I've got a 2010 sportsman 500 that ran well for years then slowly started to become more and more difficult to start until no start.

I started by checking spark (it's there) then tracing fuel supply and noticed no fuel exits the fuel tank at top out of the nozzle by the sending unit. See pic.

I can get the engine to start briefly with starter fluid so know most all remaining components are working correctly.

Is there something I'm supposed to do to prime it or is sending unit (way expensive) toast?

Or is fuel pulled entirely by fuel pump vacuum and therefore fuel pump is out? :cowboy:

 

Can't remember.. It does have the same old fuel pump that all the others have. Do you have the inline red fuel valve leading from the tank? if so Ima thinking this went to the fuel pump top nipple(inlet) second nipple line(outlet) went to the carb,bottom(P marked nipple) was the vacuum line that went to the right side of the carb.

 

I found it.. I guess if the part in the tank is messed up? You can pull a vacuum with a mity vac on the carb vacuum line that goes to the pump and see if fuel is going through it. If it doesn't could be a fuel pump stopped up or something blocked in the tank?

 

Right, has a traditional airbox vacuum driven pump, as you pictured it. So that was my next attempt, to pull vacuum from the hose leading out of the tank to the red on/off valve before the fuel pump to see if it can be primed. If I can't, do you think this part twists off the tank? It looks like a large threaded lid with a metal L shaped fuel outlet and the fuel sending unit next to it. I guess the L shaped fuel outlet has a filter on the inside? I almost feel like just drilling a hole on the bottom of tank and connecting to fuel pump! Thanks.

 

I was kinda thinking about that red plastic fuel valve myself. You can remove it and check it out. As far as the cap on the fuel tank,I never tried to take one off as I didn't have a problem like this on one when I retired in 2011. It may unscrew or it may be glued down as some were. I'm kinda curious on this one also. If you can get fuel flowing out of the tank nipple then either a fuel valve stopped up or a weak fuel pump I'd think.

 

So I primed fuel out of the tank down to the fuel pump past the red valve (it works). Fuel flows out the output stem of pump when off. Turning engine over doesn't really increase flow any. Guessing this means pump needs replacement (or rebuilding but I'm not going there)? thanks.

 

Pumps are too cheap now to have to rebuild one.Amazon and ebay have aftermarket pumps low as 11 bucks versus over 50 bucks for an oem pump.

 

Here's the wrap up on the 2010 (and 1998) no start issue. It had spark and fuel, I thought. Pump tested weak, no real increase in fuel flow between engine off and cranking. Replaced pump, still no start (other than a few seconds on starter fluid). So here we go with carb cleaning. Attached are pics -all are before cleaning pics so everyone can see how little dirt/grime can clog carb passages/jets.

I ran into trouble with the fuel screw, removed plug then couldn't remove screw. I first went to close it to know how many turns out to go. It seemed almost closed, checked and double checked. So i proceeded to remove it, got stuck a turn or so out and couldn't turn it much back in, what a mess.

So I proceeded to clean rest of carb and put it back together. To my dismay it fired up after a few cranks to load fuel from pump.

I then felt inspired to work no my 1998 with no start yet fuel and spark. This one did have a nice fuel stream when cranking engine over.

It has the older 34bst carb. I was not able to remove the slide as one of the screw heads broke off, great. Other jets came off ok and cleaned up. I replaced nothing, because the kit costs nearly $42 and a cheap carb is $48, so i figured let's roll the dice.

Well it too fired up and it took me 2 tries to set the fuel screw right, i'm at 600ft and it took exactly 2 turns out. I learned simply loosening the front/rear carb clamps allows me to twist the carb 90 degrees, enough to get a straight screwdriver in there as even a flexible carb driver was too long for the tight spot.

Yeah I got lucky, I'll take it for now. Thanks for all your help! :cowboy:

 

Glad you got em running ok. As far as the plastic jet block that the screw head broke on,I never pulled them out unless they were galled up and needed to be replaced.Next time you need to tear into a carb you'll be a pro..

 

I took out the jetblock on the 2010 to get the needle jet out to flush it with electrical cleaner, I like how fast that stuff dries. The 34bst (1998) doesn't require getting the jetblock out to get to the needle jet, it's right under the diaphram. I kinda like the ease of cleaning the 34bst better and both quads hit 58mph!

The hardest part of both carbs was putting it back into the engine intake. So I put a small 1x4 over carb intake, then put a 2x4 that almost reached the rear seat frame where I then used a pry bar to push the carbs into the intake. Fun, fun! :cowboy: