Starter dragging;stays on when key shut off, wires hot, frying solenoids,arching HELP [Archive] - FSB Forums

: Starter dragging;stays on when key shut off, wires hot, frying solenoids,arching HELP


stevensrat
12-13-2009, 11:15 AM
I have a 1985 Bronco with a 4 speed manual and the inline 6 cylinder 300 engine. I bought it 2 months ago and finally dropped it off at the mechanics because I gave up. But my mechanic can't figure out whats wrong. PLEASE HELP.

New Parts (last 2 months):
distributor cap, plugs+wires, starter, solenoid, battery cables and I bought a new high crank battery, ignition switch.

The starter will continue to run after the key is in the shut off mode. Also the cables get extreemly hot. So hot that one time I jumped it with my car and the rubber coating on the jumper cables melted. It was also arching. My mechanic fixed the arching and supposedly checked all the grounds. He says that it's "frying solenoids"....Also we got to a point where it wouldn't start at all even if we jumped the solenoid. I took the starter out and had it bench tested and it started fine. However, I don't believe the bench tester had a ammeter. My mechanic is talking about replacing the wiring harness now and I don't think thats nessesary. Can someone please give me some ideas I can give to my mechanic on Monday morning?
Also just a shot in the dark, but I live in Oakland, ME...anyone know of a reliable mechanic I can start going to around here.

tbo84bronco
12-13-2009, 11:21 AM
If the starter continues to run after you start your truck then the starter is bad thats what happened on mine. but a buddy of mine had a similiar problem and after he would start it he would barely turn the ignition back and it would stop dont no why. i would double check and make sure everything is hooked up right on the solenoid
taylor

El Kabong
12-13-2009, 01:18 PM
It sounds like once the solenoid is energized, it stays energized. I wonder if wiring is crossed up so that 12v from the starter side of the solenoid or the "I" terminal is applied to the "S" terminal. Or the solenoid might be bad. Does an 85 still use the 4 post solenoid or is it the newer 3 post type? (Pics below)

Try this test:
-Leave a battery cable loose enough to remove easily, but tight enough to make good contact. Be ready to pull the cable if it keeps cranking. Have gloves or rags ready to keep from being burned by the hot cable if you have to remove it.

-Disconnect all of the small wires from the little "I" & "S" terminals on the solenoid.

-Jump from hot to the "S" terminal to crank it for a couple of seconds. Let off & see if it stops. If it keeps cranking pull the battery cable quickly before it has a chance to heat up & burn you.

Results:
-If it keeps cranking with all the little wires removed, replace the solenoid. It's hanging up internally. You said it was new, but sometimes they're bad right out of the box.

-If it stops cranking with the little wires removed, you have an issue with the little wires. Measure voltage from the little wires. You should only have 12v to the "S" terminal when the key is in the "Start" position. Somehow there's 12v getting to the "S" terminal once you start cranking it, even after you let off. That sounds like it might be getting a feed from the "I" terminal or the large cable to the starter. Are there any shorts between those wires?


4 post solenoid. This is from a 69. If you look close you can see the little "S & "I" cast in the plastic. The large cable on the left comes from the positive post on the battery. The multiple small wires that connect to the same terminal as the positive cable provide 12v to several other components. The large cable on the right runs to the starter. The small wire on the left "S" terminal brings 12v from the ignition switch when the key is in the start position. The small wire on the right "I" terminal sends a full 12v to the coil while trying to start the truck. If "S" & "I" were connected together through a short in the wires, the starter would continue to run after the key is turned off.
http://www.supermotors.net/getfile/534806/fullsize/100_0012.jpg%20alt=

3 post solenoid. This is from a 90. The large cable on the right comes from the positive post on the battery. The multiple small wires that connect to the same terminal as the positive cable provide 12v to several other components. The large cable on the left runs to the starter. The small wire at the little top "S" terminal brings 12v from the ignition switch when the key is in the start position. Note that there is only one wire connected to the large terminal for the starter cable on the left.
http://www.supermotors.net/getfile/514482/fullsize/100_9803.jpg%20alt=

stevensrat
12-18-2009, 12:06 AM
I think it's fixed...I over looked a pretty simple step. The previous owner grounded the battery to the frame. My mechanic grounded it to the engine bloack and so far so good.
Thanks for everyones help.

bronco1
12-19-2009, 11:11 AM
Make sure there is also a good ground to frame and body.

Bronco3006
12-21-2009, 03:13 PM
check all your grounds, engine/frame to body, negative battery cable is snug on a starter bolt and free of oil.