HELP!!! Truck isn't starting

[81scottsdale]

1981 chevy k10 305 with 4 barrel edelbrock and headers - Okay guys I didn't know who to turn to anymore so I'm hoping someone here will have experienced something similar. Ever since I've bought my truck its had an issue starting when the engine is at operating temperature. Latelybits gotten worse and worse and now sometimes bit has done bit when the engine is completely cold. Also the starter and alternator were replaced a few months ago and same with the battery. Still same problem it would be okay for few days then get worse and worse l, now not only would it taken some time to get it started it also cranks over very very slow like the battery is dead. Finally for other reasons as well I changed out the engine for another used 305. For the first 5 days everything was normal it started right up every time even when hot. But last night I drove it home not even a mile, and this morning I turned the key and the engine would not turn over at all. I checked everything top to bottom again and all was normal, so I decided to hardwire the starter with my own switch to bypass the ingition switch and words completely and hooked up jumper cables to another truck even though I was getting almost 13 volts from hot to the frame. This time the engine turned over a 1/4 turn at a time and stopped. Same thing basically, so I decided to take off the stsrter . I took it to a shop and had them bench test it and....starter is perfectly fine. PLEASE someone help me out here any suggestions the junk yard is starting to sound good

 

[350runner]

Sounds like the battery to starter cable needs to be changed

Sent from the dust in front of you!

 

[81scottsdale]

I just replaced both battery cables yesterday and for whatever reason same thing

 

[MadOgre]

How about your grounds. Ground wires are the other half of the circuit and just as important as positive cables.

The starter grounds through the engine block, so you need to make sure the block is grounded to the battery and cab very well

 

[81scottsdale]

My next guess is to try to actually ground the starter directly to the battery negative just to see if the sob will actually turn the engine over?

 

[MadOgre]

My next guess is to try to actually ground the starter directly to the battery negative just to see if the sob will actually turn the engine over?

you could hook a ground cable to one of the starter mounting bolts

 

[81scottsdale]

I'll let you guys know what It does

 

[chengny]

Where do you have the engine end of the negative battery cable connected? It is generally bolted to the alternator bracket. You might want to try bolting it directly to the block somewhere.

If the starter bench tests okay and there is adequate power available and the hot cable is known good - you sound good on the hot side. So - that basically only leaves the ground leg.

On the ground leg:

The starter windings are grounded through the starter casing, which is bolted tightly to the block, the block is essentially just a big conductor. Your grounding cable (from the battery negative to the connection on the block/engine) is known good - in theory that only leaves the connection at the engine end of the negative cable.