71 C20 starting problem

[Bruser]

I need some help with a starting problem with my 71 C20. After I got it back from the body shop it won't crank. Here's a background and list of things I have already tried. History; last May I started tear down to prepare for painting. Everything in the dash came out or loose. Truck was driven daily before this and never had any problems running or starting. It has been converted to Electronic Ignition but other than that it is a stock 350 (a 78 year not the original 71 year). I have replaced the battery, taken the starter to auto electric shop for testing (passed), new battery cables positive and negative, replaced the fuse and holder that is close to the battery coming off junction on inner fender area. Engine is not locked up, I have turned it over at the flywheel and taken all plugs out to reduce compression. Symptoms; engaging starter at key (lock is out) the solenoid clicks and throws starter gear into flywheel enough to barely begin to turn engine over then stops. If I jump the solenoid with a screw driver it turns over like a champ. What gives? Could it be the key switch? The ammeter is not hooked up yet, is this necessary for the circuit. Fusable links?

[Longhorn 70]

I had a weak solenoid that did the same thing. Pulled it of and replaced with a new Autozone HP solenoid. No more problems.
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[c10monkey]

You said the it cranked great when you jumped it with a screw driver.....

I would run a wire from the small terminal to the battery... just to test... but if it works good then you know that there is a problem in the circuit.

But I would unplug the ignition switch and make sure the connections are clean and making good contact.

[VetteVet]

I agree with c10Monkey that you have a high resistance in the purple wire from the key switch. Jumping the small terminal to the large one confirmed that. You might run the wire from the battery and if it works then jump the purple wires at the neutral start switch and try it. The firewall block is another place you could get a poor connection.

forget the ammeter, it has nothing to do with starting, ignition , or charging.

[Bruser]

Thanks for the suggestions. I was hoping I could get a consensus on the possible solution. I did pull the neutral safety switch off the column and jumped (bypassed) it. A guy at the NAPA store suggested that. I will try the idea of checking the connections at the switch and if that doesn't work I will bypass the switch altogether (hot-wire) it. I have just never heard of a bad switch on a car or truck of this age. In regards to your mention of a firewall connection to check, do you mean the fuse box?

[VetteVet]

Originally Posted by Bruser

Thanks for the suggestions. I was hoping I could get a consensus on the possible solution. I did pull the neutral safety switch off the column and jumped (bypassed) it. A guy at the NAPA store suggested that. I will try the idea of checking the connections at the switch and if that doesn't work I will bypass the switch altogether (hot-wire) it. I have just never heard of a bad switch on a car or truck of this age. In regards to your mention of a firewall connection to check, do you mean the fuse box?

No there is a connection block on the firewall beside the master cylinder that comes apart when you remove the center bolt and it is the connector for all the engine to cab wires. The purple wire is right on the top.

[ole86chebby]

someone may have already said something, or you may have ruled it out already.

but i had a similar problem with my 86...come to find out a wire had broken off one of the terminals on the solenoid...i put a new eye on the wire and it started right up.

hope you find out what it is.

[Bruser]

Thanks for all the help guys. I had a dry weekend day to spend time on it today (Washington State). After trying your suggestions and having no luck I focused on the switch. As I mentioned I had the key lock cylinder out. I wondered if there was any chance of an incomplete circuit with the key switch cylinder out. I pushed the little lock pin down on the switch barrel as I rotated the slot in the switch housing with a screw driver and problem solved. I put the cylinder in and turns over and starts great. Thanks again for the input, hopefully my problem and solution will help someone else in the future.

[Longhorn 70]

WOW here we were thinking electrical and it was basically mechanical. Good find. Glad you got it going.