Any small engine/lawn tractor mechanics out here?

TAHOE · **Posted:** Thu May 13, 2010 8:21 am

Ok, so my dad has two tractors, Yard Machine & Craftsman, both have same B&S 18 hp Twin Cyl I/C motors using a vacuum actuated fuel pump type carb mounted on front. They both will start, but as you push the choke off, they begin rpm surging up and down, the choke has to remain half to full closed to keep them running. I looked down inside carb and when the surge starts the "bogging down" effect, it appears gas is pouring out of the center nozzle inside carb, then the flow slows and rpms increase, then bogs again, etc. I removed both carbs
(removed jets) and sprayed them with cleaner, but no help.
So I'm thinking I need to get a completed rebuild kit and tear them down completely????
Can a bad gasket inside the fuel pump cause this issue?
I would love to find out why it's doing it then I can fix them, sucks both of them doing exact same thing, now I got to haul my tractor over to cut his grass :banghead:

Thanks for any info!!!!

Cherrie 274 · **Posted:** Thu May 13, 2010 12:44 pm

See if this helps.The jets should have a tiny hole in them.This gets plugged, try using a small needle to unplug.Also make sure the float does float!

VoodooMann · **Posted:** Thu May 13, 2010 1:52 pm

try the following:

Fuel filter,

Air filter,

Spark plug (obviously)

Change oil

If still no avail.

start and run, remove air filter, spray carb and choke cleaner into the intake while running (small squirts) this usually works for me.

I work at sears and have to fix peoples $#!% all the time, :lol:

JeepinJarhead03 · **Posted:** Thu May 13, 2010 2:36 pm

Voodoo! i Bet you do have to fix peoples doo doo all the time

Those new Automatic Throttle lawnmowers are pieces of CRAP, i threw the last one we had in a tree

stupid spring loaded junk

RedKJ04 · **Posted:** Thu May 13, 2010 4:13 pm

I am still thinking the problem is in the carb. Try rebuilding it provided the kit is cheap. If it isn't I would pull the carburator off and take it apart and try to blow every port out and then soak it in some cleaner for some time and then re-assemble the part and hope it solved your problem. I had the same problem with out Toro rider and this did the trick. Hope this helps, and you get the problem solved!

KJ 119 · **Posted:** Thu May 13, 2010 5:35 pm

This is definitely a carb problem.
Was this the same fuel from last season?If so ,was a stabilizer used?
If so and no stabil,discard fuel.Old fuel will gum up carb good.
Carb should be removed and cleaned good and then cleared out with compressed air.Should hear a slight pop when clear.
Did you mess with any of the settings?Hopefully not.

VoodooMann · **Posted:** Thu May 13, 2010 7:50 pm

If the gas is more than 30 days old I'd put it in the 'Hoe, nowadays standing life for gasoline is less than 30 days.

ethanol loves water, new gas has tons of ethanol. new gas very rapidly becomes nasty water :lol:

TAHOE · **Posted:** Thu May 13, 2010 8:45 pm

the one tractor has sat for a few years with noting other than starting once/twice a year. The other has had a tank or two of fresher gas ran through it already, I've cut grass several times. I need to change the fuel filter on both and I guess drain both tanks.
I did change settings on the one carb when I remove needle to clean it out, but screw back in, then back out 1 1/2 turns and fired right back up. The other one has no setttings, just a orafice type setting that can't be adjusted. I partial took oboth aprt and cleaned out with carb cleaner and blew out, guess maybe something in the bowl still. I'll check on rebuild kit/filter, then get back with ya all.
At least I got a new blade on my tractor, I can tote it over and cut dad's grass with it.
VooDoo.... put old gas in the Hoe??? Perish the thought, now maybe the Libby though!!! :jester:

BugginKJ · **Joined:** Mon Jul 06, 2009 7:35 pm **Posts:** 4576

Just had the same issue with mine, turned out to be an air leak at the bunge hole cover near the throttle and choke rods. Small little metal caps that are pressed in and replace able, I gave them a good coating of rtv and it cured the problem. Might check to see if thats your problem.

TAHOE · **Posted:** Thu Jun 03, 2010 10:16 pm

UPDATE: removed, tore carb apart, cleaned, and rebuilt carb with all new parts, drained gas tank, added new gas. It fired right up and ran decent on top end. Now I have a problem that it will not idle all the was down, can't figure out why. I have the low idle screw backed out, but it's like the governor will not let it idle all the way down. It is acting like an older carburated car would with a vacuum leak. I'm scratching my head now, not sure what changed. Also seems to have a miss at all rpms, going to buy two new plugs and see if that cures the miss issue.... UGH :dizzy:

Any small engine/lawn tractor mechanics out here?

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