Snowmobile Forum banner

1 - 15 of 15 Posts

·
Registered
Joined
·
5 Posts
Discussion Starter #1
I have a 98 Powder Special 600 EFI

Snowmobile is completely stock.

And here is the problem:

In a previous season, I lightly rolled it on hard snow; nothing was damaged EXCEPT a hard chunk of snow did manage to bust the handle bar kill switch. SO it has been unplugged and the sled ran fine for 2 seasons after that. (ive mentioned this to explain that i dont believe the problem below is a TSS problem)


This season however, I fired up the sled and headed off down a trail... it ran great like it always has, plenty of power, no monkeying in the RPMs or anything..... until about a 30minutes later while casually crossing a field, the throttle started cutting out like the sled was running out of fuel. BUT it wouldnt completely cut out. While cruising the sled would suddenly bog right down to practically an idle then all the sudden the sled had normal power again. Travel another 200m, then it would repeat, but sometimes during the process it would back fire.

So i managed to get her home, but the occurrence of this bogging kept increasing more and more to the point when I got her home, the sled would be lucky to travel 15 feet.

SO here are the symptoms:

-As far as I can tell, the sled is firing on 2 cylinders, even during the bogging.
-The sled almost always fires up within 2 pulls and idles normally
-The sled only bogs when enough throttle is applied to engage the belt and start moving the sled forward.
-While bogging, if the throttle is still applied, the sled will bog to the point of dying; and possibly backfire during the process..... BUT while bogging, If the throttle is released, the sled will return to a normal idle most of the time.
-During the rare circumstance that the throttle is applied and the sled moves forward without bogging, during this moment the sled will have 100% power potential, itl go as if normal, but usually only for about 75m before bogging again.

Heres wat ive looked into:

-It has fresh spark plugs, there usually dirty due to the bogging, but they still spark i believe
-The kill switch which i believe is part of the throttle safety circuit is un plugged
-The 2 intake disks in the gas tank dont appear to be plugged, but have been temporarily removed regardless encase their the problem
-I tested the fuel pump, and it appears to produce and excess of 60psi under 12v power
-The gas regulator has been removed, and blown out, after blowing it out, it appears to function at around 40psi, but it does look very old, and it may be sticking after being left alone for a while so idk.

What would u guys recommend ? the problems been a real head scratcher for me.

Any incite and solutions will be greatly appreciated :)
 

·
Registered
Joined
·
124 Posts
Sounds pretty much what my '98 ZL500 was doing. I thought it was the TSS, unplugged that and it still happened. Then I thought it was the stator, but it was an intermittent problem so I pretty much ruled that out. So I was reading up on 2 stroke engines and how to read spark plugs and from what I read my sleds symptoms indicated a lean condition. It would also start every time in two pulls and idle fine, it would miss at WOT and sometimes out of the blue idle backfire and refuse to accelerate. I would sit and idle for a minute and it would take off again, albeit running a bit rough.

I had the air-fuel mixture set at the stock position of one turn out, so I turned them in a half a turn and after riding nearly every day for 2 weeks (short rides) it is running perfectly and still starts easily. Not sure if I have another issue causing it to run lean, but it is working so far, so I will leave it alone.
 

·
Registered
Joined
·
5 Posts
Discussion Starter #3
Interesting, is the air fuel mixture just a carb thing ? or are u able to somehow adjust that on a fuel injected as well ?
 

·
Super Moderator
Joined
·
17,006 Posts
It's a carb thing.

60 psi seems like a lot, maybe you want to look into that a bit further. KCCats has done some work on those EFI sleds to reduce fuel pressure, maybe he will chime in.

Welcome to the forum!
 

·
Registered
Joined
·
24,890 Posts
Welcome!
Yeah this is puzzling!
Typically The fuel pressure should be 36si.
I have found that as the Cat EFI ages the diaphragm gets stiffer and it increases fuel pressure.
But in this condition it is too rich!

Simply get a gauge and a T and fuel hose, and test the supply side of the fuel rail (clutch side)
If you were close to me I would let you use mine!
 

·
Registered
Joined
·
711 Posts
SOP..ohm stator on those models.
 

·
Registered
Joined
·
5 Posts
Discussion Starter #8
Going to try a new Diaphragm this weekend....... cus i cleared it out once before and reinstalled it, much to my surprise the sled ran normal after that for about 2 km then it all went to hell again lol. Coincidence ? i hope so.

If that fails I may look into poor grounds cus ive noticed a few rather rotten wires on the sled. Maybe ill also see if i can check the computer code LED. Ive read its located on the bottom of the computer ?? does it just cycle the code over and over again while the sled is running ?
 

·
Registered
Joined
·
5 Posts
Discussion Starter #10
Been reading through the comments here and have noticed ive sort of mislead u on the fuel pressure! By 60psi , I mean thats wat the fuel pump produced removed from the tank and on its own circuit (not hooked up to the sleds fuel rail). Not sure what the pressure in the fuel rail is yet ..... i havent tested it :/ And I got confused by mixing the word Diaphragm with the Gas Regulator located on the end of the fuel rail. I pulled the Gas regulator out earlier and blew it out with air, then I gave it a measured amount of air pressure and it seems to pop at around 40 psi..... so maybe not the spec 36psi but pretty close. However the suspicious thing that I mentioned previously is after doing that and re installing it the sled drove normal for about 2km then went back to running FUBAR. SO I went to a dealer to buy a new Gas regulator expecting it to be maybe a $40 part.......... $380 Canadian :O !! so now idk
 

·
Registered
Joined
·
3,538 Posts
Pour some ISO-HEET in the gas tank and see if it clears up. My knee-jerk reaction is water in the fuel.
 

·
Registered
Joined
·
24,890 Posts
I make up an adjustable fuel pressure regulator that is complete with gauge!
And you can fine tune your EFI!
 
1 - 15 of 15 Posts
Top