Engine won't turn with sparkplug in

[wild n crazy]

Hello all, Can some one please answer my question? greatly appreciated. My engine is a 100 HP outboard Evinrude, 1979 model. My issue is I haven't run the engine for 3 months, I have tried to start but it won't. So I took the starter out and clean and put it back together, I took the sparkplug out and clean and put back. The engine turn but not enough to start. but when I took all spark plugs out, and trying to start, the engine turn great, since there is no sparkplug, the engine turn freely, but as soon I put all the sparkplug back, the engine seem to stall and doesn't want to crank, battery is fully charge, So What is the issue for my engine? it turns great without the sparkplugs

 

[nwcove]

Corroded wires from battery, bad ground, weak starter. start by cleaning all connections from the battery to the motor.

 

[wild n crazy]

How can you tell it's a weak starter? I am not questioning your knowledge, I just ask to learn how to tell I have weak starter. And Thanks for your answer

 

[nwcove]

jump it from a known good battery to the starter.

 

[achris]

Can you turn the engine by hand with the spark plugs in?

A 'weak' starter could have a brush hung up. Take it to a local auto-electrician to test....

 

[Bosunsmate]

jump it from a known good battery to the starter.

Do as nwcove says, just make sure your jumper cables are good, some cheap ones dont make good connections

You can put the ground cable on to a starter bolt or some other clean ground on the engine

 

[wild n crazy]

Thank you Mr NWCove, I'll try that tomorrow and see, Yes Mr AChris, But when it turn, it's real hard resistance with the sparkplug in place. And also Thank you Mr Bosunsmate. I'll try tomm. and return with answer. Actually I've been taken the starter apart every time it does that, but the engine start, this time I think like Mr NWCove said, maybe weak starter

 

[F_R]

First clean all the cable connections. Don't just look at them, take them apart and clean them. If that doesn't work, what you need to do are some voltage drop tests. I suspect you need to come back for some education on what that is, right? Just ask.

 

[wild n crazy]

Thank you to all, including Mr F-R. I did undo all the wiring from battery to Starter , and buffed all the contacted area to where it shine. Then try to started again, first it did turn the engine, but then it quit, so I feel the starter, and it's hot. So I took the starter apart again, trying to separate all wires from near touch to barely touch, tightened screws and nuts . put the original shaft that I mixed and matched last time, ( I have two starters that I mix and match) Started again, and it crank like a champ. And yes, it is contact problem and power don't get all juice to where it needed to be. Once again I thank you all alot