90 yamaha not on all cylinders

[jmackay]

Recently inherited an outstanding flats skiff with a 90 Yamaha that had not been run in 2 years. Engine starts, but does not appear to be running on all cylinders. I suspect a tune up should dolve the issue, but what is the most likely source of the problem? Carbs? The gas I know is old and there wasa no stabilizers added to the fuel when the boat was no longer in use.

 

[99yam40]

Re: 90 yamaha not on all cylinders

You need to drain and clean the whole fuel system. Tank, lines, primer bulb, pumps and carbs.
maybe hook up new portable tank with new lines and bulb, just to make sure you can make it run properly if it has a built in tank.

But first I would make sure all cylinders have good compression and there is good spark on all plug wires before doing anything else