in the parking lot for 3 days while I tried to get it running. I was losing a lot of oil (a quart and a half in 20 miles). But I couldn't find any oil on the ground. That's not why it wouldn't start though. We thought it was a fuel issue so I put a new fuel pump in it in the parking lot. It started, but I put it in gear. tried to drive it, and she stalled after 10 yards. I hated to do it, but I called a flatbed and had her brought here. After we installed a new cap and rotor we were able to get it running yesterday before we started work. It ran for 10 minutes straight while we had the computer on it. We have been working on it nonstop from dawn to dusk for two days. So here's what I've found out. Blown out valve cover gaskets on both sides, leaking onto the manifolds so it was evaporating before it could run to the ground. So we replaced the gaskets. Also, we replaced the cap, rotor, plugs, wires, coil, pcv valve, fuel filter, fuel pump, oil sending unit, and fuel pump relay. This morning after we finished hooking everything back up, I started it and it ran for a couple minutes, and then shut off. We were not getting power to the fuel pump. The brown wire at the relay has no power. We kind of bypassed it with a piece of wire to get power to the fuel pump. Now we have 40 psi of fuel pressure at the rail with the key on, but the truck still won't start. If we spray carb cleaner in there it will start, and if we keep spraying it it will run but as soon as we stop she dies. We thought for sure that replacing the relays would fix it, but to no avail. My truck still won't start, and I'm out of ideas. Please help.

 

When you turn the key on you should have power to the coil. With a test lite connected to the positive terminal of the battery and the test lite contacting the other terminal of the coil the test lite should flash,does it? If not check the pick-up coil in the distributor , it may not be working or could have some poor connections.

 

Updating again as I have just now stopped working on her for today. We tested the injectors and they are NOT pulsing. Replaced distributor module/ignition module on the side of the distributor. No dice. I've ripped the computer out. It's sitting on the kitchen table, it looks like it has water damage; there is corrosion all over one side of it. I've ordered another one it should be here tomorrow. I've got my fingers crossed because after this I am completely out of ideas for this darn thing. Still want to hear what you guys think, please reply.
Thanks,
Art.

 

The only thing that doesn't have power is a brown wire connected to the fuel pump relay, and the fuel injectors aren't pulsing.

 

So I put the new computer in yesterday, hit the key, and she fired up! She ran like a champ for a few minutes, no misses, no struggling, nothing like that. And then she just quit. Didn't sputter or idle funny or anything was running fine one second, and the next she just died. And wouldn't start again.:wtf

 

Let's hope you didn't wipe out another computer.
Now it's back to basics.
Do you have spark available at the /any spark plug(s)?
If you do have spark available give the air filter a shot of carb and choke cleaner then try to start it. If it runs for a few seconds there is a fuel supply problem.
Let us know what you found.

 

Things haven't changed. I'm thinking we have an electrical issue that is causing the injectors not to open. I have spark everywhere, fuel pressure at the rail, she should start right up. but she don't. No power going to the fuel pump so we bypassed it at the relay. The fuel pump has constant power right now as a result. Whenever the key is on. Maybe whatever isn't right with the fuel pump power is also telling the injectors not to open??? When we spray carb cleaner in it it runs until we stop.

 

If you have power to the fuel pump all the time , you should be able to confirm that by checking as close to the tank as possible that that power is getting there. Make sure the ground for the pump is good and clean. If those two items are good , the fuel pump is with a problem. The fuel pump relay gets a signal from the computer to operate the relay that operates the pump. It is supposed to operate for 1-2 seconds when you first turn the key on. Does it do that? (make sure the inertia switch is good)
If this helps any, the injectors should have power going to them any time the key is on. The computer provides the ground at the right time for the injectors to operate.
The computer has to get a RPM signal for the fuel relay to stay energized. That signal is generated by a pick-up coil in the distributor then on to an ignition module .