Gravely almost stalls... reason? Things to check?

[PatasColo]

I don't know a whole lot about engines, so I thought I'd try you all. I have a Gravely Commercial 10a (walk behind tractor) I use to do mowing with a 40-inch front mower. Kohler 10-hp engine I believe.... aircooled only.

Yesterday was a hot day, I had been mowing for about 2 hours, and then the engine started to slow down and sound like it was about to stall. I disengaged the mower, and put the tractor in neutral. I gave it more throttle, and it helped a little, but it still was going to stall... When I choked the engine, that helped, and kept it from stalling, but it was still idling quite low. Sounded like it was going to die and/or out of gas, so I decided to turn it off.

Turned it off for a few minutes to check for debris on the cooling fins (clean) and gas level (still a third of a tank... the behavior was like when you run an engine out of gas). Let it rest about 2 minutes while I scratched my head. Started it back up, but still idling slow/threatening to stall unless I choked it. After a few tentative tries and a minute or two, it seemed it was not going to stall, and then I could put the choke back in, and it started to sound strong and normal. I mowed just a little more before heading it back for the shed (didn't want it to get stuck out in the impending rain, but it did fine for the last bit of mowing, which I did at a slower speed... no hint it was going to stall again.)

My only theory is that it got overheated with the weather and mowing for so long, and that it was getting vapor locked, so letting it idle and cool a bit helped. Just a layman's theory.

Does that make any sense? Anyone more experienced have any ideas?
[It seemed strange to me that choking the engine was the only thing that seemed to help it... and then after it rested, then idled a bit like that, it ran strong so I could put the choke back in (i.e. de-choked it) to run normally. ]

Thanks in advance! -Mitch

 

[Mean Jean]

Maybe it's time to replace the fuel filter.

 

[PatasColo]

I'm pretty sure this one doesn't have a fuel filter, but I'll double-check that! Thx for the idea.:thumbsup:
It had occurred to me too that something might've gone through with the gas and given the engine some momentary problems until it flushed out of the line.

I'm surprised I haven't gotten a few more responses, given all the VERY mechanically knowledgeable folks I know are on this site... I've seen them respond to questions like this in all kinds of other threads.... BUT maybe it's because I didn't put either "Kubota" or "Deere" in the thread! :ashamed: :laughing: :laughing: :laughing:

(Wish I had one of those... a co-worker just demoed a Kubota BX2620 over the weekend, and it sounds like he is going to buy it. Wah! )

 

[Mean Jean]

I just took a peek at the machine in question.
That's a mean set up!

Check for a fuel filter, clean the air filter, replace the spark plugs. (if it's a gas engine)

 

[oldnslo]

Does the Kohler engine have an ignition coil like a car or is it the newer electronic ignition. My old JD112 with the Kohler "K" series motor would do this when the coil was getting weak and it got hot. Mine would usually idle but would not develop any power or gain any RPM's.

Your thoughts on vapor could also be valid.

Roy

 

[JRobyn]

That engine/carburetor has a big knurled/slotted carb main jet adjustment. You might try screwing it in until it just bottoms, counting the exact number of turns. Then take it all the way out. Do this while the engine is running (it will stall, but that's to be expected). Squirt a bit of carburetor cleaner down the jet hole, then replace the jet exactly the same as it was (lightly bottom it and then screw back out the same number of turns). If there is a bit of trash in the carb, this will often flush it out.

It also has a removable carb bowl that you can easily take off to drain any water or crap that has accumulated. If I remember correctly, it is a 3/8 (soft) brass nut on the bottom of the bowl. Shut off the fuel petcock at the tank, then clean around the edge of the bowl, then carefully remove it. There should be a thin rubber gasket/o-ring, so be careful not to damage or lose that. Pour out the bowl, turn on the fuel petcock for a moment to flush out any crud in the fuel line, then replace the bowl. Be careful to gently ease the bowl back over the float that will be dangling from the carb.

 

[T_e_r_r_y]

Could also add sea-foam to your gas and spare fuel cans.

Little bit goes a long way mix to specs. Lot of people avoid using gas with ethanol in

it, seems to slowly dissolve the rubber fuel lines, gaskets and plastic parts. As was said

before, pull off the bowl and see if there are minute pieces floating in the gas. Don't know

how old the unit is but, would also look in the gas tank for rusting or pieces flaking off the

sides.

T.J.

 

[PatasColo]

Thanks for all the feedback fellas. I'll be checking a few things once this rain lets up (we've been having storms every afternoon/evening here for days). It is an older setup, 1969 or 70, and has a ignition coil I believe, so there may be something to that.

I just got this Gravely this spring, and it's been a godsend. Really cut down our mowing time this year, and I paid less than $500 for it. I've been learning my way around it, doing one maintenance task on it each time I use it, so you all have given me a couple more. I was especially glad to get it for so little $$$ and that it's built like a tank, because we have a lot of rocks on our property. No matter how many I pick up, new ones always showing up. A lot of the foothills right around us are enormous sandstone slab quarries.

 

[oldnslo]

From 69 or 70 would probably be the "K" series engine. My 112 is a 73 so is a similar vintage.

What you can try and might help eliminate possible items is to have some tools available to check spark intensity cold Vs hot. Visual check for spark color and how large of a gap will it jump. Not real scientific but may provide some insight on whether the spark is getting weaker as the engine and coil heat up.

 

[PatasColo]

Followup:
Well, went to use the Gravely again to mow my 3/4 acre field. After about an hour, I noticed some smoking, and fluid dripping off the bottom left side. At first, I thought it was hot oil. After a bit more looking, I could see the little fuel pump sputtering out fluid in teensy droplets... must be gas, which was then mixing with the oil/dirt caked underneath the fuel pump area, and dripping down off the bottom of the tractor (mixture of gas and oil by the time it dripped).

Fortunately, I was about done for the day... I don't like smoking gas running on the outside of any machine! So I ran it back up to the shed and turned it off. Called around today and found they don't sell the pump rebuild kits any more, but Richard's has a replacement pump (now plastic body I believe, not metal) for about $50. I ordered that.

With the pump going bad, I'm sure this was related to the problem I explained in starting out this thread. Glad that the fix is not so expensive!