ICM or timing?

[wilsbronco]

Alright, this is part 2 of my starting woes. The engine is an 86 era 5.0 fuel injected according to all the parts that fit it (not original to truck). Two weeks ago, it refused to start up. Looked at the big 3 -- air, fuel, spark. Air and fuel okay, no spark at the coil. Replaced the coil, still nothing. Found that there was a rubber splice from the tach to the coil and ICM that didn't have continuity, cut it out, respliced and it fired up. Worked well for about a day and a half. Flaps tells me the rubber splice probably had a resister inside (the side of the rubber had a resister/zigzag symbol on it and P-3, no other markings). There's no resister shown on the electrical diagrams for this part of the circuit, so while I'm sure I ought to replace it, I'm not sure what size it should be.

Anyway, after more fighting with it today, I get a spark at the coil IF I pull of the SPOUT connector. It still won't start (spark looks a little weak perhaps), but it at least sparks and sounds like it's trying. Haynes troubleshooting said to check the voltage there, I did, it was within specs. According to Haynes, the test meant that, by default, the problem must be with the ICM. I'm wondering if timing isn't a possibility instead since the book also said to pull off the SPOUT short when you do the timing? (rotor was replaced, I tried replacing pickup coil but the distributor won the first battle, rotor ~may~ have been moved inadvertedly during battle), or still a possible wiring issue? If it's the ICM, okay, I just don't want to get the distributor moved to get to that blasted bottom ***** just to have it still not start.

 

[Seabronc]

The Bronco uses resistive wire not a resistor, see attached diagram. The splice you were looking at was probably at one end or the other of the resistive wire. The SPOUT connector being removed allows the ignition to run on it's own with the default timing you set up, the reason for the instructions to disable it. If you don't the computer controls when to fire the plugs. Follow the initial timing instructions first.

Good luck,

>-

 

[Seabronc]

The Bronco uses resistive wire not a resistor, see attached diagram. The splice you were looking at was probably at one end or the other of the resistive wire. The SPOUT connector being removed allows the ignition to run on it's own with the default timing you set up, the reason for the instructions to disable it. If you don't the computer controls when to fire the plugs. Follow the initial timing instructions first.
Good luck,

>-

OOPS! forgot the diagram

 

[wilsbronco]

OOPS! forgot the diagram

Thanks, I had that page, but the resistor/resistive wiring shown on the diagram goes to pin 3 and the battery side of the coil. The thing I cut out went to pin 2 and the TACH side of the coil. Does page 98, "to tachometer", show any resistor or resistive wiring? If it's just going to the tachometer on the dash, that hasn't worked since I got the truck so it shouldn't really matter if I have the resister or not. The other choice shown is page 60 going to EEC. You gave me p.58 and 59 before so I'm not sure. (fyi, I ~do~ have an EVT manual, but it's for an 81 since my base truck is an 81 ... I guess I ought to pick up an 86 as well since that seems to be what my engine is).

Thanks for the help!

 

[wilsbronco]

Thanks to Miesk's website I found the page with the mysterious resistor ... p. 60 of the 86 EVTM ... 22k ... and it goes to the electronic control assembly. Looks like something that got added in between 85 and 86. I'm going to go get something suitable and see if I get lucky ... just hoping nothing got fried while it wasn't there, although it doesn't seem that big.