Quad Runs rich suddenly?

[supton]

So my 4 wheeler gets used to push snow at the moment. Ran fine one weekend, parked it. It snowed again and so I went to go move some heavy slush and it wouldn't run--kept bogging down, would not do more than idle. Checked the plug and it was black--replaced it maybe a year ago, it's got like 20 miles on it. New plug did nadda so I yanked the carb and threw a parts kit at it. Wasn't that dirty, I was expecting worse, but a couple of jets did have garbage in them. Put back on and now it runs good. Drove it out of the woods and it floods out. Let it sit and now now it has this pattern of starting without choke, then acts like it floods out as warms up, if left to idle. Not that I've done it many times but that's what it's kinda acting like. It'll slow down at idle, goose it carefully, as it clears out I can then rev it like normal--let it idle and it seems to load up.

The vacuum operated fuel pump holds pressure; no fuel coming out. I had swapped out the petcock for one that wasn't vacuum operated, and I think the problem may have originated there--I haven't been switching to off when parking. I'm starting to wonder if it didn't flood while sitting.

I dipped a rag into the engine oil and it sure smells like gas. So I'm starting to wonder if it's just inhaling the gas from the sump as it warms up? I'm not finding anything else wrong, like plugged intake or exhaust. For the record I don't see any blue or black smoke, just normal white-ish as it warms up.

Try an oil change and hope for the best? Could it be gas-saturated oil? The oil is Rotella T6 and it has like 20 miles on it--I don't run it off road, it lives a gentle life, but it does seem many "cold" starts I guess, lol. Still looked very clear. I haven't been able to disconnect the crankcase breather, it's kinda buried and it's kinda cold right now.

Machine is a '94 Suzuki Quad LT-4WD with like 870 miles on it.

 

[kawie_guy]

So my 4 wheeler gets used to push snow at the moment. Ran fine one weekend, parked it. It snowed again and so I went to go move some heavy slush and it wouldn't run--kept bogging down, would not do more than idle. Checked the plug and it was black--replaced it maybe a year ago, it's got like 20 miles on it. New plug did nadda so I yanked the carb and threw a parts kit at it. Wasn't that dirty, I was expecting worse, but a couple of jets did have garbage in them. Put back on and now it runs good. Drove it out of the woods and it floods out. Let it sit and now now it has this pattern of starting without choke, then acts like it floods out as warms up, if left to idle. Not that I've done it many times but that's what it's kinda acting like. It'll slow down at idle, goose it carefully, as it clears out I can then rev it like normal--let it idle and it seems to load up.

The vacuum operated fuel pump holds pressure; no fuel coming out. I had swapped out the petcock for one that wasn't vacuum operated, and I think the problem may have originated there--I haven't been switching to off when parking. I'm starting to wonder if it didn't flood while sitting.

I dipped a rag into the engine oil and it sure smells like gas. So I'm starting to wonder if it's just inhaling the gas from the sump as it warms up? I'm not finding anything else wrong, like plugged intake or exhaust. For the record I don't see any blue or black smoke, just normal white-ish as it warms up.

Try an oil change and hope for the best? Could it be gas-saturated oil? The oil is Rotella T6 and it has like 20 miles on it--I don't run it off road, it lives a gentle life, but it does seem many "cold" starts I guess, lol. Still looked very clear. I haven't been able to disconnect the crankcase breather, it's kinda buried and it's kinda cold right now.

Machine is a '94 Suzuki Quad LT-4WD with like 870 miles on it.

Sounds like the choke may be sticking on to me.
If the oil smells like gas, I would change it once you get the carb issue found and fixed.

 

[supton]

I don't think the choke is sticking. I'm not sure how the choke works, actually, as it's not a separate butterfly. I do know that as I engage the choke (while running), it will idle up and then bog out--if I try to start with full choke it will quickly act like it's flooding out.

 

[Warstud]

Clean the carb and replace the float, needle and seat

 

[supton]

Clean the carb and replace the float, needle and seat

Did that as part of the carb rebuild. Kit didn't come with a diaphragm (for the slide valve, or whatever it's called) but it had the jets, o-rings etc. Ran much better afterwards.

 

[mk378]

The choke is a liquid valve that dumps additional raw gas into the intake when open.

It does really sound like the needle valve isn't closing. This will be worse at idle. Driving at throttle you're using the gas faster than it leaks in.

Also you've probably taken it apart enough to find this already, but make sure the air cleaner and air intake pipe is clear of mouse nest etc.

 

[supton]

Yeah, I did find some junk in the airbox, and a puddle of oil, so I think the breather/drain must be stopped up. Stupid mice! No change with the airbox left open though, and the air filter was not very dirty at all. I tried running without a filter, and it still seemed to be doing it.

Sounds like I need to remove the carb again, and check on the choke circuit. It's a bit of a pain to pull out, access is somewhat limited and the carb is suspended on rubber hoses, not metal runners. So cold hoses are hard to compress and move out of the way. I'll have to look this time and see if the airbox can be removed, that would free up quite a bit of space.

 

[Warstud]

I had swapped out the petcock for one that wasn't vacuum operated

Maybe the problem right there.

 

[supton]

Maybe the problem right there.

That is what I am thinking--maybe the needle quit. I am not sure how restrictive the fuel pump is, in the off state doing nothing. Fuel petcock is below the carb, along with the lowest part of the tank, and I rarely fill over half tank. Fuel goes out to just above the front axle where the pump is, then gets pumped back to the carb. I wouldn't have thought gravity would have pushed fuel, but maybe it had enough fuel to push.

 

[tmorris1]

I would also drain the gas and start fresh. May have got a bad batch or a bunch of water if you seldom drive it. Use something without ethanol if you aren't using it much.

 

[tmorris1]

I would also check the vacuum line to the petcock to see if it is leaking fuel into the vacuum line. I don't understand how or why a petcock would be vacuum operated? You sure it isn't a fuel pressure regulator? Either way a fuel to vacuum leak would make it run like crap and very rich.

 

[supton]

Not sure where I'd get non-ethanol gas.

I removed the vacuum operated petcock already. When I bought it, it had been sitting for several years. Did a bit of research, sounded like the fuel pump and petcock were common points of failure. The fuel line on mine was full of white junk, so I replaced all the fuel lines and converted to a standard non-vacuum operated petcock at the same time. The fuel pump is still vacuum operated though.

I checked and the vacuum line to the pump is holding a vacuum; it is not sucking in gas from there.

It snowed this week so I tried it out. I got about 5 minutes of plowing before it would no longer idle. Haven't had the desire to work on it, I've been working extra hours lately and it's the dead of winter to boot (winter blues).

What I don't get is why doesn't it blow black smoke? The plug is showing carbon fouling. The quad, if left to idle, starts to bog down; if I carefully goose it, I can get it to clear out, then it would rev up. But if it was flooding it should be blowing a cloud of black when it either burns off some liquid gas or otherwise decarbons itself. it hasn't done that. It's weird.

maybe this weekend I'll get the gumption up to work on it.

 

[tmorris1]

Did you by any chance screw the fuel screw in or out accidently when taking the carb apart?

 

[dblshock]

fuel filter.

 

[supton]

Did you by any chance screw the fuel screw in or out accidently when taking the carb apart?

It was running badly before I touched anything.

fuel filter.

It's an interesting idea. I think there is a screen on the petcock, which means me filling the tank is something I know regret. I don't recall there being another filter. Are you thinking that when I gun it, the increase in vacuum pulses enables the fuel pump to work harder against a restriction? But why would the plug get black? yet no black smoke...

 

[thastinger]

sounds like the float is sticking open

 

[supton]

I did have to reuse the float, and come to think of it, I don't recall checking it. Oops. That does make sense. Wonder what a float costs (oddly it did not come with the carb kit).

 

[dblshock]

if its fuel just go right down the line starting with fuel, line, filter ect. my last two ATV issues were filter.

 

[IndyIan]

Is there an "off" on your fuel petcock? My 2000 has prime, reserve and, on. I get some weird fuel starvation stuff going on when running hard below maybe a 1/3 tank, so I keep it fuller than that. Here's a good youtube channel for these quads, I think he lives just north of me somewhere. https://www.youtube.com/user/Schneids15
Here's his video on carb cleaning, may help.

 

[supton]

Yes there is an off, I've not been using it, been lazy. Just ordered a float and will wait for that to come in. Once it warms up a bit maybe I'll yank the carb and check it out, it was like +1F this morning so I'm even less motivated to work on it right now.