Troubleshooting Snowmobile

Alright I am hoping a mechanic may be able to help. Apologize in advance for the long read. I would take the sled in to get repaired but everywhere I’ve called is 4+ weeks out.

Sled is a 2010 Arctic Cat Bearcat 570 2 stroke. Last weekend while using for ice fishing, sled would randomly bog down and about half power. If I feathered the gas, it would come out of it back to normal after a bit. Parked it that night, started the next morning but died during warm up and then wouldn’t start again. Carbs were completely rebuilt last year by a dealer and sled was looked over as it sat for 11 years before I bought it with 60 miles on it. When I unhooked the fuel line from the fuel pump to one of the carbs and pulled the sled over, no gas would come out. Checked the line from the pick up line in the fuel tank all the way to the fuel pump, clear and good. Just replaced the fuel pump with a new one and cleaned out the bowl/floats on the carbs while they were out. Everything looked good. Checked for suction on the pulse line and could feel it pulling on my finger. Primed the system with fuel and started first pull. Idled for a couple mins just fine. Shut it off and tried to restart after a min. Nothing. Not sure where to turn now, hoping someone might have an idea

Any chance theres a crack in one of the carb boots?

Youbetcha wrote:

Any chance theres a crack in one of the carb boots?

As in the rubber boot from the air intake? That is in good condition

The rubber boots the carbs fit into on the engine side if that makes sense.

Youbetcha wrote:

The rubber boots the carbs fit into on the engine side if that makes sense.

My fault. As you can tell I’m not super knowledgeable on small engines. But don’t really have a choice if I want to keep using the sled for this ice season.

Yes those are in good condition as well

It sounds like a fuel delivery issue. Being it sat so long at some point clean and replace everything from the tank to the carbs. It had 11 years for that corn gas to go bad.

Send a PM to Iowaboy1, Sheldon will be able to get you headed in the right direction.

Good luck, let us know how it turns out.

Might be a dumb question, but have you checked for spark when it wont start?

Dutchboy wrote:

It sounds like a fuel delivery issue. Being it sat so long at some point clean and replace everything from the tank to the carbs. It had 11 years for that corn gas to go bad.

Send a PM to Iowaboy1, Sheldon will be able to get you headed in the right direction.

Good luck, let us know how it turns out.

I do agree it is a fuel issue. Like I mentioned above, I had a dealer go through everything last year. Ran great and put a couple hundred miles on it. This year it wants to be a PITA

I am currently watching the sled idle. I primed the system with fuel again and got it started. Been idling for 12 mins now just fine. The issue seems to be pulling in fuel at startup

Joe Jarl wrote:

Might be a dumb question, but have you checked for spark when it wont start?

I have not but I am able to get it started when fuel is in the system. Plugs are also new

Have you emptied the tank completely and cleaned it ever? Sounds like fuel problem from the tank itself.

My first thought is that a crankshaft seal is dried out and sucking air.
When that happens there isnt enough pulse strength to operate the fuel pump and the carbs will run out.
With the engine running spray some WD-40, brake cleaner or the like right at the seal area where the crankshaft comes out of it behind the clutch, if the seal is leaking the idle will change.

If you find it is leaking do not continue to run it or you will burn a piston in short order!!

If you dont see a change in the idle quality then you are fighting an air leak in the suction side of the fuel system, it doesnt take much more than a pinhole to create problems.

Sad to say low miles means nothing on the seal life, they are notorious for leaking after a bit of time and eleven years is a long time to be sitting, that will kill them faster than being used everyday.

Iowaboy1 wrote:

My first thought is that a crankshaft seal is dried out and sucking air.
When that happens there isnt enough pulse strength to operate the fuel pump and the carbs will run out.
With the engine running spray some WD-40, brake cleaner or the like right at the seal area where the crankshaft comes out of it behind the clutch, if the seal is leaking the idle will change.

If you find it is leaking do not continue to run it or you will burn a piston in short order!!

If you dont see a change in the idle quality then you are fighting an air leak in the suction side of the fuel system, it doesnt take much more than a pinhole to create problems.

Sad to say low miles means nothing on the seal life, they are notorious for leaking after a bit of time and eleven years is a long time to be sitting, that will kill them faster than being used everyday.

Are you referring to the seal/gasket with the red or yellow arrows on this pic?

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I think he means the seal on the driveshaft itself behind drive clutch.
The shaft the spins the belt to transfer power to the shaft the spins the track. Would be on the side of engine. Not the front.

I think thats what I’m understanding at least.

Where the yellow arrow is. If nothing happens I would replace every fuel line. I’d also make sure the choke cable is free and not hanging up.

Was the line in the tank replaced? Common for those to dry out and crack in the tank and cause these issues.

Thanks again to IowaBoy1 for troubleshooting with me over the phone. Sled is currently running but I will be cleaning out the gas tank and replacing the fuel pick up line per his recommendations