Totally dead after running for an hour

When something doesn't work it's a good plan to start at the battery to be sure you have at least 6 volts there, then move down the line to the starter switch. Check the voltage there, both with the starter switch at rest and while pushing it down to start. You should show 6 volts if the starter isn't working, and about 5 volts while cranking the engine. If you still show 6 volts at the starter terminal while the button is depressed, then the starter must need work, or the switch isn't making good contact with the starter lug.

The lights coming back on after 20 minutes is what made me think it might be a poor battery connection. Do you have a fuse, or a thermal circuit breaker in the system? These things are so easy to check in person, but can be tough over the internet, unless every detail is known.
 
I say you have a grounding issue, This is based on your statements,

"I replaced the starter switch and my 29 Sport Coupe fired right up." and "Totally dead. Will not crank. After about 20 minutes, the lights came on all by their self. Still dead when trying to crank."

The only thing in the circuit for the starter to work is the battery. One terminal to the frame the other to the starter switch, through the starter and back to the frame.

If the new switch was bad that would have nothing to do with the lights working. A bad ground could allow enought electricity to flow for the lights but not enough for the current requirements of the starter.

(your new battery could be faulty as well, but that would be a long shot in my opinion)
 
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As Dudley & others have said, BEFORE ANY electrical tests, ALWAYS make sure the battery is fully charged & in good condition! (Where's whatz'his name with the DEAD horse pic, we need it NOW!) Bill W.
 
As cheap as the replacement harnesses are why do people even mess around with trying to salvage one that is cut and spliced and cracked everywhere? Even the repro is going to be better than that. They even only take about an hour to install, it makes it a hell of a lot easier to chase problems.
 
29ModelA said:
As cheap as the replacement harnesses are why do people even mess around with trying to salvage one that is cut and spliced and cracked everywhere? Even the repro is going to be better than that. They even only take about an hour to install, it makes it a hell of a lot easier to chase problems.
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Ain't that the truth! I spent about two hours just trying to figure out what the previous owner had done with the wiring on my coupe, and finally said to heck with it, bought a very nice harness from Sacramento Vintage, and installed that in less than two hours.

BTW, I have used wiring from other vendors, and most are good, but I think SV takes extra care with theirs because they make them themselves.
 
I agree with the looms from Sacramento Vintage. I have installed 2 of them and compared to others they are superior.
 
Phil said:
Ok I guess there too many cooks in the kitchen. I will bow out. The man has a problem with his car. He wanted help in knowing where to look. Ever one was telling him to get a meter or light and test till he found it. Just trying to walk him through some steps. Sorry.
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Phil, kudos to you for trying to be helpful by specifically answering his question with a logical reply.
 
Phil: Noboby's "stepping" on your toes. He had a previous problem=fixed. This is a "new opportunity".
Ck his profile for previous posts. FWIW
Paul in CT
 
Phil said:
You asked where to start. Here is where. Take a volt meter and measure the voltage at the battery post. Not on the clamp, but on the 2 posts. Scrape the top of the post for a really good connection. You should have around 6.2 volts. If not charge the battery for an hour or so for further testing. If you have a little over 6 volt on the battery post next check voltage at the post on the starter and engine block (make sure you have clean metal where where your test leads touch) . You need the 6.2v here also. If not check and clean and make sure both cable at the battery posts and at the other end of each cable. When you have proper voltage at the starter post to engine it should crank. If battery was low and you charged it and now have 6+ volts should crank.
Make these checks and post here and we can go from here.
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I finally got my hands on a working volt meter. 6.2 at the battery and 6.2 at the starter. I disconnected the lights; no change. Going out to do more tests. I will report back later.
 
Tom Wesenberg said:
When something doesn't work it's a good plan to start at the battery to be sure you have at least 6 volts there, then move down the line to the starter switch. Check the voltage there, both with the starter switch at rest and while pushing it down to start. You should show 6 volts if the starter isn't working, and about 5 volts while cranking the engine. If you still show 6 volts at the starter terminal while the button is depressed, then the starter must need work, or the switch isn't making good contact with the starter lug.

The lights coming back on after 20 minutes is what made me think it might be a poor battery connection. Do you have a fuse, or a thermal circuit breaker in the system? These things are so easy to check in person, but can be tough over the internet, unless every detail is known.
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Tom,
I don't have a breaker or fuse in the system. Checked the ground connection and it is tight both ends. I removed it from the frame last week, ground the connection to bare metal, and tightened it back down. I'm going out to check voltage when starter is depressed.
 
go from the starter post where the battery cable connects to the starter body. with the volt meter do you have 6.2v

make sure you put the lead on the threaded post at the starter where the cable attaches .
 
With the volt meter still connected that same way starter term and housing
Push the starter button as to crank the motor

Does the voltage drop or hold steady at 6.2
 
Mitch//pa said:
With the volt meter still connected that same way starter term and housing
Push the starter button as to crank the motor

Does the voltage drop or hold steady at 6.2
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I don't have any help here right now. As soon as the wife gets home, I'll recruit her and perform that test. Report back shortly. Thanks for your help!

Dwight
 
if the voltage does not drop when depressing the starter switch then you have a internal starter problem or the new switch is not making contact inside as thomas stated in post # 21.

once this is corrected and you can start it up, hook up the voltmeter to the battery and elevate the idle to make sure the generator is charging the battery the voltage reading should be higher than 6.2 and the higher you race it the voltage should increase.
 
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Just performed the test with starter switch depressed. It dropped to 4.16. Turned off ignition switch for a minute and did the test again. Same result, 4.16. The new switch seems to be stiffer than the old one. It worked great for 5 or 6 starts before this problem.
 
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