Hot Rods Electrical Help what to check next!?

My roadster just cut out / died the other day. It fired right up, I got about a 1/2 mile from my house and it just died.

Trying to pop start it I managed to run myself over with it.

A neighbor came by and gave me a jump- fired right up ( and ran like mofo)!

the moment I took the cables off it died again



I put about an hour and 1/2 into the roadster last night... No dice

What do you bros think??

battery: 13.0

solenoid: 13.0

Key switch: 13.0

Light switch: 13.0

regulator: 13.0

When I turn the light switch on, the power goes to 0 at the light switch

When I turn the key switch on, the outputs go to like 2.8, as well as the input- battery still measures 13

Bad key switch? Loose wild ground? I’ve double triple checked the terminals on the battery- best connections ever!

What should I check next!? Heeelllppppp meeeeeeee.....

Thanks,
Jake

 

Bad ground

 

Go back through the main feeds starting at the battery posts and clean and tighten each connection. My thought is that you have enough contact at a connection to carry the voltage to read on the test meter with no load but the minute you get a load on it the resistance in the connection is too high to carry the load.
Pull and clean the battery cables and check the posts of the battery to make sure they aren't loose in the battery. Check the cables where they connect to the cable ends. Then work you way down the line on both sides.
Quite often I have seen the bolt or nut that holds the ground cable to the block be loose or in one case too long and bottom out before it got tight enough on the cable end. Also paint behind the cable end on fresh engines is a big issue, you need bare shiny iron behind that cable end.

 

Me think also.

 

Grab one jumper lead and go straight from the battery negative to the block (on a clean bolt maybe). Do the same with the other lead, but going from the battery negative to the frame (again on a clean bolt head).
Try to kick it over. If it runs, remove one jumper lead at a time. If one of them kills the motor (or lights),you have a bad ground to either your motor or frame, whichever you removed.
good luck.

 

Do you have 3 solid grounds? I like to ground the battery to as close to the starter as possible as this is the greatest draw. That could mean at the bellhousing, the engine block, or even the transmission case. Second is a equally good ground from the engine to chassis, or battery to chassis. Third you have have again a equally good ground for the body/cab/interior. Again based on your setup, this could be from the engine or the frame to the body. remember, grounds will not go through paint, so having a clean area to attatch the ground is very important. Also, I like to use STAR washers to lock down the fastener for the ground connection. The STAR washers not only lock the nut, but also they bite into the lug of the ground cable. Have the battery load tested. TR

 

Battery could have bad cell which only shows up under load .

 

I'd swap in a "known to be good" battery first and see what happens. Of course go over all of your grounds as well. Your good voltages could be reading the battery condition. If you can get it running, disconnect the negative battery terminal, if it stalls, it probably is not charging.

Bob

 

A shorted cell in the battery could do this very easily.

bob

 

make sure to check your tire preassures. ok seriously though you are checking available voltage with your volt meter that is why the problem hasn't surfaced, what you can also do is a voltage drop test under load, put the + on one end of the cable and the - on the other end, and hit the key / headlights / any other large draw item, when you find the cable with issues the meter will read how many volts you are loosing. do you have fusible links in the car?

 

This is an invaluable tool for this circumstance



Load the battery down and see what happens and use it to see if the alternator is charging

You can also connect it to the positve on the battery and to your grounds to show resistance

 

I don't like using that test, because for one it can burn out regulators, but also when you do that the voltage regulator thinks the system is totally discharged and kicks the alternator into full amperage output, which is a hell of a load on the engine which can also cause the engine to stall. best to test the alternator with an inductive amp clamp on the charge wire, if you don't have one of these any autozone / csko will, that is if you can get the car down there, but you can also take the alternator off and have em bench test them too. I never like to see people test the charging system by taking the battery out of the system, because it also acts as a voltage stabilizer.