Boat Gremlins :(

[Tequila Dawn]

Hey folks need your help again :cry:

Took the Grady out on the lake for a sunset cruise. Perfect night for it, glass smooth, warm. Then it happened. Just after the no wake bouy I got her on plane and noticed the tach acting irradict then it went to zero. Just as that happened the motor started sputtering and loosing power. I backed off and the motor recovered. Got back on plane and the motor ran fine for a few minutes but still no tach. After we anchored up I raised the motor to look for a fouled prop, nothing. Water pickup clear. Took the cowl off and the tach wire was intact and tight. Figured it was just a hicup.

After doing a little night fishing we decided to head home. Motor cranked right over but no power. Without the tach still I cant give you an RPM figure only estimating it at 2000 rpm was all we could achive. Got her back to the dock and on the trailer thankfully.

What in the world could be going on now?

Thanks in Advance for any help.

 

[Grog]

How's the gas? Have the carbs ever been cleaned?

 

[JUST-IN-TIME]

helps to know what year and hp please

 

[Tequila Dawn]

Gas is fine, as far as I can tell. Its a 10 gallon fuel cell that was filled 2 weeks ago. New Water Seperator and plugs.

The boat is a 1976 Duke 175 with a 1978 Mariner 80hp. The carbs haven't been cleaned by myself but previous owner had a tune up before selling, supposedly.

 

[gerrys]

The tach acting up simultaneously with the motor would suggest an electrical problem, not fuel. Many tachs get their signal from a sensor on a plug wire. Assuming this is the case on your motor, I'd check the plug wires with particular attention to the wire with the tach sensor. A loose plug wire will cause rough running and loss of rpm's.
Let us know what you find.

 

[catch22]

Don't know about Mercs, but on older OMC's, when you would lose your tach, that usually meant your regulator was going. Don't see how a regulator would effect plug firing, but it definitely sounds like an electrical problem. Power pack, (if your 78 has one) would be my first guess... magneto, (magnets under flywheel) pick ups, triggers, etc. It could even be your ignition switch. They usually ground out the power pack when switched to "off", but the contacts can get corroded and hold the ground connection when switched to "run".

 

[Tequila Dawn]

Thanks for the advice guys. I will go and look when I get home today. I will keep you all posted.

 

[JUST-IN-TIME]

pull the tach wire off the tach
then go try it