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1982 Evinrude 50 issue

Mac300

Member
Ran my boat for the first time this year. Cranked it at the house on a hose before I left to make sure all was in order and it ran fine. Got to the river and the gas station I buy non ethanol gas from was closed. I had a tank with old gas- at least one year old, possibly 2, so I took a chance and used it. Boat ran fine for a few minutes then started surging and losing power. Restarted and ran fine for a mile or 2 and did the same and quit running. It did this several times and finally got to the point that it would not start at all. Towed it back and went home. Removed both carbs and they were very clean and the jets were clean also. I had rebuilt both carbs last year and had only run it a few times so I expected them to be clean. I was assuming it was just water in the gas but the more I think about it may be something else. I remember that while running fast it started making a sucking sound and several seconds later it would stall out and die. It did this 2 or 3 times. Then it just got harder to start and it would die as soon as I applied gas. Now I'm wondering about an air leak, I've never had that isssue before. Would that make it not start at all? Also wondered about the fuel pump. I planned on cleaning the fuel tank and lines, and seeing if the fuel pump pushed gas thru the lines when I turn over motor. Then reinstall the carbs and see what happens. Not sure how to find a possible air leak. For what's it worth, the sucking sound came from the motor, not the line from the tank to the motor. Also, the bulb was firm and not collapsed or soft.

Any thoughts would be appreciated. Thanks
 
Have you ever tested the overheat horn ?----Has water pump impeller been replaced recently ?----Results of a compression test will help here.
 
Will your spark jump a 7/16" open air gap on a spark tester ??

I have not tested that but I can. I was thinking I might have fouled the plugs trying to get it restarted so was going to put new ones in. I will test them first. The symptoms seemed to be like I was running out of fuel and then sputtering until it quit.
 
I have not tested the horn (didn't realize it had one). I put a new impeller in last fall as general maintenance. It pees out water strong.
 
. I did a compression test last fall before storing for the winter and had about 120 on both cylinders.

Yeah, and now it did run. BUT---it quit. The question is what broke. Test the compression. You are letting your imagination get away from you with all those imagined possibilities. Time to do some orderly troubleshooting.
 
Racerone and fdrgator. I hope to get to the camp this weekend and do a compression test and spark test. I don't have reliable cell service there so if I do have adequate compression and spark I plan on checking all fuel lines thoroughly for blockage/leaks and will also use a different tank and supply line if needed. Is there a way to test the fuel pump other than just cranking the motor a seeing if fuel is being delivered at the carbs? Any advice on other steps to take? I know I'm jumping ahead but it is 70 miles away and I want to have a plan in case the compression and spark are good. Thanks
 
I just watched dangar marine fix a similar issue. He went through everything prior though. Did the steps kinda backwards. Start with the easy things and work your way out. I’m not sure you can even test the fuel pump the way you say as it’s driven by the compression from the cylinder. If you disconnect it from the carbs then you lose the compression for the pump to work. You don’t need to turn over the engine. Just hook up your main lines and disconnect the hose that feeds the carbs. Mine is connected with a T way. Disconnect the T way and pump the primer bulb. If a good steady stream comes out the pump you are good fuel pump wise.
Check your linkages. I believe that is what’s messing up your motor. Be sure your timing stops are in the correct places. Idle screws are not all out of wack. Butterflies are closed and synched up. Check your coils too your sparks to be sure they are getting current. Easy things.
 
Found the culprit. Had a small crack in the fuel line between the inlet on the cover and the fuel pump. $1 worth of new line and it runs great. Thanks for the replies.
 
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