77 c20 electrical issues.

[Troglodyte]

My recently acquired 77 c20 (454) is giving me headaches. When I first bought it, it wouldn't start. First thought was the starter because it wouldn't even try to turn over even while being jumped. After some tinkering we figured it wasn't the starter because it wouldn't take a charge. So we swapped the cables and she started. Solved right? Wrong. Next day same story. Wouldn't start, battery won't charge. So new battery maybe? Wrong. Bought a battery and when I connected the negative it sparked and something shorted and smoked behind the block. Not sure what and I don't want to connect it again to see.

Any thoughts? I can't figure out what was smoking or why.

[anubisani]

Originally Posted by Troglodyte

My recently acquired 77 c20 (454) is giving me headaches. When I first bought it, it wouldn't start. First thought was the starter because it wouldn't even try to turn over even while being jumped. After some tinkering we figured it wasn't the starter because it wouldn't take a charge. So we swapped the cables and she started. Solved right? Wrong. Next day same story. Wouldn't start, battery won't charge. So new battery maybe? Wrong. Bought a battery and when I connected the negative it sparked and something shorted and smoked behind the block. Not sure what and I don't want to connect it again to see.

Any thoughts? I can't figure out what was smoking or why.

check all the cables at the starter make sure they are not touching also check all grounds make sure the are clean and well grounded but it does sound like u have a problem at the starter if not the starter itself.

[Troglodyte]

The starter seems to be good. When she feels like starting the starter work great. I believe the starter is just not getting enough power. It will click but wont turn over the engine. All wiring appears good. Nothing frayed or touching. When i put new cables on I cleaned the grounds and connections so its not that. Got the new battery in, not sure what was going on earlier. But she still wont turn. The starter tries but just cant.
Posted via Mobile Device

[mrolds88]

First, check your grounds. One should be on the front of the block/alternator bracket, another backside of the passenger head. Also check the wiring to and from the wire block in the middle of the firewall. You had sparks and smoke. Something was hot. There is at least one fusible link on that block. Could have fried it. And check the ignition switch itself.

[Troglodyte]

First, check your grounds. One should be on the front of the block/alternator bracket, another backside of the passenger head. Also check the wiring to and from the wire block in the middle of the firewall. You had sparks and smoke. Something was hot. There is at least one fusible link on that block. Could have fried it. And check the ignition switch itself.

All wiring appears good. Nothing frayed or touching

Checked it all. I'm clueless. she started no problem today multiple times

[mrolds88]

Ok one last thing I can think of. Behind the phenolic cap on the end of the solenoid there is a copper disc. That sometimes burns and will make starting hit and miss. Two cures for that. First is to clean the front and replace. If its iffy, the second route would be to turn it around. Gives it a fresh side.

[Troglodyte]

Could you provide me with pictures?

[mrolds88]

Sorry for borrowing the pic. I have the piece I was referring to circled in yellow up above the master cylinder

[Troglodyte]

Haven't had a problem starting the truck since. No idea what was wrong or why it magically fixed itself.

[nheller76]

Ive just had issues with this too, the wire that mrolds88 told u to clean should have a fuse in it near the end twords the starter. I know mine was blown and it would work half the time and then stop then magically fix it self for a bit. U need that there because it protects your system form being overloaded, you can go to a parts store and get another end you can splice on. Its not fun but it should help.

[hotrod_991]

i had same issue with an 86 c10 i was working on. it would spark and smoke misteriously behind the block and by the trans. It was a ground issue. if you do not have a solid body, chassis and engine ground. my truck was basically searching for ground anywere is could find. i cleaned all cables and fixed the grounds.