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Small Cabin Forum / General Forum / Need ATV repair suggestions
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# Posted: 9 Apr 2024 15:34

2007 550 Sportsman EFI. Bought this wheeler about 2 years ago for my son and since i've owned it, it's had a slight idle problem when cold. But it always started and ran well. However, my son rarely rides it...we've maybe put on 100-150 miles on it since we've owned it.

Last fall we went up to the cabin and went to fire it up and it took a bit to get her going. Had to crank it several times and give it throttle while cranking to get it to fire. Then had to stay on the throttle a bit once it was running to keep it going. Just figured this was because of the months it had been sitting for (but always hooked up to the battery tender). So we did about a 40mi ride and came back.

Went to start it to move it again and it wouldn't start. It'll turn and turn and turn, and occasionally backfire but it would never start. I popped open the air filter box to check that only to find it packed pretty tight with a mouse nest...and a dead mouse. I don't know how, but somehow the mouse got in there without chewing through the box or through the air filter. It did some Houdini witchcraft or something. Anyways, cleaned it out and still no luck.

Pulled the plug and it was fouled a bit, so i put a new one on and confirmed it had plenty of spark. I also check to make sure gas was flowing to the engine and also when the plug was out i turned over the motor and puffs of gas misted out of the spark plug hole. Still no luck. I also confirmed that when the key is turned on the gas pump is running. Also confirmed that when i turn the rig off i can feel the IAC is turning/working.

So i'm stumped....what do i try next? Was hoping to fix it while it's up there vs. hauling it home. Any ideas?!

# Posted: 9 Apr 2024 19:27

EFI can be a bit tough. They can still run like crap with old gas though. Sucking in a mouse nest isnt going to help any issues. Was there any mouse evidence on the throttle plate? If so I would do a compression test if your gas is new. But for a cheap easier check make sure its engine cut off isnt on and it's in park or neutral if it needs to be.

You need a few basic things to make a engine fire. Fuel, compression and spark.

I had my own issues with a 2008 rzr 800 efi. It would fall on its face after about 3/4 throttle. Turns out I had bad gas, semi clogged in tank fuel filter and a shift location problem..of it dosnt know what gear it's in it wont let it rev out.

# Posted: 13 Apr 2024 22:08

Did any debris from the mouse's nest get stuck further down in the tube between the airbox and the engine? I would check that if you haven't. Maybe airflow into the cylinder(s) is blocked.

# Posted: 13 Apr 2024 23:40

I would do the checks suggest above. Make sure no debris got sucked down the throttle plate (or past).

If that is a no, then I would lean towards a fuel problem (maybe filter). While spinning it over have someone shoot a shot of carb cleaner down the intake. If it fires and runs for a second or two, then its fuel delivery.
(NOTE - Do not keep using carb cleaner as it can be VERY hard on the engine. Just use it as a diagnostic tool once).

Check fuel filter. Also check for water in the fuel. Disconnect the fuel line at the throttle input and drain some fuel in a clear water bottle (1/2 bottle worth). Look for water.

# Posted: 14 Apr 2024 10:39

Do yourself a favour and start with fresh gas. You can chase a lot of potential issues that all come down to bad fuel.
Do the simple things first. If it starts on fresh fuel run it for a bit to flush the system out before doing anything else. Some sea foam in the fuel won’t hurt and might help if it’s a dirty fuel system

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