Trimming prop kills motor

[tboothe]

I recently purchased a used 1996 Cobalt 190. We have used the boat five or six times. On the last two outings, while trimming the prop, the motor shut off. The first couple of times this happened, upon restarting the motor, it fired back up. However, after the third time, the engine would not turn over. I noticed after the first time this happened that the voltage meter was very erratic, rapidly moving from left to right. After the engine failed to crank, we patiently waited 5-10 minutes and then hopefully tried to crank it and luckily it fired back up and I immediately noticed the voltage meter behaving erratic again so we headed back to the dock. The boat ran fine just as ling as I do not attempt to adjust the trim. Oddly enough, after trailing the boat, with the engine off, trimming the prop to the full upright position for the journey home worked just fine.

Does anyone have a clue as to what the problem is? Is this a battery about to die? If this is a short, anyone have any advice as to specifically where to be looking? I am fairly mechanically inclined but electrical issues are not really my forte. Thanks!

 

[UncleWillie]

This sound more like a loose connection, an OPEN, Not a SHORT.

Find the loose connection. Start at the battery.
If it thumbscrews that you can move with your fingers, they are too loose.

 

[bruceb58]

Look at the connections at the battery as Willie has said and at the starter. I had a connection at my starter loosen up and it behaved in the exact way.

For the connections at the starter, take them off completely and sand then until they are shiny before replacing.

 

[tblshur]

dont forget the ground connection on the enjine good luck.:joyous:

 

[tboothe]

Thanks for the advice so far. For the record, the battery tested just fine so that is not the issue. @Bruce, are you saying that you experienced the motor cutting out when you trimmed your prop and this was attributable to your starter? This is confusing to me as I would figure the starter is only part of the equation in getting the motor running. Once the motor is running, why would a connection at the starter cause the motor to shut down?

 

[bruceb58]

No, the connections at the starter were/loose corroded. At the starter, the battery connects there as well as the feeds to the trim circuit as well as the rest of the engine/boat electrical system. When you trim and there is resistance , you get a huge voltage drop that will kill your ignition.

As the another poster remarked, you need to check the negative connection at your block. That can also cause your issue.

 

[Bondo]

Ayuh,..... Sounds like corroded wirin' ends/ connections, 'n/ or Bad grounds, probably for the same reasons,...

 

[litfuze]

could it be something like the shift cable pulling in and out while trimming shutting down the shift interupter switch??.....that may be worth taking a look at as well .....just my 2cents .

 

[UncleWillie]

It is unlikely the shift cable. It only flexes, not stretches while trimming.

The Trim motor is the second largest current demand item on the boat next to the actual starter.
It is common to hear the engine RPM slow slightly while trimming, just from the load it places on the alternator.

If there is any poor connection in the wiring, when the trim motor runs, the voltage drop is going to big enough to kill the ignition.
Watch the voltage gage, if it changes significantly while trimming, you have a bad connection somewhere.
The Positive AND Negative cables must BOTH be secure.