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TBI won't fire up

My truck was a diesel, so it has threaded/reinforced bolt holes on the passenger side of the firewall for maybe an oil(fuel, dummy)/water separator? I'm pretty sure my coil bolted right there without needing to make a plate to adapt the bolt pattern. I like it there, it's out of the way but easily accessed. Not like it's ever failed, but if it does, or for troubleshooting, real easy.
 
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40+ years of wrenching. I had found less than a 1 hand full of bad coils on single coil system.
Coil on plug and waste fire systems have been more, but not as many as you think.
 
Wes Harden said:
40+ years of wrenching. I had found less than a 1 hand full of bad coils on single coil system.
Coil on plug and waste fire systems have been more, but not as many as you think.
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Same here, been turning wrenches a very long time now.
I can count on one hand how many single coils that have gone bad.
One of them was in Moab on the white rim trail, 70 miles out. $2K Tow bill, 30 minute diagnostic $40 repair.:doah:
 
Wes Harden said:
Pro tip get the old cap complete outta your way, leave the rotor on. put engine on #1 tdc compression stroke. Mark which cylinder the rotor is pointing to.
Loosen hold down and slide it away from dist. You can turn the dist body all you want, spray a little light penetrate oil at the seam of the dist and intake turn the body a few times, this helps wash any oil scum build up away. Start to lift the dist body slowly, as you do you'll see the rotor turn, at @ 1/2" the drive tang will come out the slot on the oil pump and little bit after that the gears will disengage. Mark where the rotor is pointing at this time, this where you want your pointing when you begin to install the new dist. As it slides in the rotor should turn back to original spot you marked before you loosened the hold down. Some times the oil pump drive tang won't slot in right away, a little wiggling of the dist body and rotor, with out loosing the gear mesh, will get to go. Make sure the dist body is fully seated, rotor is pointing where you marked it, and put the hold down back snug but not tight. When ready to time you need to disconnect the timing connector, Spec is 0° I like 2-4°, but if the knock sensor circuit malfunctioning 0° is best. tighen the hold down plug timing bypass back in. Good to go
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Thanks! Would it not also make sense to mark the orientation of the wire connections on the cap to get the timing close? What is the factory orientation of the module connectors, toward the front of the vehicle?

Oh, is the timing connector a single pin deal put in the harness for just this purpose, leading to one of the 4 on the 4-pin? I may have to add that if my current harness doesn't have it.

EDIT: Found the answer to that last question one up thread:
1706920646512.png
 
Found this pic online. Does it look right, connectors to the back driver's side area? I assume it's not actually critical that the cylinders be exactly the way shown as long as the order is correct, right?

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That is where I like to put it. I you don't put it there the factory wires will not fit well. Aftermarket wire is anybodies guess. When ask earlier about the ICM plug clocking I couldn't remember but towards the back was what I wanted to say. If you match the picture you will be in good shape
 
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I made a bracket to mount my coil to the firewall close to the distributor. You may want to check to see if your distributor is not too long. I had a problem with my aftermarket distributor being too long, and I had to shim it up some. I also had to use the stock distributor gear off my old one because the Chines aftermarket distributor gear was not manufactured correctly, and was getting chewed up. Another thing I did was make a ground wire for the control module by getting a control mounting screw that was a little longer than the stock one. I then attached a ground wire to the under side of the distributor where the screw stuck out at the bottom. Control modules are poorly grounded from the factory, which causes cheap Chines control modules to burn up.
 
Sometimes if the heads have been milled a time or 2, the intake sits low, and need a second gasket. That pretty bad experience with the aftermarket dist
 
Wes Harden said:
Sometimes if the heads have been milled a time or 2, the intake sits low, and need a second gasket. That pretty bad experience with the aftermarket dist
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My engine is a brand new crate engine that has never been rebuilt. I could see where a rebuilt engine would have problems in a few areas because of head milling.
 
Hopefully the DUI distributor is not just relabeled Chinese junk, but you never know.
 
Is there any reason I can't orient the connectors differently so long as I attach the plug wires properly? It might make more sense for me to have them front/passenger because of the way my harness is.
 
Thanks. Is there any reason it really matters though as long as it's timed properly with the correct firing order?
 
I'm looking for the harness wiring diagram for our trucks. I found this one, which might be right, but it says it's for a van. Does it apply? I thought I was expecting to see two ECM related relays, but this only has the fuel pump as far as I can tell. My current harness taps the coil (ign +12) power for some purpose which I haven't traced yet...

https://www.ih8mud.com/tech/tbi/wireTBI-1990a.gif
wireTBI-1990a.gif
 
Wes Harden said:
yeah that is a P van, read step van, bread van, ups type van.
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I'd love to have the equivalent diagram for our trucks. What is different with the vans? And I wonder why GM would bother wiring stuff up differently for different vehicles with the same engine.
 
I couldn't say w/o seeing them all side by side. I just add 89-92 F-G body to gallery, still looking for ours I have it somewhere in my literature, from back in the day.
 
Mastiff said:
I'd love to have the equivalent diagram for our trucks. What is different with the vans? And I wonder why GM would bother wiring stuff up differently for different vehicles with the same engine.
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You mean like the ones on CK5?

1990 GM Technical Manuals

1990 GM Technical Manuals Number Title ST-350-90 1990 GM RV & P Light Truck Wiring Manual ST-502-90SB 1990 Service Bulletin Supplement X-9032 1990 GMC RVGP Light Duty Truck Service Manual X-9037 1990 GMC Light Duty Truck Unit Repair Manual
ck5.com ck5.com

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