85 Formula plus starting problem - Snowmobile Forum: Your #1 Snowmobile Forum

Rustybux · 01-15-2008, 04:12 PM

Rotax 521cc. Same as my other sled but this one is very hard to start if you let it sit for about 20 minutes or when it's totally cold. Rebuilt the carbs, new plugs etc. Plenty of spark. It will eventually start if I hold the throttle wide open and pull about 10 times on the rope.
My question is: When I hold the throttle wide open, is it letting more air in or sucking more fuel out of the main jet. I can't tell if it's flooded or not enough fuel. Priming does not help except make one plug wet and the other dry.
i'm totally confused. about to throw this machine away.

**smallengineguy** · 01-15-2008, 08:35 PM

There is obviously a fuel problem. I had that same sled, I primed it 3 times and it started right up. Once warm I did not need to prime it. If you have to hold the throttle open, it's getting fuel leaking by when it sits. You might have to replace the carb needle/seats.

upersleder · 01-15-2008, 09:46 PM

another thing is to check the primer. try crimping the lines and see if it helps. if it does, replace it.

Rustybux · 01-16-2008, 12:11 PM

What do you mean "crimp the lines"? You mean the fuel could be syphoning through the Primer and flooding the carb?

Rustybux · 01-16-2008, 12:14 PM

Smallengineguy? I checked the needle and seat when I checked the float level. Blow through the fuel inlet and hold the float up and I can't blow any air through it. When I hold the throttle wide open, am I leaning it out so it will start or letting the engine suck more fuel through the main jet? is it flooded or not enough gas when I hold the throttle wide open? thanks for your advice

JheLrey · 01-16-2008, 02:41 PM

My Brother has an Indy 448 trail. It will only run on one cylinder unless you add gas to it yourself. It is weird as hell. I rebuilt the carbs 3280973248347289X and still no luck. Checked lines, different fuel pump, etc. We gave up and just bought another carb. Does this answer your question? No, but I wanted to rant.

**smallengineguy** · 01-16-2008, 08:30 PM

Holding the throttle open is leaning it out. Once it has enough air in the mix, it fires. Crimp the primer lines just like you said, to see if fuel is getting by the primer.

SkiDooFormulaMX · 01-16-2008, 08:55 PM

im willing to get its your primer, my formy started 1st or 2nd pull everytime. id give it 3-5 primes cold, pull, fire and shut off, one more. and she ran like a champ.