Hi all, I'm new here, and to old Yamahas, I'm more familiar with old evinrudes. I apologize for a maybe long winded post.
I believe this to be a 1985-1986 Mariner 8M, but built by Yamaha. Parts fiches here list it as an 8B hp. I have a partial serial number (painted over) 677-0153
I got it in a trade, first thing I did was take the carb apart to make sure it's clean, and it looks like it was replaced after it's last outing (whenever that was) as there was no scent of fuel and none of the brass was discoloured. Everything was clear and I saw no problems. The fuel pump diaphragm looked good as well. I replaced the impeller and ran it in a tank for 30 minutes and all was well.
I took it out this past weekend, and it started right up, idled well at the launch, and we set about the lake. Ran it at 3/4 throttle for about 5 minutes and brought it back to an idle and all was well. Went back to a 3/4 throtle run for a few minutes, ran it at WOT for a few minutes, then back to 3/4 throttle for a minute or 2 and back to an idle. At this point it sputtered out and died.
Took the cowling off and fuel is dripping out of the carb. I managed to get it started and it would run, but not well and was spitting fuel out of the float bowl vent. Thought maybe the float was stuck, tapping the bowl with my multi tool made no difference. Got the boat back to the launch and back home and pulled the carb apart. I couldn't see anything jumping out at me, but I thought the float looked a little low so I adjusted the height.
Next day I went back out to the lake to try again. It started easy again and idled, revved up ok, took it back out and it was good for probably 30 minutes at various throttle positions, coming back to an idle etc. Had it out for a 3/4 throttle run for about 15 minutes straight, and it sputtered out again. This time I didn't have any fuel spitting out the carb. The filter was full of fuel. It did eventually start again, and ran clear at higher revs, but didn't want to run much below 1/2 throttle.
At this point I'm not sure what to check next. I'm not too familiar with these motors. Does anybody have any suggestions where to look next?
Cheers, David
I believe this to be a 1985-1986 Mariner 8M, but built by Yamaha. Parts fiches here list it as an 8B hp. I have a partial serial number (painted over) 677-0153
I got it in a trade, first thing I did was take the carb apart to make sure it's clean, and it looks like it was replaced after it's last outing (whenever that was) as there was no scent of fuel and none of the brass was discoloured. Everything was clear and I saw no problems. The fuel pump diaphragm looked good as well. I replaced the impeller and ran it in a tank for 30 minutes and all was well.
I took it out this past weekend, and it started right up, idled well at the launch, and we set about the lake. Ran it at 3/4 throttle for about 5 minutes and brought it back to an idle and all was well. Went back to a 3/4 throtle run for a few minutes, ran it at WOT for a few minutes, then back to 3/4 throttle for a minute or 2 and back to an idle. At this point it sputtered out and died.
Took the cowling off and fuel is dripping out of the carb. I managed to get it started and it would run, but not well and was spitting fuel out of the float bowl vent. Thought maybe the float was stuck, tapping the bowl with my multi tool made no difference. Got the boat back to the launch and back home and pulled the carb apart. I couldn't see anything jumping out at me, but I thought the float looked a little low so I adjusted the height.
Next day I went back out to the lake to try again. It started easy again and idled, revved up ok, took it back out and it was good for probably 30 minutes at various throttle positions, coming back to an idle etc. Had it out for a 3/4 throttle run for about 15 minutes straight, and it sputtered out again. This time I didn't have any fuel spitting out the carb. The filter was full of fuel. It did eventually start again, and ran clear at higher revs, but didn't want to run much below 1/2 throttle.
At this point I'm not sure what to check next. I'm not too familiar with these motors. Does anybody have any suggestions where to look next?
Cheers, David