Time for New Carb ?

[GTSRider]

Ok.... now into my 3rd month of trying to track down a bad, weird problem.
Engine must run at 1/3 rd choke...or it runs lean...or appears to anyways.
I have had other problems with running , and have replaced with new parts....
PTO switch
PTO vacuum switch
Ignition switch
found bad connector in PTO switch harness, which was preventing starter
from engaging
But now I still have strange lean condition.... AND I MUST engage
PTO at low rpm or engine will die under load.
Will also want to die under any quick load given to it....ie....
stepping on forward pedal too quickly... hits thick grass suddenly.
Have cleaned carb more times than I can count... and every orfice is clear
but the "capped" idle jet.
Thanks for your input.
Pete

 

[GTSRider]

Oops ....forgot to add new carb fuel cut off solenoid , and new brake switch was also installed.

 

[Alien]

I would be ripping the cap off and removing the idle jetscrew and give it a good high pressure blow through before I looked for any other problem. I have had two small engines in the last week doing the same and each had varnish/deposit in the bleed hole.
Now they run like sewing machines.....:thumbsup:

 

[bp fick]

I fix/repair a lot of small engines for folks around here. The little plastic carbs for under 7 hp Briggs type? If I can find a carb for less than $35 off the internet, I just have one shipped. If it is a larger displacement engine, my budget is around $95.

The owner wants the machine running ASAP. Typical.
I want to be in and out of the job ASAP.

I'll only allot so much time for tinkering-cleaning and rebuilding. I don't have time to spend fussing with these things very long. Sometimes a little cleaning and they're good to go, but in far too many cases, the long term effects of ethanol blended fuel and plastics and cheap designs makes for a bad situation.

Long way to say that if you just order a new carb, at some point, well, do what you gotta do. I've gotten a bit more jaded about this stuff.

 

[oldnslo]

A couple of questions:
How old is this mower?
have you ever performed a compression check?
Have you checked valve clearance?
Does it get worse as the engine gets warm?

If the mower has some age / hours the valve could be wearing into the seats which will cause loss of vacuum to draw the fuel mixture into the carb.

Like BP said. Wonderful blend of ethanol and garbage gas don't take long to turn plastic and rubber into junk.

Roy

 

[GTSRider]

To BP fick.... I have thought of a new carb ...expensive Keihin one barrel....
similar to an old auto carb.
To oldnslo... 2003 Cub Cadet 3000 series
No...I have not performed compression check
No.... I have not checked valve clearence
The odd thing is cold or warm does not seem to matter....must be run with 1/3rd choke from cold start, and when hot.... which it runs very hot by the way.
You may have hit on valves... never thought of that ...thought they were hydraulic.
Thanks ...
Pete

 

[Soundguy]

needs choke to run:

vacume leak ( leans mix.. choke enriches mix.. etc.. ) could be manifold or intake gaskets or carb to manifold gaskets.

weak spark ( rich mix fires easier than a lean mix )

fuel obstruction ( anything from a plugged tank vent to a plugges scree, or dirty fuel system / carb.

soundguy

 

[GTSRider]

Soundguy.... thanks... I was thinking of spraying carb cleaner around carb
while running to check for leaks.
On fuel obstruction... I have replaced every line and 2 brand new filters...
although... it could be crap in tank.... really don 't want to pull tank.
Strange... all this after 100 flawless hr's of mowing last season.

 

[Soundguy]

check flow from tank.

soundguy

 

[oldnslo]

Running HOT is also an indication of running lean.

When using carb cleaner have a fire extinguisher handy. One spark and you have a flame thrower in your hand. Would also advise trying this outside and not in your garage.

Roy