runs good cold....but.....

[bsandy565656]

It was cool when we went out this a m. My 48 spl 1989 evinrude ran like a new one. I couldn't hardly believe it because we haven't got it running right since we got it last year. After it warmed up it started to act up like always. What do you suppose causes it to run poorly after it has run for a while?
Bsandy
We live in Fl.

 

[jonesg]

Re: runs good cold....but.....

acting up and running poorly aren't very descriptive, what precisely does it do?

To troubleshoot, use a timing light to see if it drops spark after warmed up, coils often fail when they get hot run can spark fine when cold.
Get a cheap timing light from auto store, I paid $27 for mine.
A $10 adjustable gap spark tester is very usefull too while you're there.

 

[bsandy565656]

Re: runs good cold....but.....

Like I said it was cool and for the first 8 to 10 minutes it ran perfect. I wasn't full speed but running fast, then it coughed some and slowed down to about half. It wouldn't idle long and would die if left alone. Starts up real good and will run half speed O K. When we got this motor it only ran on one cly. the bottom carb was plugged. Had it rebuilt and of course new plugs. It ran like a new one before it warmed up so i wouldn't think it is a carb trouble. Got any ideas? Commpression with plugs out are 139 and140 with a new gauge.
bsandy

 

[jonesg]

Re: runs good cold....but.....

Same as above, eliminate spark as source of trouble first then move on to fuel delivery. I'd expect it to be dropping spark.