1976 merc cut out at mid range

[Fishin4Life]

Hey guys. I am looking at getting a boat from a family friend. I took it out and ran it a few times today and noticed that at mid range throttle it cuts out and if you don't slam on the gas or back off it will die. If you idle up then slam onto WOT it doesn't have any issues at all, and runs out good at WOT. Any ideas on what this could be? The boat has been sitting for three years, put in new gas and some sea foam. But the owner had it tuned up each year and they said it has always done this... so I don't think it is from being gummed up.

Any ideas would be helpful. Maybe a cost idea on how much it will be to fix to work that into the price of the boat...

Thanks!

[eurolarva]

Sounds like a bad stator. I believe you will need a DVA to test it.

[boatfixer]

What HP is this? When you sat it cuts out, does it sputter or does it just instantly die out? One thing I would take a look at are the stator and trigger wires coming from from under the flywheel. look for bare spots. Alot of the older mercs have deteriorating wires and insulation. If you know the approximate position of the throttle handle when it cuts out, move it to that position and see if you can find where it might be touching the block or other places for grounding, (with the engine turned off of course).

[Fishin4Life]

Sorry I forgot to put that in. It is a 70 hp. Are the stators generally expensive to repair? What is a DVA? Sorry I am not up on the repair stuff for boat motors yet.

It seems to to sputter a bit and then die out, like it is struggling to run. At the dead spot it will surge, then die out, then surge then die out, until it eventually quits running. Any other ideas? I know it won't hurt, but do you a think a good rebuild of the carbs could solve it? Or does it sound more electrical?

I will check out that throttle link tomorrow to see if it touches anywhere. Thanks for your help

[boatfixer]

rebuilding the carbs is a good idea. If the motor has sat for a while, installing a new impeller is also strongly suggested.A new stator will run you about 150.00-175.00 for parts. A DVA is an electrical test meter used to measure peak voltage on high voltage ignitions, such as the one you have. Stators like the one on your motor, have low speed and high speed voltage. typically, when stators fail, it won't start at all, or it wont run past 1000 rpms. There is a chance that the windings are grounding when you advance the throttle. Either way, I would have a look at the basics first. Electrical parts are quite expensive to replace and dealers will not take them back. If you can't find something with the fuel system, (filter, carbs, hose & bulb, connecters) I would suggest taking it to a shop to have the ignition system tested.

[Fishin4Life]

OK great, thanks for all the suggestions! I will check those all out.