October 2017 Ask the Experts

Battery blunders, running rich and changing fuel lines.
Arctic Cat ZR 5000 snowmobile
2015 Arctic Cat ZR 5000
In the October 2017 issue, our experts answered our readers' questions about battery issues, alarming exhaust sounds and problematic fuel lines.

Battery Blunders

Q. Long-time subscriber - Love the mag! I have a 2015 Arctic Cat ZR 5000. I’m now on my third battery and still having issues with dead batteries. There’s only 85 miles on the sled, with no other issues at all. Any idea what may be the cause? – Chris G., Indianapolis, IN

A. Without seeing the sled, electrical issues are difficult to diagnose. Check the obvious first – are the key and kill switch always turned off when the sled isn’t in use (duh, right!)? Then check the wiring connections and make sure everything is grounded where it should be. If all that looks good, we’re inclined to think you’ve got a bad solenoid. You can test that fairly easily with a voltmeter. Obviously, if you’re not comfortable with performing this type of maintenance, your dealer should be more than capable of helping out. We’ve had solenoid issues before. It does happen, and it can ruin batteries or at least drain them quite quickly. Good luck! - Experts
2005 Polaris Super Sport 550 snowmobile
Polaris Super Sport 550
I’m Rich!
Q. I have a 2005 Polaris Super Sport 550. Sled starts ok (a lot better with new plugs), but does not want to idle unless given gas. Carb was cleaned, and I loosened the screws a half turn. I noticed a large noise similar to a gunshot that goes off a few seconds after it’s started. Any ideas on what the issue is? – Kali7312

A. The gunshot sound is from a backfire. That is caused by unburned fuel in the exhaust pipe or silencer that ignites there when the exhaust gets hot enough. Failure to idle is from being too rich at zero throttle (this ultimately is also causing the backfire). To diagnose this, start the engine and run it at idle or just above idle, and see if both legs of the Y-pipe are getting hot or if one is hotter than the other. This will tell you if one cylinder is extremely rich compared to the other one. You can also pull the plugs after idling it and see if one shows wetter than the other, and then you will know where to focus your efforts. Being extremely rich at an idle can be caused by a number of things. Here are the most common culprits:
1) Stuck or misadjusted choke cable. Check the choke cable and make sure there is free play in the cable when off, and that the plungers are dropping all the way.
2) Low compression. Using a compression gauge, check the engine compression. Low compression from a worn out top end (pistons and rings) can cause it to act rich.
3) Leaky needle and seat. Check the needle and seat in the carbs to insure they seal properly when the float bowl is full of fuel. A leaky needle and seat can make it act rich, as it will flow fuel continually into the engine.
4) Leaky fuel pump diaphragm. If the fuel pump’s diaphragm has a pinhole in it, it will leak fuel into the side that the impulse line is plumbed into.
5) Bad plug wire or cap. Inspect your caps for excessive carbon buildup on the inside contact point where the cap snaps onto the wire. Clean with contact cleaner or replace the caps and use dielectric grease on the top of the plug to promote a good connection. Screw the cap onto the wire in a clockwise rotation. If it rotates more than 1½ turns before coming tight, unscrew the caps and either replace the wires or cut ¼ inch off of the wire and re-install the caps. Inspect the wires for worn spots that can allow the ignition to arc through it. If you have bad wires, the resulting intermittent spark will make
it misfire and run rich.
6) Plugged exhaust. On older sleds, I occasionally run into a mouse nest in
the silencer that can cause a partial blockage and make the sled run rich. Usually they burn right out, but if the mouse carried nuts, dog food or something else into the exhaust, then you may have to clean it.

There can be other causes, but these are the most likely, listed in order of importance. With some simple troubleshooting, you should be able to
find the problem.
– Jerry Mathews,
Starting Line Products
fuel line diagram
Diagram of fuel line to gas tank
Pulling the Fuel Line
Q. We have a ’07 Ski-Doo 550 fan. How does one get the fuel line with the filter attached out of the tank? There is an insert at the top under the fuel fill cap that doesn’t seem to want to come out. This insert looks like it’s there to direct the gas to the back of the tank when filling. In order to unhook the fuel line to get at the filter, this insert has to come out. Or do you pull out the pressed-in fitting where the fuel line enters the tank in front? Then the line and the
filter attached can come out. Does this sound right? – Polaris500

A. You can remove the fuel line where it enters the tank in front. Pull out the male fitting (Part #21 in photo) where the line enters the tank. You should then be able to remove the entire hose assembly and replace the filter. I would suggest replacing the grommet (Part #22) on the fuel line inlet as well, just to ensure a tight seal upon reinstallation. – Jason Houle, Straightline Performance
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