living_4kicks Posted October 29, 2017 Report Share Posted October 29, 2017 I was driving to work felt the truck lack then was running rough. Got home it would run would just be rough. As it was at idle I put a timing gun on it just to see where things weren't firing. Both coils were sending spark all four plugs were getting spark on the exshaut side, none were getting spark on the ignition side. I then took the cap off, put a older cap(that still worked) on. Made sure the firing order and wires didn't get crossed then the truck wouldn't start at all. Switch the caps back, making sure to keep all wires the same. Decided it was the cap I could switch intake and exshaut. Then the intake would fire and exshaut wouldn't. Well that didn't work. Truck still won't run. Tested spark and one. Coil stopped sending spark. Put a multimeter on and didn't have power to intake, but not getting a full 12V to the exshaut. Not really sure where to go from there. I don't know where the relay is. Could it be a ground issue. Thought? 1 Quote Link to comment
datzenmike Posted October 29, 2017 Report Share Posted October 29, 2017 The intake coil gets power directly for the ignition switch. For some reason the exhaust coil gets it's power through the fuse box and from the ignition switch. The high tension leads can easily get swapped on the way to the distributor cap. Doesan't really matter if the intake coil is firing the exhaust side as both coils fire together. I would start be replacing the first fuse on the far left side of the fuse box (10 amp) This is the fuse for the exhaust side coil. 2 Quote Link to comment
living_4kicks Posted November 2, 2017 Author Report Share Posted November 2, 2017 Fuse is good. I had to run a ground wire from the intake coil to the battery to get power to that coil. 1 Quote Link to comment
datzenmike Posted November 2, 2017 Report Share Posted November 2, 2017 Coils are grounded through the module in the distributor. You mean a jumper to the positive battery terminal. REPLACE the fuse. Never trust a fuse on looks alone. Or swap with another known good 10 amp fuse If still nothing pull the fuse out and us a tester on the two terminals inside the box. One side will have to have 12 volts as this comes directly from the ignition switch. It's the White/Blue stripe wire on the switch. Should show 121 volts in the ON and START positions. 1 Quote Link to comment
living_4kicks Posted November 2, 2017 Author Report Share Posted November 2, 2017 Yeah, I swapped the fuse. No. I ran a wire from the battery to the ground on the coil. 1 Quote Link to comment
datzenmike Posted November 2, 2017 Report Share Posted November 2, 2017 You mean the + positive side of the coil. The negative side of the coil is turned on and off to ground by the module in the distributor. 1 Quote Link to comment
living_4kicks Posted November 2, 2017 Author Report Share Posted November 2, 2017 No, I have a wire going from the negative coil post to the negative side of the battery. This is the only way that coil has power. My problem is not consistent. So that tells me grounding issues. I know it doesn't make since. Let's back up and make sure I have the right wires going to the right place. White with blue strip is the negative and brown is the positive on the intake coil. 1 Quote Link to comment
Crashtd420 Posted November 2, 2017 Report Share Posted November 2, 2017 No, I have a wire going from the negative coil post to the negative side of the battery. This is the only way that coil has power. My problem is not consistent. So that tells me grounding issues. I know it doesn't make since. Let's back up and make sure I have the right wires going to the right place. White with blue strip is the negative and brown is the positive on the intake coil. Not sure about the colors but what you say doesn't make sense.... The negative should only be from the distributor like mike said.... if you grounded the negative side of the coil then technically wouldn't it be constantly firing...... the negative from the distributor is the trigger to make the spark.... power should be constant not the ground.... Maybe you should check ground in general... body to motor... even reground the body of the distributor.... 1 Quote Link to comment
datzenmike Posted November 2, 2017 Report Share Posted November 2, 2017 The flow of power is from positive to negative (ground) like this... Battery + to... Ignition switch... to + intake coil and fuse box to... the + exhaust coil Intake and exhaust coils - terminals to... the distributor which connects and opens a path to ground to fire the coils. I have the '84 FSM and can try to identify the coil wiring.. 1 Quote Link to comment
living_4kicks Posted November 3, 2017 Author Report Share Posted November 3, 2017 Found the problem, Both coils are firing now. The terminal block from the distributor to the coils had a bad wire. Ran a new one both coils are working now. Thanks for the help all 2 Quote Link to comment
datzenmike Posted November 3, 2017 Report Share Posted November 3, 2017 :thumbup: 1 Quote Link to comment
living_4kicks Posted November 4, 2017 Author Report Share Posted November 4, 2017 So have another small issue. Got spark turned truck over and it wasn't running good. Pulled the plugs and #1 intake and exshaut spark plug was broke. The ground rod was broke off. Any ideas as to why or how it could have happened. 1 Quote Link to comment
datzenmike Posted November 4, 2017 Report Share Posted November 4, 2017 Most likely the wrong spark plug reach. Should be BPR6ES intake and BPR5ES exhaust. The E is 19mm of plug reach. Damaged piston or valve part or foreign object found it's way into cylinder. Pre ignition can also break plugs. This is the least likely unless this happened before the last problem. 1 Quote Link to comment
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