With this engine being half frankenstiened together. I really have no idea what’s actually in the distributor. I’ve had no reaosn yet to actually take the cap off, it looks similar to an hei cap but has plugs all across the top instead of the coil, so I assume it’s the correct one, and no one mentioned it being wrong yet. But if it is all ecm controlled than that shot down the idea of the advance being a problem.
@AuroraGirl had mentioned ecm problems and I’m not computer enough on vehicles to dive into that. My oil pressure gauge is pegged all the way to the right (3 o clock position) is this the gauge or the sensor? It’s been like that sense before I got it but I checked the oil and it’s a quart low so I’d like my gauge to work now since I don’t daily this truck much anymore.
This truck has more drama than Days of Our Lives and As the World Turns put together.
First, the oil pressure is probably but not definitely the sensor. If you have a multimeter you can test it pretty easily. The sensor should be close to your oil filter. The one that is right under and behind the distributor is a switch and is not attached to your gauge... but in your case, I guess that may not be a definite answer.
This is what mine read when it went bad and pegged out the gauge.
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Next, pulling the distributor cap and checking it and the rotor are pretty basic and as long as you have been fighting this I would have figured you would have done this by now.
You do not however have to pull the distributor to know what type it is. The '87 TBI should NOT have a vacuum advance connection. There should be two sets of wires plugging into the Ignition Control Module. The plugs will be at the base of the distributor cap, pointing at the firewall more or less towards the steering wheel.
You can see part of the ICM and one plug in this pic:
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By the way, that shiny silver thing screwed into the shiny brass thing underneath the distributor is the Oil Pressure Switch...or at least it SHOULD be.
I haven't been following this one very closely since it has gone on for so long but I will share with you a little saying from the motorcycling world. "90 percent of carburetor problems are electrical" That is probably more relevant to the older, carbureted bikes but it may have some value when troubleshooting this truck.
Your ICM is an easy and cheap part to replace. The MAP is supposed to communicate with the ICM via the ECM...
If you need to check your timing you will have to know the super secret location of The Plug. On my '87 it is close to the steering column, below the brake booster. It is a single wire plug and when you unplug it (make sure the engine is NOT running during the plug/unplug) the timing should be at 0 degrees. With it plugged back in and the engine started it will be advanced significantly.
Sorry for the blurry pic:
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