Frustrating start problem

**UPDATE** - It seems as though the starter is the issue. I took it to cars and coffee this morning and it ran fine going there. Went to leave, and dead. I put it in gear and moved it only a bit (didn't even get out of the car, just rocked it) and it started right up! I'm not going to give up on the grounding possibility - this car sat for at least 5 years prior to my purchase, so it can't hurt. But it looks like I'll need to pull the starter and play with it.

Thanks again to everyone for advice! I'll keep you up to date on progress!
 
First thing to is while trying to crank the engine smack the strarter with a hammer. Hopefully it's not a nice, restored starter. Mi used to working on fleet vehicles where you could beat on them. Sometimes but not always it will start cranking if the brushed are starting to fail. You can do this when they are first failing but eventually the smack test won't work. That was the first thing we did when we know we had battery voltage and an engine would not crank. If it cranks when you smack the starter you can be pretty sure the starter is at fault.

If that don't work than this is what you need to do nest, a "voltage drop test" across every switch, cable and connection while you are trying to crank the engine. It will definitely find the bad spot. This is how professional mechanics find those opens and excessive resistance in circuits. It's an easy test to do. I would start with testing across the starter switch, the contacts are could be burned.

Resistance is a blockage just like a blocked water pipe. If you were to drill holes in both sides of the blockage in a water pipe you could route the water flow around the blockage. That is exactly what the voltmeter is doing in a voltage drop test. The voltage can't get by the blockage, so it tries to flow through the easier path of resistance through the meter and you see it as voltage reading. There should not be more than .1V to.2V volt drop or there is resistance. Current has to be flowing to do this test.

Watch this video and there are many others on voltage drop testing. You must have a voltmeter to work on electrical stuff or you are just guessing. Your starting circuit is much simpler, but the testing is the same. Doesn't matter if its 6V, 12V negative or positive ground this how you diagnose it.

https://www.youtube.com/watch?v=WMX...AIqfImoqnA&start_radio=1&rv=WMXENKujYtc&t=633
 
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**UPDATE #2** - Well, it finally cooled off enough for me to play with the roadster. I got new battery cables including the copper positive version like the original. I removed both of the old ones, took a wire brush (drill-end kind) to the connection on the frame and transmission, reassembled the system, and it starts like a charm! In fact, it seems stronger too. Now, that said, I started it about 8 times this morning with no problems - but this was intermitant, so the next test is to start it several times over the next few days and see what I come up with. I'm cautiously optimistic, though. Thanks again for all the tips!!
 
rivcokid, x2 on post 22 except for his following description:

"That is exactly what the voltmeter is doing in a voltage drop test. The voltage can't get by the blockage, so it tries to flow through the easier path of resistance through the meter and you see it as voltage reading."

You can find a description of how to "voltage test" the Model A starting system in Chapter 2 of the blue, Les Andrews "Trouble Shooting and Diagnostics" guide. There are other simple volt meter tests for faulty connections etc.

Warning: an ohmmeter cannot be used to find a faulty battery cable or wire.
 
@ Rob Doe - Sorry. I'm just getting back to this now. Until recently, the car was doing just fine. The grounding strap was apparently the problem. Just recently, though, it decided to start doing it again. I remember that I bought and installed one of those original looking straps. It barely fit - and I mean barely! It took me quite a few tries to get it ont here because it was too short. I'll work on "reshining" the connection point first, and if that works, fine. If not, I'll get a new cable (proper size) and not make sure it's long enough!!
 
Good Evening...I was working on a Model A that had not had much love in a while today. Much the same problem as discussed above. Come to find out the the aftermarket ignition switch was past the end of its useful life. Changed the switch and all was well...Ernie in Arizona
 
Rivco,
I have experienced the same frustration with bad grounds. But there's a way to virtually eliminating the ground gremlins. Buy some aggressive external tooth lock washers large enough to handle to bolt going through the ground cable in the chassis or body and install them on BOTH sides of the cable going to a clean ground attaching point. The teeth of this type of lock washer bite into the metal of the body, cable, and bolt in several places. In fact, most of the OEM's used this method for years to anchor the ground cable or other ground contact points to the car.

https://www.mcmaster.com/products/standard-washers/lock-washers-2~/mil-spec-tooth-lock-washers~~/

https://ceautoelectricsupply.com/wp...8/Internal_External_Star_Washer_Install_3.jpg
 
1. Are you using one of those cheap battery disconnect switches connected to your battery cable? If you are , remove it and only use the cable connection.
2. Have you tested the ignition switch?
If the answer is "No" then try bypassing your ignition switch. Temporarily remove the 2 wires going to the switch and connect them together with an aligator clip jumper wire. If you can start the engine repeatedly using this temporary connection, replace your ignition switch.
 
Hi CT Jack - I don't have a battery disconnect on it. However, I have not tested the switch. Thanks - will try to do that this weekend.

@McGarrett - Thanks for the idea and link. I was thinking perhaps of just replacing the battery cables as they are old anyway. Get some new 2/0 lines going at the same time as cleaning up the ground area. Thanks!!
 
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