evinrude 3 hp

[Dave Hostetter]

After careful carb cleaning, my nice evinrude lighttwin from late 60’s or early 70’s starts easily and idles smoothly. But on a small light boat, it won’t speed up like it does in my test tank, except as it’s running out of gas after I’ve closed the fuel shutoff valve. What can I do to make it run more strongly?

Dave H

[wedgie]

Have you adjusted the carb ?What model is it ?

[lindy46]

If it’s a 3hp, it’s 1968 or older. Does it have an adjustable high speed needle or just the adjustable slow speed? If it has an adjustable high speed, that needs to be adjusted on the lake at WOT. Start out with the needle open about 3/4 turn, and then adjust for maximum speed/rpms.

[david-bartlett]

Also, make sure it is running on both cylinders. These motors will idle quite well on only one cylinder, but will not have any power when throttle is advanced.

[fleetwin]

Engines tend to rev up more in the test tank due to turbulent water/ventilation, so you may not really have a problem at all. But surely take the time to adjust the high speed needle while running on the boat, unless it has a fixed high speed jet.

[Dave Hostetter]

It’s got both low and high speed adjustment knobs. Adjusting the high speed knob doesn’t have any effect. Coils tested ok this summer. Will put spark plug lights on it to check whether both cylinders are firing under load.

Dave H

[frankr]

If adjusting the high speed needle has no effect, the gasket may be missing on the main nozzle. But more likely is it is just open way too far. It will run rich till you get it somewhere close to optimal setting, then it will make a difference as you fine tune it. It closed down too far, it will cut the gas off and it won’t run. You obviously haven’t gotten it that far leaned out yet.

[Mumbles]

If it acts like it is running out of gas, maybe it is running out of gas!

The small fuel line, shutoff tap and the filter screen in the tank all tend to get dirty and plug up over the years. If you undo the fuel line at the carb and turn the gas on, it should flow quite freely. Don’t forget to open the air vent on the tanks filler cap! If it doesn’t flow freely, a thorough cleaning of the fuel system is required.

[Tubs]

quote FrankR:

If adjusting the high speed needle has no effect, the gasket may be missing on the main nozzle. But more likely is it is just open way too far. It will run rich till you get it somewhere close to optimal setting, then it will make a difference as you fine tune it. It closed down too far, it will cut the gas off and it won’t run. You obviously haven’t gotten it that far leaned out yet.

A "Boathouse Repair" is one that done without having tools or the skills to do it properly.

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