Mystery mower fuel problem

[sportbikerider78]

When this problem happens and the filter goes dry, what happens if you pull the filter off? Is fuel freely flowing? It would seem that it is not and that would point me towards your tank and/or fuel line.
Have you pulled the line and drained the tank yet?

Lawn mower carbs are so easy to access, I'd pop the float bowl off and blow it out with compressed air, and then hit every little nook and hole with carb/choke cleaner.

A good carb clean is easy insurance.

 

[begreen]

The tank has been drained twice. Everything including fuel lines, filter and carb has been replaced. I have carb cleaner and will try it, even though this carb is brand new and has the exact same symptoms as the old one.

 

[rustynut]

when it happens again also check the spark.......

 

[semipro]

I have noticed that many fuel filters never "fill" and that fuel will still flow through fine even though air is trapped inside.

 

[begreen]

The mower runs great and starts right up again if I wait 10 secs for the fuel filter to refill. I'm going to replace the filter with one from Kohler that lists for this motor. I note that this is a 51 micron filter. Some are as fine as 15 micron.

 

[rustynut]

also had one that had heat shields fallen off and when the temp & humidity was just right the carb would frost up and get real silly to the point you would stop driving it. Then after a while while you were scratching your head it would thaw out and things would be fine......until the next time weeks later.......that was a tough find
rn

 

[begreen]

Until I can get the proper 51 micron Kohler filter I will just fill the tank. I did that last night and cut tall grass for an hour in our hilly side field. The mower ran like a charm and still had 1/2 tank left.

On a different but even worse note my splitter won't run for more than a minute. It has a Honda 5hp motor. I pulled the sediment bowl off the fuel valve and it is just filling a drop at a time. Ugh, this one does not look like fun to take apart. Anyone know of any tricks? Is this a case for Seafoam?

 

[blades]

well if it isn't draining from the tank through the filterthen replace the lines and clean the tank with solvent.

Just had another mystery mower problem - big commercial zero turn about 7 years old- just had it in shop last week for a frozen clutch and the week before for a blown fuse( didn't know at the time of the fuse that it was a symptom of the clutch going out , I just fix them don't run them) anyway customer calls up mower hesitating sometimes dying out doesn't seem to respond to throttle or is late to the party, course he tells it's fuel injected ( no its carbed) anyway after a bit of looking 2 of the 4 bolts that hold the carb and intake assembly on are missing in action and the other two are loose ( factory install never been apart) - hence massive air leak- cause of problem. What rattled those bolts ( 8mm dia x about 3" long) loose and out no idea , unless not installed correctly to begin with.

 

[johninwi]

Assuming the outlet is toward the front of the tank, is the motor is running rough by chance? might be if it's running rough and the tank is being shaken more then the fuel is "bouncing " around inside and not flowing? The gas is airaited? How do the plugs look? Might be time for a tuneup. Would be a longshot but you've covered everything else.
When you swapped carbs do you set the float so the carb filled completly?
Or maybe just mow the hill first?

 

[begreen]

well if it isn't draining from the tank through the filterthen replace the lines and clean the tank with solvent.

Just had another mystery mower problem - big commercial zero turn about 7 years old- just had it in shop last week for a frozen clutch and the week before for a blown fuse( didn't know at the time of the fuse that it was a symptom of the clutch going out , I just fix them don't run them) anyway customer calls up mower hesitating sometimes dying out doesn't seem to respond to throttle or is late to the party, course he tells it's fuel injected ( no its carbed) anyway after a bit of looking 2 of the 4 bolts that hold the carb and intake assembly on are missing in action and the other two are loose ( factory install never been apart) - hence massive air leak- cause of problem. What rattled those bolts ( 8mm dia x about 3" long) loose and out no idea , unless not installed correctly to begin with.

RE: The Honda GX motor on the splitter. I don't think there is a filter on this tank unless it is at the fuel pickup tube. Could be a screen there but it would have to be tiny. The pickup tube looks to be about 4mm across. What solvent is safe to use for the tank and hoses, yet effective.

@johninwi as long as there is fuel the motor runs fine, it just isn't getting the fuel fast enough. I comes out at about a drop every 2 seconds out of the fuel shut off valve if the sediment bowl is removed.

 

[maple1]

On a different but even worse note my splitter won't run for more than a minute. It has a Honda 5hp motor. I pulled the sediment bowl off the fuel valve and it is just filling a drop at a time. Ugh, this one does not look like fun to take apart. Anyone know of any tricks? Is this a case for Seafoam?

Is the fuel valve/bowl (petcock?) removeable? If so, time to do that. There may be a screen on there inside the tank that's plugged or gummed up. One of the kids motorbikes had that happen a couple years ago - it was nasty in there.

Seafoam is usually my first try when things like this happen - that way at least it'll clean things up some for when you have to take things apart if it doesn't work, and it's easy to do. But when it's a total or near total blockage, I usually go right to taking things apart.

 

[begreen]

It looks like the valve is integral with the carburetor. I'll get some seafoam today.

 

[begreen]

I bit the bullet and got to work on the splitter today. The grass is browning out and can wait until Sept. at this rate.

I narrowed the issue down to the fuel shut off valve. Fuel flowed freely from the tank out of the fuel delivery hose. I took apart the valve and found a bit of varnish built up under the rubber valve seat. I carefully scraped it out with an awl, then carb cleaned it, scraped again, cleaned again until there was no more residue. I also carb cleaned and wiped the rubber valve seat clean a few times. Put it together and I was now getting about 3 drops a second heading into the sediment bowl instead of a drop every 2 seconds. Put it back together and it definitely ran better and longer. Only stalled once, so I added an ounce of Seafoam to the tank and ran it for another 30 minutes. Seems fine, I split up a bunch of alder and wild cherry without a sweat and no more stalling. At the end of this splitting season I will add another ounce of Seafoam to the last tank and will run the tank dry.

 

[jebatty]

Had the same issue with my wood splitter and a small B&S engine, gravity feed, no fuel filter. Never solved the problem other than keeping the fuel tank full.

 

[maple1]

I bit the bullet and got to work on the splitter today. The grass is browning out and can wait until Sept. at this rate.

I narrowed the issue down to the fuel shut off valve. Fuel flowed freely from the tank out of the fuel delivery hose. I took apart the valve and found a bit of varnish built up under the rubber valve seat. I carefully scraped it out with an awl, then carb cleaned it, scraped again, cleaned again until there was no more residue. I also carb cleaned and wiped the rubber valve seat clean a few times. Put it together and I was now getting about 3 drops a second heading into the sediment bowl instead of a drop every 2 seconds. Put it back together and it definitely ran better and longer. Only stalled once, so I added an ounce of Seafoam to the tank and ran it for another 30 minutes. Seems fine, I split up a bunch of alder and wild cherry without a sweat and no more stalling. At the end of this splitting season I will add another ounce of Seafoam to the last tank and will run the tank dry.

So - I wonder if there's a correlation to your mower problem? Two motors same fuel? Could be some varnish buildup on the mower tank outlet that is restricting fuel just enough when there is not enough fuel in the tank above it (head) to push it through?

From my experience with it, a varnish problem is just the thing Seafoam is made for.

(Also, not sure it's proper or not, but when I'm pretty sure I have some varnish/buildup that needs cleaning out, I usually double up the prescribed Seafoam ratio for the first tank through).

 

[semipro]

Interesting info on Seafoam here: (broken link removed to http://hildstrom.com/projects/seafoam/)
Its about $60/gal. off the retail shelf.

 

[sportbikerider78]

I bit the bullet and got to work on the splitter today. The grass is browning out and can wait until Sept. at this rate.

I narrowed the issue down to the fuel shut off valve. Fuel flowed freely from the tank out of the fuel delivery hose. I took apart the valve and found a bit of varnish built up under the rubber valve seat. I carefully scraped it out with an awl, then carb cleaned it, scraped again, cleaned again until there was no more residue. I also carb cleaned and wiped the rubber valve seat clean a few times. Put it together and I was now getting about 3 drops a second heading into the sediment bowl instead of a drop every 2 seconds. Put it back together and it definitely ran better and longer. Only stalled once, so I added an ounce of Seafoam to the tank and ran it for another 30 minutes. Seems fine, I split up a bunch of alder and wild cherry without a sweat and no more stalling. At the end of this splitting season I will add another ounce of Seafoam to the last tank and will run the tank dry.

Leaving a tank dry is a great way to get condensation and rust. Get some ethanol free gas if you can get it. Add some stabilizer and fill the tank to the brim.

With stabilizer, gas is good for at least 6 months.

I have stored motorcycles with full metal tanks for up to 2 years using this method. Zero issues.

 

[Highbeam]

With stabilizer, gas is good for at least 6 months.
I have stored motorcycles with full metal tanks for up to 2 years using this method. Zero issues.

Me too. Tank full of stabilized gas for storage. If equipped with a fuel shutoff valve I shut it off and run the carb out. Then roll the piston to TDC and leave it dormant.

 

[begreen]

Good to know, thanks. Only the splitter tank is metal and I may go a year before using it again. All the others are plastic. I put stabilizer in the mower tank, but run the trimmer and leaf blower (2 cycle) dry.

 

[begreen]

Ran the splitter for a couple hours today. I think it is running better now than it has for the past couple years. The motor purred like a kitten no matter the load. It looks like the shutoff valve cleaning plus seafoam treatment really worked!