Hi, I have looked through old threads but cannot find an answer.
I have a 1983 50hp 2 stroke Evinrude on my Picton Delta. The engine is an "E50BELCTA"
When I bought the boat it had stood for 3 years since being serviced and not used. I put fresh fuel in it flushed it through and took it out to try, it hesitated as it accelerated and then cut out after 1 minute.
Knowing that it had stale fuel in it previously I stripped the carbs and cleaned them in an ultrasound carb cleaner for a few hours and then re-assembled with new gaskets, new float, new needle and run a jet file through every jet to insure the size is as marked on them. I then replaced the fuel pump diaphragm, spring, filter gauze and gaskets. I replaced the fuel lines, primer bulb and fuel coupling. Next I checked the reed valves, replaced the spark plugs and ran it up on the flush muffs.
The engine runs beautifully on the flush muffs, to check the fueling I ran it at 3500rpm for 20 mins on the muffs - perfect running, returned to idle smoothly and would rev high and return to idle every time I tried it.
Thinking I had cured the problem I took it back out on the water, it started perfectly and after warming on high idle I put it into gear and cruised out of the marina, as soon as I open the throttle it picks up, hesitates and then cuts out and will stall or if I return the lever it comes back to idle.
The fault is there as soon as the revs increase under load, it does it if I creep the lever up or go straight for WOT. I have checked the primer bulb is firm and checked the fuel bowls and plugs - there is definitely getting fuel through.
The engine will run again at idle after a bit of cranking but will not pick up at all. As soon as I got home and run it up on the muffs it worked perfectly at all RPM.
I am guessing that there is an ignition fault and it is loosing spark or getting a weak spark under load that is being blown by the increased fueling. The engine does not pop, bang, misfire or splutter, it does not run on 1 cylinder so I cannot think that it would be carbs or individual coils. The engine starts quickly and smoothly when cold or warm so I am also assuming that the compression is good.
Has anyone had any experience of this or any ideas for ignition diagnostics? I do not own a DVA to test with at the moment.
I have a 1983 50hp 2 stroke Evinrude on my Picton Delta. The engine is an "E50BELCTA"
When I bought the boat it had stood for 3 years since being serviced and not used. I put fresh fuel in it flushed it through and took it out to try, it hesitated as it accelerated and then cut out after 1 minute.
Knowing that it had stale fuel in it previously I stripped the carbs and cleaned them in an ultrasound carb cleaner for a few hours and then re-assembled with new gaskets, new float, new needle and run a jet file through every jet to insure the size is as marked on them. I then replaced the fuel pump diaphragm, spring, filter gauze and gaskets. I replaced the fuel lines, primer bulb and fuel coupling. Next I checked the reed valves, replaced the spark plugs and ran it up on the flush muffs.
The engine runs beautifully on the flush muffs, to check the fueling I ran it at 3500rpm for 20 mins on the muffs - perfect running, returned to idle smoothly and would rev high and return to idle every time I tried it.
Thinking I had cured the problem I took it back out on the water, it started perfectly and after warming on high idle I put it into gear and cruised out of the marina, as soon as I open the throttle it picks up, hesitates and then cuts out and will stall or if I return the lever it comes back to idle.
The fault is there as soon as the revs increase under load, it does it if I creep the lever up or go straight for WOT. I have checked the primer bulb is firm and checked the fuel bowls and plugs - there is definitely getting fuel through.
The engine will run again at idle after a bit of cranking but will not pick up at all. As soon as I got home and run it up on the muffs it worked perfectly at all RPM.
I am guessing that there is an ignition fault and it is loosing spark or getting a weak spark under load that is being blown by the increased fueling. The engine does not pop, bang, misfire or splutter, it does not run on 1 cylinder so I cannot think that it would be carbs or individual coils. The engine starts quickly and smoothly when cold or warm so I am also assuming that the compression is good.
Has anyone had any experience of this or any ideas for ignition diagnostics? I do not own a DVA to test with at the moment.
