Electrical Aggravation

OK,the day before yesterday I went to start my '73 S&S (stock except for aftermarket oil press/water temp/ammeter gauges and switchable electric fuel pump by the tank) Turned the ignition to the accessory setting,turned on the electric fuel pump for about ten seconds,turned it off,turned the ignition to star,got a soft "clunk" as all the lights went out at once and wouldn't operate again.No sound at all when I tried the start position on the ignition,no headlights or interior lights,either.

Later that evening I opened the door and the interior lights came on nice and bright.Tried to start it again today.Everything was fine until I turned the key to start,then I got the same scenario as before.

Diagnosing any electrical problem,especially at a distance,is a little dicey,but does anyone have any suggestions as to which closets to start looking in for the electronic skeleton(s)? Thanks,guys.
 
Check the ground

I'm no electrical wizard but what I've learned from this board is no matter what the electrical issue, always start by checking for a good ground. Clean the battery terminals and connectors well. Also check the ground strap/cable where it attaches to the motor or chassis.

From there...well, I'll let the electrical pros speak to that.
 
The lights coming on and then a clunk along with darkness would leave me to believe that it is a bad positive connection at the battery. I suggest that you remove both battery terminal ends, and using a batter terminal wire brush, clean both the terminals and the battery posts. If it continues to give you problems, then loosen and then snug up the ground wire where it attach's to the engine block. If your car has the ground wire going to the frame, then I would relocate it to a bolt on the engine. If it still gives you problems after you do this, then it is high resistance in the positive wire that goes from the battery to the starter solenoid. Once again, some will chase their tail and do the checks in a random method, and stop once they get the car started, only to find that they didn't find the complete problem.
 
same as my problem

I made it to the gas pumps went to restart after refilling and clunk It was on mine the after market battery clamps that the wire slides in and two bolts tighten down on the wire the clamp had power but the wire did not so I have replaced them with new wire with the machine ends like it came from the factory $45.00 at napa fix the problem on my 68
 
As one who spent 20+ years in the Towing business I learned quickly that #1 Starters usually give an indication they're going before the actually do and #2 the quick roadside diagnosis was usually: If you've got lights and they go out when the key is turned it's a battery. Sometimes a Jump will work but a stone dead battery sometimes can be charged and won't take it anyhow.
 
yes charge the battery. if the voltage is to low to start the chunk is the solenoid going in they the lights are out. go back in and check later the voltage comes up a bit and the lights work. usually a bad connection as described is not letting the battery charge back up or it just gone bad.
 
Sucess.....Maybe

Paul's mention of the positive terminal got me thinking,so I got the Mrs. (who got an "A" in high school auto shop-I didn't even take it) to watch the interior lights with the door open while I wiggled the positive battery cable.Sure enough the lights flickered.I took the terminal apart,sanded off the gunk and corrosion,put it back together,hooked it up and everything seems to be working fine.Started right up several times.
About a month ago,the top radiator hose let go and got coolant all over.I think maybe the positive terminal was so gunked up that the connection went bad.I'll bear in mind that the battery is not the only thing in the engine compartment that got wet,so Miss Thing won't be going out for a spin just yet.
Thanks again for all the ideas and direction .This isn't the first time y'all have made a big difference.:thankyou2:
 
It's worth noting that if the cable CAN be wiggled, you have a problem. And sometimes even when the connection seems tight, you still have a problem. One trick we used to use way back when... tap a flat bladed screwdriver between the battery post and the cable clamp.
 
It's worth noting that if the cable CAN be wiggled, you have a problem. And sometimes even when the connection seems tight, you still have a problem. One trick we used to use way back when... tap a flat bladed screwdriver between the battery post and the cable clamp.

The last thing that I would want to be doing is using a screwdriver in a way that it was never intended. There is only one way to safely check a battery terminal end, and that is to take it apart. If you use a screwdriver you run the risk of damaging the battery post, or causing a spark that can cause the battery to explode. Yes, the chances are remote, but if you happen to be that one in a 100 people that has a battery explode in your face, then the other 99 don't matter. This advise to use a screwdriver to test a connection is tantamount to putting a penny in the fuse box when the fuse blowes.
 
:poster_oops:I misspoke....it was the end of the positive battery cable that I took apart and cleaned,not the battery terminal post.In my car,both battery cable ends are like big washers and attach by screws to the recessed terminals on the side of the battery.Sorry!
 
that would look to me like a electric pump that has been added and discarded. the tipical stuff you find on most of these cars. they would add stuff rather then repair the car. it was to be a cure for hard starting and vaper lock. most have ended up like this one.
these old gals sit you need to coach them back to life by pumping the H out of the carb. you got to use starter flued get the carb rebuilt. all the gas is draining out of it as it sits.
 
I won't repeat what was written above, as everyone seems right on the money, in one way or another. I'd just like to say that the interior lights draw far less amperage than the starter motor. So seeing interior lighting is not at alllll a guarantee of being able to turn the starter motor.

Following up on what Paul wrote, though, I've made it a habit...... 100% of the time...... to remove the NEGATIVE clamp from the battery FIRST, and make it the LAST connection after doing electrical work on the car. This way, if a screwdriver or pliers happen to ground a positive lead to the body or frame (all negative), you won't risk an arc. Tom
 
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