truck has a 318 engine 2barrel carb. Truck was running fine it sit for a few days and now it will barely turn over even with two maximum heavy duty Semi batteries hooked up. I pulled all the plugs out and it spins freely, so i then check my timing marks there good, help please!

 

Sounds like the starter could be weak. Have you tried cleaning your grounds? Also check to make sure there are no cracks or swelling in your battery cables.

 

I have had three different starters on and the grounds are good check with a DMM. What would cause the motor to spin freely with plugs removed and barely move with them in?

 

compression is what would slow it down with the plugs in. without the plugs in there is nothing stopping the air from rushing out of the cylinders. how does the oil look? how does the transmission fluid look?

 

oil and tranny fluid are in great shape

 

Does the distributor rotor button turn when you turn the engine over? The timing chain may have let go.

 

yes it turns

 

The starter may be OK for a light load (plugs removed) but not have the guts to turn the engine once you add the compression load. Things that can cause this are.

1. Starter connections that are not tight or are corroded.
2. A burnt starter solenoid contact ring.
3. Worn starter commutator rings or worn brushes.
4. Broken brush springs.
5. Partially grounded windings.

I would pull the starter and have it tested to determine the electrical draw load.

 

ok i will have the starter tested and get back to you. So there is nothing else that could cause this problem?

 

Since it turns freely and the cam is turning there is nothing internally wrong to cause this. It is going to be a bad ground or power connection, or a starter problem. I don't recommend using a DMM to test grounds. You can get enough of a ground to test OK with a DMM and still not be a good enough ground for the amperage to turn a starter.

For trouble shooting you might try running a jumper cable from the battery negative down to something on the starter itself (like a mounting bolt or flange) to eliminate the possibility of a ground problem. You can also run the jumper positive straight to the battery lug on the starter itself to eliminate the trucks wiring as a problem. If either of those work you know what circuit the problem is in. If they don't work the starter is all that is left.