I have a 1975 35 HP Evinrude that would start fairly easy run for a short time then start sputtering and acts like a backfire and dies. I went through the carb and cleaned it again and then went through fuel pump for the first time and one of the two springs that was embedded in the plastic casing was sideways so I reset that and carefully put it back together with the OMC diagram so those two parts are good to go.
I got it going again and ran very well for several minutes (much longer and better than before carb and fuel pump cleaning) then sputters/backfires and dies. Starts back up only for a very short time and dies. It did that a couple times and now won't start at all.
Good even compression around 120-125 top and bottom. Pumps tons of water and stays cool. Tested spark after having issues and seemed spark was intermittent but could have been bad connection on tester but pretty sure it is strong (at least a 1/4" gap, didn't measure exactly could have been more). Top plug was darker and both were wet and they were new plugs. Cleaned them up and still won't start. Primer bulb was staying fairly firm and even tried pumping when starting to die and didn't matter.
I believe it is an electrical issue and possibly bad or dirty points so I pulled the flywheel. The points looked nearly new but were a little tight with the tolerances so I reset them and cleaned with a business card and sure enough they were dirty. There was a small amount of what appeared to be fuel around the points and other areas nearby.
My question is, is the sputtering/backfiring/kickback caused by dirty points or does it sound like I have a coil heating up and going out when it warms up or...? I should probably replace the top seal regardless since it appears it is letting fuel passed it. Any other ideas? This thing ran like a top for at least 3-5 minutes then started having issues.
Thank you.
I got it going again and ran very well for several minutes (much longer and better than before carb and fuel pump cleaning) then sputters/backfires and dies. Starts back up only for a very short time and dies. It did that a couple times and now won't start at all.
Good even compression around 120-125 top and bottom. Pumps tons of water and stays cool. Tested spark after having issues and seemed spark was intermittent but could have been bad connection on tester but pretty sure it is strong (at least a 1/4" gap, didn't measure exactly could have been more). Top plug was darker and both were wet and they were new plugs. Cleaned them up and still won't start. Primer bulb was staying fairly firm and even tried pumping when starting to die and didn't matter.
I believe it is an electrical issue and possibly bad or dirty points so I pulled the flywheel. The points looked nearly new but were a little tight with the tolerances so I reset them and cleaned with a business card and sure enough they were dirty. There was a small amount of what appeared to be fuel around the points and other areas nearby.
My question is, is the sputtering/backfiring/kickback caused by dirty points or does it sound like I have a coil heating up and going out when it warms up or...? I should probably replace the top seal regardless since it appears it is letting fuel passed it. Any other ideas? This thing ran like a top for at least 3-5 minutes then started having issues.
Thank you.