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Discussion Starter · #1 ·
Well, I couldn't resist getting an early start on winter so I decided to fire up the sleds to make sure there would be no suprises this season. I summerized them by adding oil to the cylinders so I knew I would have to blow out that oil first. The 570 fired instantly but the 370 was having problems. I thought it was just too much oil still in the cylinders but after half hour of cranking (without spark plugs) I was pretty sure I had gotten it all out. I checked for spark, it was fine, then I manually injected some fuel into the carburator. It was the (lack of) fuel that was causing the problem. As soon as I filled the carb bowl it fired right up. So my question is... does anyone know what the method of fuel delivery this engine uses? I can see the line from the tank, goes through the manual shut-off valve, through a fuel filter, then it goes into this "thing" that I assume is some type of fuel pump, and from there right to the carb. The pump (if that is what it is) is flat mounted and has another inlet (besides fuel in/out) that may be vacuum.

Just some history too. This sled always had a minor issue with stalling at idle. When it happened I could just fire it back up and all was well. I initiall thought it was a carb setting, But now I am thinking it may have a fuel delivery problem at idle. My manual does not get into this area at all.If anyone can shed any light on this system it would be appreciated.

Steve
 

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I am Spartacus
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Steve,

The flat thing is indeed the fuel pump. There is an inlet, outlet and a pulse hose that uses crankcase vacuum/pressure to move the pump diaphragm. The pumps are easily rebuildable (the hardest part is actually getting the pump out of the sled :D ). Idon't think it would cause the idle stalling though. The pump would have a harder time keeping up at high speed than idle. Wen it stalls, do you have to open the throttle, or just pull it over?
 

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Yeah, that shouldnt be causing an idle stall. is it an efi(if 370 even comes in efi, i dont ever pay attention to anything lower than the 440) If so you might have a screw loose in your throttlebody. I had that happen last year and m sled would idle at about 750 instead of the normal 1500.
 

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Discussion Starter · #4 ·
Maybe I'm not explaining it correctly. The sled usually ran fine, always fine under throttle, but every now and then it would stall when stopped for a minite or so at idle. But this latest problem was definetly lack of fuel in the line. I could see it had no gas in the line. After I primed the carb a few times it seemed OK but stalled again when I let idle. And once again I could see it was out of fuel. It seems the pump is OK when on the throttle or under load. BTW, it's just a single carb model, no EFI. And it was purchased brand new last year. Maybe I should measure vacuum at idle. Thanks for IDing the pump, I think I'm still under warranty for a few months so I'll see what the dealer thinks.

Steve
 

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should see the problem with the fuel pump while rpms are high not when they are low. doesnt make sense. take it to the dealer definetely if you are still under waranty. and let us know what the problem/solution was so we all know in the future if it ever comes up again. good luck steve.
 

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Check for a cracked/loose pulse line (the line that provides vacuum to the pump). Under hard throttle, the engine vacuum would compensate for the leak, but would cause the problem at idle like you said.
 

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steved28 said:
Maybe I'm not explaining it correctly. The sled usually ran fine, always fine under throttle, but every now and then it would stall when stopped for a minite or so at idle. ...

Steve
Sounds like a simple idle adjustment. Does it idle real low when you stop... sometimes it will keep up, and somtimes it will stall??? Sounds to me like you have to "up" the idle a little bit. What RPM are you idling at (when stopped)?
 

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Discussion Starter · #8 ·
Well, smallengineguy hit the nail on the head. (probably why they call him smallengineguy!). I put the vacuum line under pressure and there was a hairline split. I cut the offending part off and all is well again. I have to assume this was some kind of factory defect since the sled only has one season on it. Idles like a charm now.

Thanks!

Steve
 

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glad to hear it. now if we only had some snow everything would be great!
 

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Thanks small engine dude! Now I have to go check the line on my 440. It sometimes stumbles then stalls at idle. Other times, it idles fine. I upped the idle adjustment, but if the problem is the vacuum, I better fix the cause... rather than react to the symptom. ;)
 
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