Truck has good battery but can't get it to turn over?

[White70C20]

Hello all,
I am having another electrical problem with my green '70 C20. It has had an issue with not starting before, but I have always been able to remedy it fairly quickly. Not anymore.

Last Sunday I went out for a drive, I had to jumpstart it (none of my usual remedies worked). I noticed that my aftermarket tachometer was bouncing around at low RPMs and not giving me a correct reading. I also noticed that it was misfiring. When at a stop I noticed I had no lights either. then it died. When I tried to restart it nothing happened, no click, nothing except the tachometer needle would bounce when I turned the key back to OFF.

I got it back to the college and left it alone until today. A friend of mine made a very convincing diagnosis of a sticking starter solenoid. He said that the solenoid sticking could cause a short that could affect the whole electrical system (is he full of BS?) He said to replace the solenoid. It was only $15 so I thought it couldn't do any harm. Tonight I replaced the solenoid and nothing changed. I got everything hooked back up it still wouldn't start. I fixed a worn, frayed battery cable and now I have all my lights back, but it didn't help the starting.

Sorry for the long post. Does anyone have any suggestions? Thanks!

[BADAZ chevy guy]

I'd start by replacing the battery cable if they're starting to fray. Make sure you have a good ground connection to the body and the frame.

[ClemsonChevy]

Have you had the battery checked? Check for good clean connections at both ends of both cables and smaller wires that go to starter? Check for 12v to the S terminal on starter when key is in start position (will need two people). Hook some wire to the S terminal on the starter and touch it to the + battery terminal and see if it will turn over. If so, it's a problem at the switch or wiring to starter. If not, starter is bad.

[White70C20]

Thanks!
The battery is only 4 months old. I will go out and check the connections again tomorrow. I might be able to get a friend to help me check the voltage at the starter. One problem I faced tonight and will continue to face is that someone put full headers on the truck before I got it. This makes it hard to access the starter from the engine compartment. It's a little easier underneath the truck, but not much.

[BlacklandCamper]

I would say engine ground first, but also check your alternator just to make sure it is still ok. Are you using an internally regulated, or externally regulated alternator? Is your tach power source connected directly to your ignition switch? The fact that it still flickers when you turn the key could show that the switch is still transferring power.

I have yet to see a stuck solenoid cause a large enough issue to affect power to the rest of the harness with out causing major wiring damage in the process. The solenoid circuit is typically independent of the rest of the electrics with the exception of chassis ground, and switched power at the ignition.

Chase your engine ground straps, and inspect the wires and connections from the battery, to the ignition switch, to the starter. If nothing is amiss, inspect the wiring at the fuse block, and then get into swapping hard parts.

Unless your distributor clamp gave up, and your ignition timing is way off.....

[White70C20]

Thanks!
I had the alternator checked back in January. It was fine at that point.
I will check the engine ground tomorrow (where is that located exactly?).
I'm also going to go back and check the two small wires at the solenoid (again).

[BlacklandCamper]

There should be a ground strap on the back of each head, going to the firewall.

I have found the easiest way to test a stuck solenoid is to hit it with a piece of wood. Not too hard, just give a few good raps. I have found a broom handle is usually the best tool for the job. If it starts after, yep, it was stuck.

[White70C20]

Is it possible that a brand new solenoid could be stuck? (I don't think so.)

I'll check the ground straps at the back of each head and look for any other wires that look like they could be causing a problem.

I'm going to try to eliminate everything else before the fuse panel first. The wiring in and around the fuse panel is so much of a rat's nest full of several owners' own electrical repairs. There are several wires just stuck in next to a fuse to complete a circuit for things that I'm not even sure where they go or what they do. It would take a guy that's good with electricity (not me) quite a while to sort out that mess.

[jdw]

Headers get a lot hotter than the stock manifolds. Check spark plug wires, starter, anything close to em.

[cdowns]

when checking wire connections it is best to take apart clean surfaces and reconnect them //the staring at them sternly and doin nothin accomplishes nuttin

[71swb4x4]

Lots of great advice in this thread, but the same answer from you; it's new, or it's a couple months old, does not mean it works.

When I read your first post I see a dead battery, or a bad connection.

Start with the basics.
Check the voltage at the battery, is it charged now?
If it is charged check connections. Positive and negative at the battery, pull them, make sure wires look good, clean up connections, and reattach. Same with the positive to the battery, and the negative going to the block. Then make sure you have a good ground going from the block to the cab.
If that doesn't fix your problem remove the battery and have it tested, since you are having things tested take the alternator in at the same time.

Work through the easy things and report back.

[BlacklandCamper]

An old trick I've learned when dealing with starter issues on SBC engines with headers, is to install a Fud solinoid on the fender well and wire it inline to your starter. That negates any hard start issues due to hot starter.

Just because the solenoid is new, doe not mean it is free from issues.
What brand is it?

[michael bustamante]

Yup you might have internal corrosion inside one or both battery cables. Also. Are you running a hei andwhat kind of alt?

[White70C20]

Lots of great ideas guys!
Yes, I will clean up all the connections.

Also, the new solenoid is a BWD, that's the only kind they had.

Yes, I am running HEI and I'm not sure what kind of alternator I have.

I was working on my truck in the shop here at college. They told me to leave at 10:00 last night so I had to push it outside into the parking lot. I'll have to go do some poking around and report back.

[GASoline71]

There is an external voltage regulator on the core support right next to the drivers side headlight. Looks like a little black box with 4 wires coming out of it whith a connector. Have it checked to make sure it's not bad. If it's bad, they cost about $15 to $20 bucks.

Gary

[White70C20]

Just a quick question:

What would be wrong with bypassing the fuse panel and wiring harness and running two new wires from the starter solenoid to the ignition switch? I would use fusible links that would act as the fuse in the fuse panel.

Aside from not being very professional and looking messy, I can't really see any major problems with this solution.

The reason for this is that the wiring harness on my green '70 is atrocious. A couple friends and I traced several wires in the engine compartment and found that most of them had been cut and spliced with different colors of wire. It makes reading the wiring diagrams very difficult.
Plus, I took the ignition switch out and saw that a couple of wires that the diagram showed weren't even there, and most of the ones that were there weren't the right colors.

I think a simple solution would just be to bypass the entire harness. Yes, I'll be adding to the clutter under the dash, but at least I'll know I have a solid connection to the starter.

[Rockit]

The first thing I would do is get the battery load tested. So many times I see cars having electrical problems and as a last resort get the battery test. Some brands of battery's are not to good even when new. If a plate in side the battery breaks or touches the plate next to it, it's still fully charged but the voltage is now messed up and causes all kinds electrical problems. My son has had this problem in his early Bronco that he does not drive much. Got his never start battery warranted 3 to 4 times and put maybe 500 miles on it in that time.

[White70C20]

The battery is fine.

[bigmac73]

Originally Posted by White70C20

Lots of great ideas guys!
Yes, I will clean up all the connections.

Also, the new solenoid is a BWD, that's the only kind they had.

Yes, I am running HEI and I'm not sure what kind of alternator I have.

I was working on my truck in the shop here at college. They told me to leave at 10:00 last night so I had to push it outside into the parking lot. I'll have to go do some poking around and report back.

Is this a hobby/repair shop for students to use, or is a teaching shop? I would think there would be somebody who works there to help you out, and instruct along the way????

[White70C20]

It's the shop where we have class during the week, but on the weekends (when none of the professors are there) they open it up to students who have classwork and/or their own vehicle to work on. Since there are no professors around, if you get stuck, you have to ask another classmate for help and hope that they either know how to do what you're doing or are just willing to help you mess with stuff in hopes that things will work.

It's not nearly as sketchy as it sounds. This is a very professional school.

[brad_man_72]

If your truck will start from being jumped from another car your battery is dead for one reason or another. Bad voltage regulator (if your alternator had to charge a dead/bad battery it can burn up the voltage regulator causing a key off short). New parts including batteries can be bad.

[ClemsonChevy]

IF you've tried turning the key to start and get NO voltage at the S terminal on the starter AND you've tried cleaning that connection, the connector to the ignition switch AND the firewall connector, then I would say go for it.

Originally Posted by White70C20

Just a quick question:

What would be wrong with bypassing the fuse panel and wiring harness and running two new wires from the starter solenoid to the ignition switch? I would use fusible links that would act as the fuse in the fuse panel.

I think a simple solution would just be to bypass the entire harness. Yes, I'll be adding to the clutter under the dash, but at least I'll know I have a solid connection to the starter.

[VetteVet]

Originally Posted by White70C20

Is it possible that a brand new solenoid could be stuck? (I don't think so.)

I'll check the ground straps at the back of each head and look for any other wires that look like they could be causing a problem.

I'm going to try to eliminate everything else before the fuse panel first. The wiring in and around the fuse panel is so much of a rat's nest full of several owners' own electrical repairs. There are several wires just stuck in next to a fuse to complete a circuit for things that I'm not even sure where they go or what they do. It would take a guy that's good with electricity (not me) quite a while to sort out that mess.

The starter solenoid only has two functions. To engage the starter gear with the engine flywheel, and to connect power to the starter fields to turn the starter motor. If it is stuck it will cause the starter to continue to turn over, or after the engine starts it will continue to turn the starter motor through the engine/starter gear engagement. It will make a loud grinding noise either way.

If you run a wire directly from the key switch to the S terminal on the starter it will bypass the safety feature of the neutral start switch. It might start in gear and cause damage or injury.

The purple starter wire runs from the key switch to the neutral switch, then to the firewall block, and on to the solenoid where it connects to the S terminal on the starter. You could jump across the NSS connector to test the switch and if you still don't get voltage at the S terminal you might have to take the firewall block apart and clean the connectors in it.

Be sure to put the trans in neutral and block the wheels in case it starts.

[trukman1]

Very common problem is ground strap from starter to solenoid loses contact. Looks like a small, flat copper bar (its actually two) running vertically. Giving it a couple "raps" with a large, long handled screwdriver often works (don't try to kill it!) Its also easy and free to try. Have had this happen too many times to count.

[White70C20]

Thanks for the input guys.

Ok, I went ahead and put in a new wire from the solenoid to the brand new key switch. I also ran a new wire from the solenoid to the HEI coil on the distributor. It started up and ran ok for a while. When I came back later to drive it around it did its same stuff again. Nothing would happen when I turned the key.

Today, I tried twice to start it. I would jumpstart it off my car and then check and see if the lights/turnsignals worked. They would at first, but after 10-15 sec. they would go out. Then within a minute the engine would stall.

This evening I went out and cleaned up all the ground connections (the ground cable and block-to-frame cable). I looked and saw that neither of the ground straps that go from the firewall to the cylinder heads had been connected for years, so obviously it had been running fine without them.

I got good contact at the grounds. The battery read 11.7 V (I know that's not enough to start the engine, but at least it should attempt to crank over). Nothing! Not even a click or growl from the starter.

One thing I found unique was that if I turned on the turn signals they worked fine, but if I also turned on the headlights, the turn signals would quit. After messing around with different variations of this for a few minutes the turn signals decided to quit altogether. At this point it was getting dark so I called it a night. This issue has me baffled.

However, another friend of mine had the idea that maybe the HEI coil on the distributor could be bad. Does this seem logical? I don't know.