Polaris Ranger Carb Problem?

Here is the story, Grandpa has a first gen I think its 10 years old polaris ranger 400cc. Problem showed up this year serviced it this past summer, about two weeks later said it wouldn't run right/start. Check it out the two week old plug is all fouled, clean it off with a torch and starts up, So I replaced the plug. Fine for about a month than the same thing. Alright decide to take carb off as all adjustment are sealed. open it up and the thing is spotless. clean it anyway, put back together and open the adjustments. Get carb back on everything seems ok.

well long story short through the last summer/fall he went through four more plugs. Nothing changed about his use, still uses the same fuel(we have a station that has one pump with pure gas yet, he always gets that) I called two differant dealers, one said they replace these carbs all the time, the other said they have only replaced two on the rangers(should of expected that )

Carb Is $500 any ideas on something I might of missed, may just have to do a carb. As a side note this thing from new never seemed to want to idle nice. Never needed the choke to start it but always had to step on gas to start it.

Thanks, Eric

Is the plug fouled from being rich or from oil? Too much oil? Blocked air cleaner, sticking choke. You may also have a weak spark. Check to see that the plug is the correct one, don't assume the plug is the correct one because it was in there, look it up, ask other users.

If it's a two stroke and has a reed plate, I would check that. Did you run a wire through all the little holes in the carb when you had it apart?

mozz wrote:Is the plug fouled from being rich or from oil? Too much oil? Blocked air cleaner, sticking choke. You may also have a weak spark. Check to see that the plug is the correct one, don't assume the plug is the correct one because it was in there, look it up, ask other users.

It seems like it goes rich at times. I know it is not oil fouled. Air filter is new, no restriction in the intake.

I do not think the choke is stuck cause you can pull the choke and tell it's loading up, then push it in and all returns to normal.

Doubt the weak spark , as it runs to good. I could bring the labscope home from work and take a look at the spark signature, but I doubt that is the problem. What would weak be anyway? How do you find Kv specs for something like that. will the coils on these things do 30-60Kv ?

Plug is correct, what the owners manual calls for.

It is a four stroke.

Keep the ideas coming

Eric

Coalfire wrote:

mozz wrote: will the coils on these things do 30-60Kv ?

Yes, around 50kv I believe.
Thats an awfull lot for a new carb, did you price around? Whats the model number of the carb?

Is the choke plate tight on the shaft? If the screws are loose, at higher air velocities the plate could be fluttering and it's possible you wouldn't notice since at those carb airspeeds, the engine is under load.

Are you running it slow a lot 10MPH or under or idling, maybe a hotter plug is needed.

If you fuel been in it for a long period, try this


http://www.amsoil.com/storefront/aqs.aspx?zo=1373080

I will have to check on the carb # don't remember off hand, I think its a mikuni.

As for the choke plate, this carb does not have that type of setup

Fuel is always going through it, not stale and it is pure gas not the stuff with ethanol. It is my grandpas for use on the farm, so of course most times it is under 10mph, but this problem happened all of a sudden, no change in anything.

Eric

Sometimes with off road machines, the needle & needle jet wear out from bombardment of abrasive dirt over the years, which makes it run pig rich in the midrange. Usually it will feel flat, & dump black smoke out the pipe at any range besides idle/low speed operation. The clearance is so small you'd never see it with the naked eye, although you'll usually see wear marks on the needle, or an ovaled needle jet in real bad cases. Not a guarantee, but a possibility.

I chased a problem like this on a TRX300. Same symptoms. Got tired of throwing money at the carb, so the owner replaced it with a chinese one off eBay. Has never run better. I never did find for sure what the problem was, but the only 2 things left were the needle/needle jet, & float assembly ( non adjustable because it was plastic ).

I worked on a Polaris 400.
One odity that should not be overlooked is the spark plug boot assembly just slips onto the wire and is replaceable.
Check if the wire has pulled from the boot some, just an 1/8 inch can hurt your spark.
If you have been changing plugs often it is eazy to jurk on the wire, when pulling off the plug.

Smitty, I am leaning towards the carb, what you said gives me some reassurance.

Shortbus, I will double check that plug wire

Thanks everyone, Eric

S, this post is from 2012. Real good info but a tad late. Welcome to the FORUM my friend. PS-check dates on posts in the future.

smith99 wrote: ↑

Wed. Jul. 26, 2023 2:04 pm

If your ATV has spark and fuel, there are a few things you can check to determine the cause of the problem. The fuel may be struggling to get from the tank to the engine. This could be due to a clogged fuel line, a faulty pump, or a blocked filter. Another possibility is that the spark plug isn't firing correctly. Or also check the Polaris Accessories if all doesn't work.