Mule 610 started blowing white smoke

[laurencen]

looking for a few ideas, have a 2016 mule 610, it has 150 hours and ran like a top from new never had any issues changed oil yearly, today first run of the year, started fine but idle was slower than normal, running around the yard half throttle fine but under load on hill and full throttle lots of white smoke oily smell, every time its accelerated or hills.

it was late but this is what Im seeing, it idles poorly and dies, oil seems to be way over full and clean, it idles great with dipstick off but throws oil out motor, gas tank was under pressure when opened, do not recall this any time we fill it.

have to find a service manual, drain the oil and see if there is a vent for gas tank plus breather for motor, mice are bad here and hoping its something simple

 

[Bill Guenthner]

“First start of the year”

I try to start everything at least once a month. Hopefully it’s just bad fuel. Did you have stabilizer in the fuel?

 

[laurencen]

new fuel made no difference its white smoke lots and oily smell, with temps of -40 starting over winter is not a option, my thought is with warmer weather and fuel tank pressurising somehow gas got into the oil, may explain how the oil is now way past full, will be changing oil today and figure why the tank is not venting

 

[Zebrafive]

air cooled, or liquid cooled? white smoke sounds like coolant being burned, but not if air cooled?

 

[laurencen]

this is a air cooled unit, no coolant, still questioning the pressure in the gas tank, figured there is a vent to prevent this,

 

[ROUSTABOUT]

Clean crankcase vent.

 

[mike0000]

Does the oil smell like gas, real thin when you drained it? I have an old troybuilt tiller that the float sticks open occasionally, results in lots of gas entering the crankcase.
Id drain the oil, refill and see how it runs.

Mike

 

[Bill Guenthner]

new fuel made no difference its white smoke lots and oily smell, with temps of -40 starting over winter is not a option, my thought is with warmer weather and fuel tank pressurising somehow gas got into the oil, may explain how the oil is now way past full, will be changing oil today and figure why the tank is not venting

If you left fuel in the carburetor bowl at those temps you probably need to rebuild the carb.

 

[laurencen]

to answer the above we leave the fuel in every winter and never have a issue, I have had a mule 550 and it still runs today as it did from close to new unfortunately its not quite the same fuel setup,

oil is real thin and when drained we measured 1 25 liters, that's more than recommended, full including filter is shy of one liter and it has a odor to it

have to look for the crankcase vent tonight, missed that one what would I be looking for, my manual has nothing on it just like this odd plastic valve.

anyway today, drained the oil, looked at the fuel pump and it was bad so installed a new one tank still pressurizes if left for half hour so the tank has two hoses coming from it, front goes to filter then pump, the other has a short hose then a plastic (sort of valve) then to the charcoal canister, canister has 2 hoses on top onw from the tank the other to the intake manifold, there is another larger hose off the bottom runs to the tank area with a fuel filter to prevent dust entering then open below the seat.

all lines are clear after the odd plastic valve, no idea what it does but it has a red end and black body, as it is it allows free flow from the canister to the fuel tank but restricted flow from tank (hard blowing with my mouth) to the charcoal canister, Im guessing it should vent the tank pressure but it is not.

trying to find one of these valves, dealer has it backordered till June, has no idea how it works or what it does, removing it the fuel tank does not pressure, unit will run 75% throttle for a half hour but full throttle it bogs down and dies has a distinct odor no smoke but when you slow down and let the fuel catch up, if you open the gas cap it runs 75% no issue at full throttle after a few mins it slows maybe 10% and will continue at that no issue.

anyone know what this valve does, by chance anyone got a mule with one of these on and willing to take it out and see what direction or flow it gives?

one final observation, the hose from the bottom of the carbon canister that runs to the front of tank and has the filter on it, when the mule is running and one sucks nothing changes but blow the motor slows and dies.

thats as much as I can figure, maybe the fuel bowl is set ow but ran fine when stored last winter.

 

[Bill Guenthner]

answer the above we leave the fuel in every winter and never have a issue

It “ran fine” when you parked it, but you’re sure it’s not a fuel or a carburetor issue. Maybe it just lost the will to live.

 

[laurencen]

new fuel made no difference, new pump was needed never heard of anyone draining the carb and tank for winter, could it be carb? maybe,

 

[Zebrafive]

The fact it does not run well at full throttle, sounds like partially plugged main jet. If you go into the carburetor that's one thing I would check.

 

[laurencen]

regarding the main Jet, as this machine will run full throttle for a minuet or so before slowing I was assuming the carb was good and more a supply issue, figured a carb issue its continuous, from what my service manual has for information all this vent carbon canister stuff is a Canada only setup, either way have it running 75 to 80% fine, it will work until the small plastic valve comes in some time in June

 

[Zebrafive]

California versions have the cannister. The fuel system has sealed fuel cap, not vented. The cannister is for emissions/prevents fuel vapor getting in the air. The plastic valve, black, red end is a check valve. I am not sure which direction it goes. You mention another line from the cannister with a filter in it. Where does this line go?

 

[Zebrafive]

What year is your Mule? Parts drawings show different fuel pumps for different years and also hook up looks different. Some lowest fitting goes to tank, others to carb. Maybe you have the wrong "new" pump?

 

[Zebrafive]

As test, I would connect the hose from the air intake that goes to the cannister to the hose from the cannister to the check valve, to the fuel tank. I would position the check valve to allow flow into the fuel tank. This will bypass the cannister and filtered air would be able to enter the fuel tank as fuel is being used.

 

[s219]

This is a classic "making oil" situation. Something is causing fuel to get into the crankcase. There are a wide range of causes, from simple to complicated. Sounds like you are working through some of the simple ones.

If this happened after extended storage with no effort to prep carb or fuel system, then simple issues would be high on my list. #1 would be a stuck float or blocked tank return line (if it has one).

 

[laurencen]

the connections on canister never have changed, one goes to the intake, one has a hose and goes over the fuel tank, has a fuel filter then a hose thats open sitting between fuel tank and front right of seat panel, assume its a breather.

as for the fuel pump, its the right one from dealer, identical the original pumped fuel but allowed it to flow back I could blow air both ways inlet to outlet, the new one only one way

Im still leading to that check valve, this one free flows air to the tank but needs pressure to go from tank, its what is holding pressure in tank, eta for a new one is 3rd week June

it is running close to 80% full throttle, full it still bogs like its out of gas after 60 seconds, will recover if throttle is reduced, maybe had a couple issues and float in carb low? this weekend have to pull the carb and check that

have a great weekend to all

 

[laurencen]

it has no fuel return, my thought on float stuck if up no fuel could get thro to run if stuck open it would keep dumping fuel to intake, would idle erratic or high

the carb is my next task on the list

 

[Zebrafive]

You need to find out how/why the fuel tank is being pressurized.
Only two sources. The cannister or fuel pump.
If you disconnect the cannister at the check valve, the check valve should let the tank take in air as the fuel is used, but not allow air out. If the tank still becomes pressurized, it has to be the fuel pump. If not, problem is with cannister system