80 hp Mercury 1980 vintage

starts runs but when put in gear it dies–any ideas –thank you

Clean out the carbs

If you live in the TC area, give Supreme Marine in Minneapolis a call. They specialize in Mercs, even the ‘vintage’ ones.

If you are comfortable doing it yourself, like Jesse said, get carb kits and clean them. You can find lots of online resources about how to do this.

X2 on the carbs be esspecilly attentive to the low speed idle/pilot fuel circuit. Those passages are the smallest and most notorious for clogging. Gas formulations are now more prone to producind scale rather than gumming so Carb cleaners won’t dissolve scale. You need to mechanically remove it. I pluck a wire from a wire brush and hold it with a vice grips and probe all the orifices and jets. Good luck.

In addition to the carb cleaning, I can think of a few other things to try:

1. Plugs. New plugs and look up the correct gap. Yes, the actual setting of plug gaps still varies, you cannot just use .030 as a “standard” setting. The gap of the plugs is especially critical at idle.

2. Make sure the carb and throttle linkage are correctly timed. Commonly called a “link and sync” procedure.

3. Do you have a fuel filter on this engine? Check and replace if you don’t know when it was last changed.

4. Air leak in the fuel hose or fuel lines. This can be very difficult to track down. The easiest test is to put a different fuel hose on and see if that solves the problem. For under the cowling fule lines, you just have to replace them all.

BTW, all of this is assuming you’re running fresh, high quality fuel and that it’s NOT contaminated with water. Water contamination is always possible, even with fuel that just came out of the pump. Use a nice clear glass jar and generally I like to use a hand syphon/pump and pump up at least a pint of fuel off the BOTTOM of the tank to inspect it.

Grouse