Bad Grounds

[69CamaroRacer]

What is the best way to test for a bad ground?? I have constant electrical problems with my 69 camaro. It is usuly start/no start problems ... It will run fine and then I will go to start and nothing..

[paul67]

That sounds like the starter sol getting hot.

[David Pozzi]

Start at the battery and check that the cables are clean and tight, then check that the battery ground cable is attached to a clean area on the block
Check the neutral safety switch on the steering column.

[ls427ss]

do a voltage drop test between the neg cable @ the battery, and the block.

[Bad Bowtie]

Check the neutral safety switch on the steering column.

This gets my vote
BB

[69CamaroRacer]

Nutural safty has been removed from shifter assembly...

[vintageracer]

Do a voltage drop test on the wiring harness as previously advised. I have seen a drop of 4 volts from the battery to the firewall plug in OLD factory front engine wiring harness's on Chevelles/Camaros in the past. This voltage drop was from the + termimal junction on the radiator support by the battery to the firewall wiring harness plug/connection. I know this sounds crazy however I have seen this numerous times when there are starting/accesory opertation problems.

You said it will start and then no start. Is that crank and start, crank and no start or no crank no start? This makes a big difference as to our ability to diagnose the problem. More information will be needed to help solve the problem.

As cheap as front engine wiring harness's are, I would replace the factory GM front end wiring harness with a new reproduction factory font end wiring harness if you have not done so.

This could also be heat related. I once had a Ford that was missing about 1 inch of wire insulation on a distributor power wire. The vehicle would start fine and run for about 20 minutes and quit. It would only start when the vehicle cooled off. I FINALLY found the small length of bare wire powering the distributor about 1 inch long with no insulation. I properly spliced the wire to remove the un-insulated section and the vehicle ran fine from then on! Apparently the heat build up (resistance) in the bare section of wire was so great that the resistance (Voltage = I current x R resistance) was so great that not enough current would flow through the wire to power the distributor. These wires were in a very hot area on top the intake and under the carb. So check all your wires. Better yet, get a new front engine harness!

[69CamaroRacer]

It will start run and I will shut it off then go to crank it and I get nothing... It does not matter how long it runs.. It is not heat related. I could drive the car for an hour and have the problem just the same as if it were sitting in the garage all night and I went out the next morning to do some tuning.. It will always start if I jump it. The battrie was just replaced and it did not change the problem. When I turn the key I get nothing... then out of no where it will start next time I turn the key but there is no real pattern. IT is an intermittent problem

[vintageracer]

Look at the wiring harness plug at the firewall. Remove the wiring harness plugs at the firewall fuse box on the engine side of the firewall and clean the connections. If the car is dead and a jump helps, corrosion could be the problem at these plugs. Also check the connection on the 12 gauge wire in the front wiring harness at the junction block on the passenger side of the radiator support and at the horn relay.

[Bandit]

I am by no means an electrical guru but I have had the same type of problem on different occasions and was able to narrow it down to a solution in my case.

One problem was the dreaded "heat soak" which others have mentioned as a possiblility. GM's in particular are notorious for this because of the location of the starter close to the exhaust. The starter gets hot while the engine is running, things expand, and it freezes up when you try to restart it. All you get is a clicking sound from the solenoid. Let it sit for an hour or so to cool down, things contract again, and vrroooom--you're back on the road. This could be part of your problem, but not the only one from the sound of things. The solution is to insulate your starter from heat using a protective heat wrap, or to buy a smaller aftermarket starter, or get a remote solenoid setup like Mad electrical offers.

The other problem I had was a bad connection to the solenoid on the starter and/or a bad solenoid itself. There is a lot of current travelling down the positive cable upon startup and if the connection is not really good then it will not always get enough to kick in the starter motor. On one such occasion, I wiggled the cable and the connection was tight, I thought WTF, finally I took it off and cleaned it all up really well and used proper star washers etc., and that fixed it. But another time my starter solenoid was bad and I had to replace it.

As far as why jumpstarting always helps start it, again, check your connections. Possibly just the act of wiggling cables around during jumping it re-establishes a good enough connection, and it starts.

Well I hope that gives you a couple ideas anyway...

[68nate]

I agree with vintageracer. Take a good look at the 12 guage wire for poor connection or corrosion at the firewall connector or at the ignition switch itself. When you have a problem like this and jumping the battery or hooking up a battery charger creates a change, It's almost always a corrosion or connection problem.