MGB MGB Dead Short?

[Tonopah Kid]

1971 MGB appears to have a "dead-short", just happened "overnight", Installed a new WOSP hi-torque starter several months ago, car isn't drive-able, but it's in the garage and I start it every couple of weeks and warm it up before shutting down. After the last start, about two weeks ago, when I tried to start it did about 5 seconds of cranking and then abruptly stopped. the interior light, fuel pump, etc went dark. I tried to start but no response, no lights, etc. When under the hood, check for 12v, there was 12v at the starter, but when I jumped the starter solenoid there was 12v, but no reaction from the starter, which still showed the 12v.

After a period of time 10 minutes? the interior light came back on, fuel pump started running, went to turn key to start, "clunk" everything went dark, but there was still 12v and the starter. I then connected jumper cables to the starter terminal and grounded to engine, 12v showed at the starter, fuel pump running, turn key to start and clink, and black-out.

What's going on here?

 

[DrEntropy]

Not trying to be funny, but p'raps rodents?

 

[JPSmit]

Sounds like battery to me - can you try a known good battery?

 

[PAUL161]

Do you have a battery maintainer hooked up? How long do you let the car run before shutting down? Could be the battery isn't getting enough charge to compensate for the starting drain and the battery is going flat. PJ

 

[DrEntropy]

And BTW, if there were a "Dead Short" someplace in the circuitry you would know it by the smoke coming directly from the harness.

 

[bobhustead]

To Doc's point, a short is a direct connection between the battery poles with no resistance in between. Sounds like a bad battery or maybe a ground connection failure. The latter could be at any ground connection, engine to frame, body to frame, engine to body, etc. Try a jumper cable from the engine block to the earth pole of the FULLY CHARGED battery.
Bob

 

[Roger]

Sounds like a bad ground to me, check the battery ground.

 

[LarryK]

Just because battery is up to voltage doesn't mean it is up to the load. Try a load test. When things come back on and die again, battery load.

 

[Joe Reed]

You can take the battery (fully charged) to almost any auto parts store and they can load test the battery for you. If the battery doesn't have a full charge they'll have to charge it before testing.