No power when hot - Help please

[cantwetalineenough]

Please help, My year old 75 hp Mariner OB 2 stroke (Mercury) is losing power when it warms up. <br /><br />The motor has 40 hours on it and recently had the carbs and fuel lines cleaned. After warming up it runs great for 5 minutes then the power drops, like its running on only two cylinders only. If I let it sit for twenty minutes it does this all over again. <br /><br />I understand motors well enough but I am very new to outboards. This seems electrical. Could it be one of the three coils? And what is a 'power pack' is that similar to a cars module. Could I diagnose this problem at home or should it be done on the water to put the motor under load. Or buy a coil and use trail and error. Or take it to the shop that's so busy right know I'd loose my boat for two weeks.<br /><br />How about running the motor in the complete dark, this worked for a bad coil on a old motor bike of mine. (Sparks are given off be shorted coil - or so I'd heard)<br /><br />Kev

 

[Greg22]

Re: No power when hot - Help please

CWLE,<br />You can ohm out the coils and compare readings. Looking for an short or open. That is a good start. The power pack is similar to a moduele in an auto. Delivers spark to the ign. coils. If you want to find out if the pack is bad, get a can of freeze spray and cool the pack down after it has heated up. See if the engine runs good for a little bit. If yes, power pack. Easy to change. Hang in there and you will solve the problem. Don't ever just throw $$ at the problem. If you still need help check back. ry the search function for more info. I have learned a lot of good things from the folks here. Thanks iboats.

 

[Greg22]

Re: No power when hot - Help please

 

[cantwetalineenough]

Re: No power when hot - Help please

Cool idea, I don't have freeze spray here in Canada, but if you turn a can of compressed air upside down, viola same thing. And I can't wait to check those coils.<br /><br />Thanks Greg<br /><br />Kev