Runs good for a few minutes then jerks!

[sonnysb]

I have a 1957 18hp Evinrude. It starts really good & quickly. It runs fine for about a minute or two, then the motor will begin to jerk (reminds me of a car when the timing is off), then it will begin to want to stall. It has one of those old Johnson "Master Mile" 6 gal fuel tanks. I checked the line everything seems to be fine. I changed the spark plugs, sounds better, but still jerks around. Fuel filter looks clean and clear. I don't know what else to check. <br /> Has anyone run into this before, if so please advise me what you did to resolve it. I do have a low speed & high speed adjustment dials, but when I think the low speed is adjusted fine in nuetral, it begins to jerk once more.<br /><br />Thank you in advanced.<br /><br />Sonny

 

[ob1jeeper]

Re: Runs good for a few minutes then jerks!

Sounds like there's some small debris in the float bowl, which is sporadicaly floating up and plugging the idle fuel passages... I'd take the bowl off & make sure that it AND the idle passages are CLEAN.

 

[12Footer]

Re: Runs good for a few minutes then jerks!

Ob1 is right. But if you don't find it there, check the filter, connection on the tank, and pickup IN the tank. Also, look for water in the tank.<br />If you have >80 hours on your plugs,change them, they are done. Plugs don't last long on 2cycle engines.

 

[sonnysb]

Re: Runs good for a few minutes then jerks!

Thank you both for your quick replies! I will look this afternoon at the bowl and the passages. I have noticed a small air leak on top of the presurized gas tank, I don't know if that would have anything to do with it or not, but I will try to seal that too!<br /><br />Thanks again!<br /><br />Sonny