engine and drivetrain Slow to turn over-strong battery, newer starter, alt...help!

[OH2DRV]

Okay, so here's the deal-

What would cause an engine to turn over once and stop even when the key is still in the "start" position? It refuses to turn further, behaves like a near-dead battery.

However, I'm ruling out the battery and starter because-

*The battery is fairly new, measures 12.45 VDC

*Starter turns great with coil wire disconnected

It must be ignition wiring or timing then right?

If it is timing, would excessively retarded timing or advanced timing cause it to turn over once then stop? Which one? Or either?

Any ideas as to how I should troubleshoot this one?

Thanks!

[Chris_B]

Excessively retarded timing will cause slow cranking, because the ignition is firing too soon, which pushes against the effort of the starter to turn the motor over. However, a weak starter motor or battery will cause the same symptom, even if the timing is set fairly close to correct.

Retarded timing will not prevent a motor with a healthy starter and battery to simply not turn over... it will only slow cranking.

Your reading of +12.45 at the battery = only ~75% charged, so that could well be your problem. There is a big difference between how a 100% charged battery ( +12.6V for a standard lead acid battery) and a 75% charged battery will turn over a motor. Even at 75% charge, your battery should be able to turn over the motor. Could be a combo of retarded timing and/or low battery and/or poorly operating starter.

I suggest that you get your battery charged, and then try rotating your distributor slightly a few degrees fore and aft while cranking the motor. That will help you determine whether any of the these problems is causing your symptom.

[Chris_B]

meant to say timing too advanced, of course, rather than retarded. Too many beers, apparently.

[OH2DRV]

Chris,

Thanks for the tips...yeah I figured you meant advanced...which makes more sense- there is combustion far too long before the cylinder gets to TDC...

I'll try retarding the timing a little and charging the battery too, although it turns over real fast and strong.

Thanks,

Andrew

[Squarepusher]

dont get on me if im totally wrong or off topic cause i didnt even read the question, all i read was the subject. my answer is you might not be grounded properly.

[Guest Anonymous]

dont get on me if im totally wrong or off topic cause i didnt even read the question, all i read was the subject. my answer is you might not be grounded properly.

WTF were you thinking???? could be right actually but probably too advanced on the timing

[KFunk]

I was actually thinking the same thing: grounding problem. Take off the big ground strap on the engine, sand it down and clean it with contact cleaner, and put it back on. Maybe even replace the whole ground cable, you can get a cheap 4 guage battery cable at a parts store.

As for timing being too advanced: i've done this a few times before, and the starter turns just as fast, but as soon as the engine fires, there's a sudden kickback against the starter, and you know things aren't right. It's a distinct kick backward and stopping of everything. Never heard it just crank slowly.

[KFunk]

come to think of it, i actually had a very similar problem before.

I may have been a little off track, as I was misunderstanding the 'slow to turn-over' and thought you meant slow spinning of the starter. But you meant 'turn-over' as the engine fires and turns itself over.

So anyways, on my car, I somehow fried the resistive positive wire going to my coil. But there's a wire going from the starter over to the coil as well, and its meant to bypass the resistor and give the coil full power while the starter is engaged, and give you a nice cold start.

But in your case, maybe you still have this bypass wire in place, and your coil only gets power while the starter is spinning. The normal resistive wire could be melted or broken or grounding out somewhere. So when you let off the key, the coil doesn't get power anymore.

If you're using a blue coil, you don't need a resistive wire or ballast resistor, so just use a regular heavy guage wire over to your relay. You can also get rid of the bypass wire if you have a blue coil.

[Squarepusher]

4 gauge, no man get the thickest wire you can. wait im probably thinking of the wrong thing, is 4 gauge think?

[OH2DRV]

(nt)

[OH2DRV]

http://www.powerstream.com/Wire_Size.htm

Wire gauge/size/amp ratings....

[Squarepusher]

original poster, is your horn really weak sounding? because mine was untill i got a new ground strap to the block, then it was super loud. limp horn=bad ground

[OH2DRV]

(nt)

[jtmasters68]

That's one of the most helpful and exhaustive sites on wiring that I've ever found. Thanks so much for posting the link!

[bnam]

Check the grounds -- battery negative to ground and engine block to ground.