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WOT start when warm

George Majewski

New Member
Messages
9
Age
54
Location
LaCrosse, WI.
Country
USA
Years Snowmobiling
35
Snowmobile
99 xc 600
I have a 99 xcsp 600 with primer and choke. After riding, I have to WOT for it to fire up. Already gone through carbs. Fuel pump rebuild?
 

George Majewski

New Member
Messages
9
Age
54
Location
LaCrosse, WI.
Country
USA
Years Snowmobiling
35
Snowmobile
99 xc 600
Choke looks all good. Never pulled out the reeds. Runs excellent when riding. Gonna rebuild fuel pump and go from there. Thanx for the response.
 

Mike-DRH

Member
Messages
82
Age
56
Location
Hastings
Country
USA
Years Snowmobiling
40
Snowmobile
2019 Polaris Rush 800
To much fuel would be the root cause for needing WOT on start. Pull the impulse line from pump to crankcase. The impulse line should be completely dry inside the line, if not, the diaphragm (in the pump) has a hole in it. That's the only way for fuel to enter the engine directly from the pump. Most likely cause would be the sealing o-ring on the needle & seat assembly in the carb. The only way to know for sure if the sealing o-ring is bad is to pressure test thru the fuel inlet nipple with a low pressure pump and bubble fluid.
 

850Switchback

Active Member
Messages
154
Age
45
Location
CT
Country
USA
Years Snowmobiling
30
Snowmobile
2020 Switchback XCR
The Keihin PWKs on that sled didn't have an o-ring on the float, that was the Mikuni design on the later engines. The Keihin float needle is rubber tipped and seated to the carb body itself. Since they are likely original and the rubber was from the pre-ethanol era its a good chance they might be shot.
Here's a exploded view with aftermarket part#'s, see #8 in the diagram. Polaris wants $45 for a replacement fuel needle.
 

Mike-DRH

Member
Messages
82
Age
56
Location
Hastings
Country
USA
Years Snowmobiling
40
Snowmobile
2019 Polaris Rush 800
1639533071819.png


This is the pump we use in our shop, bubble fluid can be a simple soap and water mix in a spray bottle.
 

Mike-DRH

Member
Messages
82
Age
56
Location
Hastings
Country
USA
Years Snowmobiling
40
Snowmobile
2019 Polaris Rush 800
The Keihin PWKs on that sled didn't have an o-ring on the float, that was the Mikuni design on the later engines. The Keihin float needle is rubber tipped and seated to the carb body itself. Since they are likely original and the rubber was from the pre-ethanol era its a good chance they might be shot.
Here's a exploded view with aftermarket part#'s, see #8 in the diagram. Polaris wants $45 for a replacement fuel needle.
Your right on, I was thinking later models. You can still test the needle & seat the same way. Or maybe a leaking primer? Pinch the line or try a Mighty Vac.
 

George Majewski

New Member
Messages
9
Age
54
Location
LaCrosse, WI.
Country
USA
Years Snowmobiling
35
Snowmobile
99 xc 600
Fuel pump looks good. In process of rebuilding. Any tips on how to get the two round rubber plugs through the hole? DK has a rebuild kit for my carbs for $72.
 

850Switchback

Active Member
Messages
154
Age
45
Location
CT
Country
USA
Years Snowmobiling
30
Snowmobile
2020 Switchback XCR
Your right on, I was thinking later models. You can still test the needle & seat the same way. Or maybe a leaking primer? Pinch the line or try a Mighty Vac.
I did the same, even wrote a whole response about Cat dealers selling the o-rings separate since Polaris doesn't, before I realized wrong carbs lol
Fuel pump looks good. In process of rebuilding. Any tips on how to get the two round rubber plugs through the hole? DK has a rebuild kit for my carbs for $72.
a very light coat of petroleum jelly and they should pop right in
 

George Majewski

New Member
Messages
9
Age
54
Location
LaCrosse, WI.
Country
USA
Years Snowmobiling
35
Snowmobile
99 xc 600
After much frustration, come to find that a drop of Dawn dishwashing liquid with a small allen wrench worked out very well for popping in those pesky rubbers. Gonna buy a carb rebuild kit and do them next year. Thanx to all.
 

George Majewski

New Member
Messages
9
Age
54
Location
LaCrosse, WI.
Country
USA
Years Snowmobiling
35
Snowmobile
99 xc 600
Turns out after riding today, after first start up I used a spring steel style paperclip, which didn't totally pinch off the primer line. It however does seem to be the culprit of the matter. Normally started on first or second pull after warmed up. My model has the choke as well. At this point I would think I could simply bypass the primer?
 

850Switchback

Active Member
Messages
154
Age
45
Location
CT
Country
USA
Years Snowmobiling
30
Snowmobile
2020 Switchback XCR
I don't see why not, it was just added as a cold start aid. The 97&98's didn't have a primer.
 

850Switchback

Active Member
Messages
154
Age
45
Location
CT
Country
USA
Years Snowmobiling
30
Snowmobile
2020 Switchback XCR
Have you tried Hudons in NY or Al's snowmobile in VT? not sure if there are any sled salvage yards closer to you
 

850Switchback

Active Member
Messages
154
Age
45
Location
CT
Country
USA
Years Snowmobiling
30
Snowmobile
2020 Switchback XCR
Dennis Kirk has either Parts Unlimited or SPI rebuild kits for those. That SUDCO link I gave you above has individual components available for order.
 


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