115 slow cranking

I just bought a boat with a 115 johnson and when I treid to get it running it was cranking very slow on a fresh battery. I bought a new starter only to find the same exact problem. It almost seems like the motor hads to much compression. When I take the plugs out it cranks fine. If I put one spark plug in it cranks slow again. Can anyone tell me what they think might be going on. Thanks

Re: 115 slow cranking

year? model? but my guess will be dirty connections, or bad battery cables.

90% of starter problems are bad connections. remove and clean both ends of the battery cables, so that they are shiney, also the cable from the solenoid to starter. check for nicks in the cables. and make sure the connectors are on the wire good. the cable tend to corrode from the inside out, if nicked, corroded wires, and connections, heat up and cause resistance to the follow of electricity, thus the starter doesn't get enough. you can also take jumper cable pos battery post to large post on starter. with a good connection, the engine should spin. then if the starter is good clean everything and retest. then trouble shoot solenoid. starters can be rebuit at a starter/alternator shop, much cheaper than a new one.

also have the battery load tested at the auto parts store, free, i've had new batteries go bad

Re: 115 slow cranking

Changing parts is the most used, most expensive and least effective troubleshooting method known to man, Bonanza.

It will cost you nothing to take those cables off, clean them and then reinstall them.

Re: 115 slow cranking

Another way you can test the battery yourself is if you have a voltmeter, check the voltage on the battery while you're cranking the motor. A bad battery will still show 12 volts with no load on it a lot of the time, but if you see it dropping a few volts when cranking the motor after the battery has been charged, the battery is toast.

Re: 115 slow cranking

JB said:

Changing parts is the most used, most expensive and least effective troubleshooting method known to man, Bonanza.

It will cost you nothing to take those cables off, clean them and then reinstall them.

Click to expand...

Very well put. Clean the cables and connections first.

Re: 115 slow cranking

This is a duplicate post. The first was posted on May 9th at 9:30 pm. Same recommendations.