1988 70 hp Yamaha Losing RPM's

[Panthermatt]

Idles fine runs good for about 1/2 hour at all speeds. When going over a wake after a 1/2 hour it loses RPM's gradually. Then it is acting like it is running on one cyl.. It seems like a second cly. tries to kick in. After it idles for 20-30 min. It will run normal for a little while then do same thing.<br /><br />Maintenance performed already.<br />1) Carbs cleaned<br />2)New Water pump and lubed lower unit.<br />3)All grounds checked and are secure.

 

[Panthermatt]

Re: 1988 70 hp Yamaha Losing RPM's

Anybody???

 

[Ray Neudecker]

Re: 1988 70 hp Yamaha Losing RPM's

Take a timing light with you and see if fire is correct while acting up. Do a compresion check before you go. Take a bottle of white out and mark the flywheel for each cylinder to check for timing and fire.

 

[fmenezes]

Re: 1988 70 hp Yamaha Losing RPM's

I had a similar problem with my 70 HP yamaha once. It would run fine, except in rough water. I found that I had water in my external fuel filter/separator. Once I replaced the filter it ran fine. You, too, may have water in your fuel tank.