Carb question on my riding mower

[SAWYER]

I have a Craftsman riding mower and yesterday it stopped running. It is getting fire and the plug is working so I took the carb off a when I spray starting fluid in the intake it fires right up. On the bottom of the bowl of my carb is a little square piece with a pointed end that screws in the bottom and at the bottom of that piece two wires in a plug hooks up to it. What is this for? My cleaned out the carb and it still wont start

 

[SpatiallyAware]

Sounds like the float and needle. Basically as fuel fills up in the bottom, the float lifts up and pushes on the needle which closes the orifice.


I used to spend so much time rebuilding those things as a kid.. Hours and hours on the weekends taking them apart, putting in the little rebuild kits, messing with float levels and washers under the needles, etc etc..

Back then the only option was a rebuild kit, but nowadays I just buy a whole new carb. My old snapper rider carb was like $30 from a small lawnmower shop..

 

[SAWYER]

What are the two wires for?

 

[SpatiallyAware]

I had an ATV a long time ago that had an electric fuel cutoff via two wires in the carb, that would be my guess.

 

[SAWYER]

So that might be bad, thanks

 

[twinrider1]

Yep, fuel cutoff solenoid to prevent an afterfire. Turn the key on and probe it for 12v.

http://www.youtube.com/watch?v=Kr6UayxyVwU

 

[SpatiallyAware]

It's a safety thing.. The key generally just cuts spark, so the mower/atv/whatever will continue to run until the carb is empty. I guess it's a fail safe in case power isn't cut... I'm not 100% sure on this though, just going off of 10+ years old memory here.

Are you 100% sure you got everything removed and back together correctly? Every single tiny washer has to be reinstalled just right. You have to remove every jet (brass with a slot to remove with a regular screwdriver) so the gunk can flow out. Just removing the bowl and spraying things out with carb cleaner can do more harm than good, as gunk is knocked loose behind jets and can't get out.

 

[SAWYER]

I just removed the trash from the bowl and sprayed the carb with carb cleaner.

 

[SpatiallyAware]

It sort of sounds like a stuck float needle to me. You can remove the float, and under the 'arm' there's a needle that slides out (unless it's stuck up in there)

Like I said though, you can push gunk up into the carb and make it even worse unless you remove the jets.

You might try putting it in a bucket and keeping the entire carb damp with cleaner. Spray it every 5-10 minutes for a few hours (or buy a gallon of carb cleaner and soak it)

Stupid question but are you sure it has gas? The last two times I helped someone with a problem like this the mower just didn't have enough gas in the tank.. it looked like there was enough, but added 1/2 gallon and it fired right up. Basically, it's pretty odd for a carb to fail while it's running like that.. If it had been sitting awhile then yeah, gunked up carb, but unless you have no fuel filter this rarely happens.

 

[twinrider1]

....so the mower/atv/whatever will continue to run until the carb is empty. I guess it's a fail safe in case power isn't cut... I'm not 100% sure on this though...

With no spark to ignite the fuel, the raw fuel can pass through the combustion chamber and to the hot exhaust.....boom, afterfire.

 

[SpatiallyAware]

With no spark to ignite the fuel, the raw fuel can pass through the combustion chamber and to the hot exhaust.....boom, afterfire.

Ahh... gotcha.. I've seen this happen but never connected the dots between that and the shutoff in the carb. Why do some people disable this?

 

[SAWYER]

Gas pours out of the bottom of the bowl when I take it off

 

[Ketchup]

I just had my carb rebuilt a couple weeks ago. The guy said the E-10 gas is really bad for those, so I have started going to the stations that have ethanol-free gasoline.

 

[SpatiallyAware]

Gas pours out of the bottom of the bowl when I take it off

Then the needle is ok. Does the flow stop if you lift up the float?

From what you described it sounds like fuel should be getting to the motor, it might not run perfect but it should at least start.

 

[SpatiallyAware]

I just had my carb rebuilt a couple weeks ago. The guy said the E-10 gas is really bad for those, so I have started going to the stations that have ethanol-free gasoline.

It's particularly bad when stored in small quantities. 10 gallons in your car will last 3-4 months easily. 1/2 gallon in a lawnmower will go bad in a few weeks.

I've had good luck with the additives that are specifically for making ethanolated fuel last longer.

 

[twinrider1]

Sears has a great parts site. Plug in your model number and check out your parts diagram.
What's your model number?

 

[Zenmervolt]

It's particularly bad when stored in small quantities. 10 gallons in your car will last 3-4 months easily. 1/2 gallon in a lawnmower will go bad in a few weeks.

I've had good luck with the additives that are specifically for making ethanolated fuel last longer.

I hear this all the time but I cannot say that I've ever experienced it. I shut off the valve and drain the carb in my lawn mower every fall but that's it. And 8 months later in the spring the engine fires up and runs perfectly on the 8 month old gas in the tank. The weed eater ran fine on 18 month old premix too.

If the gas is several years old then sure, there will be problems. But regular gas should be fine for a year without additives as long as it's in a sealed container.

ZV

 

[SpatiallyAware]

I hear this all the time but I cannot say that I've ever experienced it. I shut off the valve and drain the carb in my lawn mower every fall but that's it. And 8 months later in the spring the engine fires up and runs perfectly on the 8 month old gas in the tank. The weed eater ran fine on 18 month old premix too.

If the gas is several years old then sure, there will be problems. But regular gas should be fine for a year without additives as long as it's in a sealed container.

ZV

I dunno, in my bikes e85 was good for 3 months max and that's on a FI engine. My weedeater acts up after about a month, mowers are good for maybe two.

With the weedeaters/mowers they generally would refuse to start. I would drain the tank and then drip carb cleaner down the fuel lines, then screw with tapping carbs etc and they'd start up for me.

The bikes would have a hard time starting and run like crap until I filled the tank with decent gas.

I had an intruder 800 (fuel pump but carb'd) and I swear it would act up after a month of sitting. I don't know if the carbs had smaller passages or what, but it was very picky about old e85.

Once I started using the additives all of the problems went away.

 

[Zenmervolt]

I dunno, in my bikes e85 was good for 3 months max and that's on a FI engine. My weedeater acts up after about a month, mowers are good for maybe two.

With the weedeaters/mowers they generally would refuse to start. I would drain the tank and then drip carb cleaner down the fuel lines, then screw with tapping carbs etc and they'd start up for me.

The bikes would have a hard time starting and run like crap until I filled the tank with decent gas.

I had an intruder 800 (fuel pump but carb'd) and I swear it would act up after a month of sitting. I don't know if the carbs had smaller passages or what, but it was very picky about old e85.

Once I started using the additives all of the problems went away.

Wait, you're using e85? Most small engines are only set up to run e10 or e15, which is the stuff you get from normal pumps. The e85 stuff only works in flex-fuel vehicles; it's 85% ethanol. Or did you mean e15 (15% ethanol, 85% gasoline)?

Out here all we have is e10 (10% ethanol, 90% gasoline), and I've not had any problems with it keeping for up to a year. The "sealed container" bit is important though. If the container is vented to atmosphere it's easy for water to get into the gas through humidity in the air.

ZV

 

[SpatiallyAware]

Wait, you're using e85? Most small engines are only set up to run e10 or e15, which is the stuff you get from normal pumps. The e85 stuff only works in flex-fuel vehicles; it's 85% ethanol. Or did you mean e15 (15% ethanol, 85% gasoline)?

Out here all we have is e10 (10% ethanol, 90% gasoline), and I've not had any problems with it keeping for up to a year. The "sealed container" bit is important though. If the container is vented to atmosphere it's easy for water to get into the gas through humidity in the air.

ZV

Eeek I meant e10... 10% ethanol.

Maybe it's the venting, I have no idea. My small engine mechanic claims that 90% of his business nowadays is dealing with clogged carbs due to the ethanol fuel...

 

[Ketchup]

Eeek I meant e10... 10% ethanol.

Maybe it's the venting, I have no idea. My small engine mechanic claims that 90% of his business nowadays is dealing with clogged carbs due to the ethanol fuel...

Mine said the same. It didn't cost me much ($30 I think) to get it rebuilt, so I really can't complain. And it sure beats letting the grass grow like crazy until I would find time to (possibly) fix it myself.

 

[skyking]

I use Sta-bil in the last gas can of the year. Works for me.

 

[Zenmervolt]

Eeek I meant e10... 10% ethanol.

Maybe it's the venting, I have no idea. My small engine mechanic claims that 90% of his business nowadays is dealing with clogged carbs due to the ethanol fuel...

It's amazing how much variance there can be from one small engine to the next. Carbs from one manufacturer might be fine while other manufacturers don't tolerate things well at all. Small engines have always had finicky carbs though.

I'm inclined to think that most of the problems in small engines are around EPA emissions regulations rather than e10 though. As emissions have tightened, carbs for small engines have gotten more complex, with multiple jets and more closely controlled fueling, which means that it's much easier to gum up these newer carbs. Older engines basically just dumped "approximately enough" fuel into the intake (tending to err on the side of running rich) because no-one cared about the emissions from a push mower.

The reason that I think this is that e10 has been in use in parts of the US for a lot longer than people have been complaining about these issues. I remember seeing ethanol labels on pumps in Ohio somewhere around 2000 or 2001 but no-one started having "problems" with the fuel until the last few years, which are, coincidentally, the same time that the EPA started phasing in new emissions requirements for small engines. (This is also why things like scooters and small outboards have gone to 4-stroke rather than 2-stroke engines.)

That's my thought on it anyway. I could be completely full of shit. Wouldn't be the first time.

ZV

 

[SAWYER]

I cleaned it but as simple as it seems, I am having trouble hooking up the linkages for the throttle and choke. It runs now though

 

[SpatiallyAware]

I cleaned it but as simple as it seems, I am having trouble hooking up the linkages for the throttle and choke. It runs now though

It sometimes helps to disconnect the cable from the control end, connect it at the motor, then reconnect at the control. Good job on getting it running! :thumbsup::thumbsup: