Intermittent "bogging"

[bill4157]

I have a 1980 70 Hp evinrude. It ran good last year, only problem was that it was a little cold blooded...so after fall I winterized it. This summer I got it out of storage and had it gone through at the marina. Rebuilt carbs, new fluids, new water pump, new plugs etc. It ran great for the first two weeks. But for the past month it only runs good once in a while. Some times it will run fine, other times it will run good for about 10 minutes and then start intermittently bogging at 3/4 to full throttle. Then other times it will just not right well at all and only have about half power and bogg down.

I tried new plugs (it has good spark), new fuel pump and I have always ran premium gas and made sure my oil mix is spot on.

Any suggestions?

Thanks

 

[xjdriver]

Re: Intermittent "bogging"

Check for air leaks in the fuel system, also see if pumping the primer while bogging helps, check pickup in tank. mine had the same prob, it was a weak fuel pump even after rebuilding it, but you say you have new. Sounds like a fuel prob to me.

 

[boobie]

Re: Intermittent "bogging"

When it bogs down do a cylinder drop test on it and see which cylinders aren't firing and see if there is spark or not.

 

[bill4157]

Re: Intermittent "bogging"

How do I do a cylinder drop test??

 

[boobie]

Re: Intermittent "bogging"

When the problem occurs pull one spark plug wire at a time with an insulated pliers and see if the motor will drop in rpm. If it does you know that cyl is firing.