'87 Phazer Problem - Snowmobile Forum: Your #1 Snowmobile Forum

JDS · 02-09-2005, 01:42 PM

This sled starts and runs fine until it gets warmed up. After it's warmed up, it'll be going fine when all of a sudden it bogs down and seems to be running on one cylinder. Then while you're trying to nurse it back, the other cylinder kicks in and it'll about throw you off the sled. This is my son's sled. Any ideas?

**smallengineguy** · 02-09-2005, 07:23 PM

Carb has a problem. Determine which carb it is by looking at the plugs. The wet one is the faulty carb side.

JDS · 02-10-2005, 09:52 AM

He took it to the dealer and they ran a diagnosis. They told him that it was the bushing between the cylinders was leaking. They determined this with a leak down test. A friend told me that if it wasn't leaking too bad, the sled could be run by wiring in a low pressure electric fuel pump. Does that make any sense?

He said that the reason it would start running on one cylinder was because the impulse to the fuel pump was being screwed up. If that's true, that would eliminate gas to both carbs?

Candlman · 02-10-2005, 12:27 PM

I have the exact same problem with my 90 Exiter 570. Runs great for 10 minutes or so and then boggs down at lower RPM's or climbing hills after warm up. Runs great at high RPM's. Shut it down for 20 minutes to cool and it runs great again for several minutes. I'm new to the sport so I have been reading all the threads I can for info. Seems likes many older Yamaha owners have similar problems. i plan to clean the carbs but I'm not sure why, if dirty, they would only fail after it warms up. Anyone have any suggestions?

600SE · 02-11-2005, 05:59 AM

Quote:

Originally posted by JDS
He took it to the dealer and they ran a diagnosis. They told him that it was the bushing between the cylinders was leaking. They determined this with a leak down test. A friend told me that if it wasn't leaking too bad, the sled could be run by wiring in a low pressure electric fuel pump. Does that make any sense?

He said that the reason it would start running on one cylinder was because the impulse to the fuel pump was being screwed up. If that's true, that would eliminate gas to both carbs?

Does make some sense, at least hes right about the bushing being there...on a 2 stroke the crank runs through it, keeps the cylinders separated at the bottom. Never heard anything about a fuel pump before.....I would pull the jugs off and replace the bushing if that is whats bad...

**smallengineguy** · 02-11-2005, 01:36 PM

Quote:

Originally posted by 600SE
I would pull the jugs off and replace the bushing if that is whats bad...

Wish it was that easy....You need to pull the crank, have it pressed apart and replace the seal.

JDS · 02-11-2005, 05:47 PM

smallengineguy: Yeah, I know how to fix it, but that may have to be a summertime fix. Looks like we're not going to have any snow for awhile anyway.