Cuts off at idle (video of offending motor included)

Blue_Runner · #1 03-21-2019, 01:13 PM

Finally got off my @ss and cleaned/rebuilt the carbs on my 2 stroke yamaha 150. Did not replace floats. By cleaning, I mean carb cleaner and compressed air. Anyhow, she's still misbehaving. Before and after carb work the motor runs strong entire spectrum. Problem is it cuts off frequently at idle. Any help is appreciated on what to look for.

https://photos.google.com/share/AF1Q...RTTmMyanVWQmN3

THEFERMANATOR · #2 03-21-2019, 01:42 PM

Carb cleaner and compressed air isnt going to remove heavy varnish. You need something to soak them in that will completely clean them.

Blue_Runner · #3 03-21-2019, 01:48 PM

Thanks Ferm. Carbs didn't look very dirty to my untrained eye. Could fuel pump cause this symptom? I had a bad fuel pump when the motor was only a few years old, but that impacted my ability to get up to max rpm, not idle. I've seen at least one instance online (must be true!!) where a motor was doing similar to mine at idle and it was confirmed to be fuel pump(s)

SkunkBoat · #4 03-21-2019, 04:59 PM

nothing about that video rules out ignition.

seems to stop not sputter out.

Blue_Runner · #5 03-22-2019, 07:18 AM

Sometimes it will cough and manage to keep running. The particular time in the vid it had done it maybe 20 seconds earlier, then once I got it on video it was ready to quit.

phatdaddy · #6 03-22-2019, 08:36 PM

on my carbed merc, when the fuek pump was getting weak, i would notice it when trolling. the motor would start dying. i could run back and pump the ball a few times and it would pick up and be ok for a while. next time it starts to stumble, try pumping ball.

like skunk said, video sounds like u cut the switch off

THEFERMANATOR · #7 03-23-2019, 10:11 AM

When the pump fails they normally stop pumping, leak fuel into the crankcase from a ruptured diaphram, or leak externally. If it was a weak pump, you'd have to go back and pump the primer bulb to restart it.

Blue_Runner · #8 03-25-2019, 08:25 AM

I agree, not the best video. Just before I started filming it really showed it's @ss. I do have to sometimes squeeze the ball to get it going again. I think I'm gonna replace the fuel pumps ($100) and see what happens. I've paid more than that for a diagnostic fee before

Appreciate the replies, will keep you guys posted on the outcome.

SkunkBoat · #9 03-25-2019, 08:45 AM

you probably already know this but....make sure the arrow on the ball is pointed UP at the motor.

THEFERMANATOR · #10 03-25-2019, 02:27 PM

Have you tried pumping the primer bulb while its running? This would basically be using you/the primer as the fuel pump. I just rewatched the video and it sure sounds like a lean sneeze to me that shuts it off.