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Help with 4 H.P. 1971 Evinrude

C

chopper72

New member
Started running at about half power and lower RPMs. I cleaned carb and it started right up and runs the same. What next steps would you take? Thanks!!
 
Do a compression test and a spark gap test and get back with the results. Put a phillips screwdriver in the plug wire and hold it approximately 1/4 inch from a good ground and have someone pull the rope. It must jump a 1/4 inch open air gap with a brite blue snap.
 
What a classic symptom of a motor running on one cylinder. Probably ignition (spark) problem, but could be a bad spark plug or loss of compression on one cylinder.
 
Thank you guys. I am away from home and don't have all my tools so it is taking some time to respond. I pulled the spark plugs and the top plug had a nice residue of fuel on it and was dark throughout. The bottom was dry at the tip and base. Not sure what that means. Both cylinders have blue spark. I don't have a compression tester but their is a fair amount of oil residue around the head gasket. Do you think that could be the problem? I will try to get to an auto store tomorrow to do a compression check. Thanks for your help!
 
Does the spark jump a gap of 1/4" or more , yes or no ?----------That is the way to define " good spark ", most folks do not seem to understand how important that test is.
 
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