For those of you that might have read my other thread about some electrical problems I am having, see if you can figure out what might be going on here. I took yesterday off away from this project to see if I could come up with some tests and here's what I did tonight. I left off in the other thread that when I turned the ignition to ON it was completely dead.

I did leave out that this is(was) a *new* battery(850 cranking amps), but was sitting in my garage on boards for the last 7 months.

So.... here we go.

1) I again turned the ignition switch to the ON position tonight and nothing. I then put a charger on the battery for about 30 minutes and while the charger was still attached I turned the ignition ON. Full power everywhere with the shift light coming on bright and then going off as it is supposed to.

2) I disconnected the battery charger and attempted to turn the motor over about a turn. No problems at all.

3) I decided what the hell-o and pumped gas to the carb to see if I could again start it up. It tried to start it, but not quite. I pumped a bit more gas to it and it again just about wanted to start. I adjusted the timing a very small amount and hit it again. This time I heard the starter gears hit the flexplate with a ding sound(solid sounding face to face quick contact - not teeth engaging) and a complete loss of power. Any attempts to turn the ignition on resulted in no power at all.

4) I let it sit for about 30-45 minutes and again put the charger on it. Ten minutes later I went out and turned the ignition to the ON position(charger still attached, but not attempting to start) and the shift lite was just fluttering a weak on and off light. And I could hear a small popping sound at the battery when the ignition was ON. I put my hands on the wires to the starter to see if they were overheating and nothing.

Any clues from this? Possibly something in the starter is shorting when that misengage happens? I remember just about every time that when the power went dead it was that same hit of the flexplate.

 

Two thoughts:
1. Check both ends of you negative battery cable to make sure you are getting a good ground.
2. Make sure the engine ground cable is in good shape. It should be attached between one fo the passenger side motor mount bolts and the frame.

 

I had problems with cables once. The corrosion was in side the crimped cable end. Cut and clamped a new one on whala! This can happen at an one of the ends. You could probably check with and ohm meter and wiggle but it might not show you anything as a meter has milliamps verses the cars need for hundreds of amps. You could take the battery out, unplug your coil wire and use jumper cables to see if the starter acts better. If it does, you know it's in the wires.
Just some ideas off the top of my head.

 

Kevin_73 & Freepop,

I have checked the cable from the block to the frame a few times, but have not gotten under the vette to take a look at the ground by the battery. I've had the battery(& and an older one) out of this thing a few times, so it's possible the connection could have loosened or the wire itself gotten damaged. Thanks for the suggestions.

 

bgrice, the corrosion problems I was talking about would not be evident by looking at. The reason I said to take the battery out is so you could reach the starter solenoid with the jumper cables.

 

I would have a look at the seat belt interlock circuit. It is unique to the '74, and although the symptoms are a little different it could be a contributing problem. On my '74 I had an intermittent no-start condition. I narrowed it down to the interlock because I was able to crank the car over with a screwdriver to the solenoid with the key on whenever it didn't want to crank normally. I zip-tied the interlock relay and haven't had any trouble since. Your's may be more intermittent, or if the circuit has been removed or altered that may be part of the problem as well.
Good luck!
Jeff

 

Jeff,

Where is this interlock circuit? Under the seat? I would assume that most '74 Coupes probably came with both the lap and shoulder type safety belts since even my '71 has them. But, if you will remember this vette was converted to a vert back in '89 and only has lap belts now. Are you saying that possibly I could just engage the seat belt clips on each side and possibly see if that takes the problem out?