I originally posted the following problem in the Polaris RZR News thread labeled “March 2nd 2017 Recall Thread, Please Post any and all Recall Info /Questions Here” on March 11, 2017. I decided that this is a separate issue from that thread and I should not have sidetracked/hijacked it.

In July 2016, my 2015 RZR 900 Trail had the vent hose re-routed and heat shield replacement done per their last recall and Stop Riding notice. I never smelt gas fumes, pressure or vacuum when opening fuel fill cap, or had any backfiring before the recall fix.

I now smell fuel fumes while riding and experience extreme pressure release when opening the fill cap when I get back from a ride. The cap actually blows into my hand. I now fear a engine fire if that pressure vented itself into the engine/exhaust pipe area. My rework was done at a Polaris dealer in WI. I am thinking of drilling a 1/16 inch hole thru the fill cap to allow the pressure to release itself as a stop gap fix.

My friend has a 2015 900 XP. He had his reworked by the Polaris technicians at the 2016 May Polaris Rally at Moab, UT. He never had any issues before the FIX. Since then he also has pressure in the fuel tank immediately after a ride. He is concerned but not as alarmed as I am.

Here are the facts:
• Neither of us had pressure or vacuum fuel tank issues before the factory recall fix.
• Two of us are now experiencing pressurized fuel tanks after the fix.
• I cut a hole thru the plastic panel under the passenger seat to access the vent line connection.
• I removed the fuel vent line from the plastic elbow at the tank twice.
• Both times there was some fuel in the hose but the hose was not blocked.
• I haven’t tried blowing back into the plastic elbow tank connection.
• I don’t feel comfortable leaving the fuel tank cap partially ajar while riding.

Here are my thoughts:
• The tank vent has some kind of a check valve in it that separates vapor from liquid.
• That valve is stuck in the closed position; neither air can get in or out.
• That failure mode is time/age related and was not addressed by the 2016 recalls.
• If the RZR is being operated in a cold atmosphere (winter riding), the air pocket in the tank doesn’t expand, so as fuel is used, a vacuum occurs.
• If the RZR is being operated in a warm/hot atmosphere (riding in AZ @ 85F plus), the air pocket in an almost empty tank expands faster than fuel is being used and pressure occurs.

Here are my FIX ideas for the above stuck check valve:
• Replace it which is very difficult and will probably fail again. I don’t want to do this.
• Drill a 1/16 inch hole in the filler cap — Old lawn mowers and other small engines used to have a hole in the gas tank cover for venting purposes.

Here are my questions:
• What is wrong with my thinking?
• What should I try before doing any changes?
• Is anyone else experiencing fuel tank pressure/vacuum issues on their 2015/2016 RZR 900s?
• How would you attempt a fix?

All comments will be greatly appreciated.
LeRoy presently in the warm SW Arizona area

Utah RZR Rentals

whence