Carb adjustments

[FishhuntLA]

OK,

I know this is mainly a chainsaw forum, but many of you guys know small engines.

So I have a mower with a Brigss and Straton that seems to be missing and then when I engage the blade it bogs down and quits under load.

So I am going to pull the plug to see if it is fowled and running rich maybe.

Any ideas, Do I turn the adjustment screw in all the way, or back it out to get started???

Thanks guys.

Erik

 

[Al Smith]

Well ,if it has a tank that's got a tank hanging below it,it has,believe it or not,a type of diaphagm carb.The diaphragm part is the fuel pump.More than likely the danged thing has a stiff diaphragm[I hate that when it happens ]There is also a ball check on the end of the tube that goes into the tank,that could have some crude built up in it.If it has a Briggs engine,they have an excellent website,with trouble shooting guides.Best of luck,as mowers can be a big of a pain in neck as chainsaws.

 

[2Coilinveins]

Does the mower start ok? If it starts and runs fine for a bit, then starts acting funny, check and make sure the fuel tank is vented properly. Starting easily also points away from a bad plug. If it has a float carb, you might pull the float bowl and see if it's full of water or sediment. Sometimes the float will spring a leak (metal floats) or become fuel logged (plastic floats) and become sinks, flooding the engine. As to the adjustment, I start ~2.5 turns out from seated, that'll get it to fire enough to tune from there. Does it smoke any? Black means rich, white means lean, although it'll probably die before it runs that lean. HTH.

 

[Big feller]

In my experience the adjustments rarely go out on the Briggs engines. It is more than likely that the diaphragm is getting tired.

Several of the B & S mower engines have a tank within the top of the gas tank, just under the carb. The vacu-jet models keep this small tank filled to supply the carb with an even diet of fuel and prevent the changes in running that you would normally get as the tank runs lower.

There is a sort of a flap valve in the diaphragm that has to be in good order to pump the fuel into the upper tank. If the mower is more than ten years old it would benefit from a new one.

Just one word of warning - some of these carbs have a spring and cup arrangement next to the diaphragm - take it apart SLOWLY and note where everything goes. It isn't all that obvious which side it goes.

DC

 

[NWCS]

i would rebuild the carb, a briggs motor is EASY to work on! base carb adjustment stated in my factory service manual: needle valve: 1 1/2 turn out.
idle valve: 1 1/4 turn out. from all the way screwed in lightly.

 

[JohnL]

If it'a newer engine, it may not have the high speed mixture adjustment. You probably have checked the air filter, they can get pretty plugged up if not serviced (foam element) or replaced (paper element). If it does have the high sped mix screw: If it runs, the carb adj is close, set it at full RPM, find where it slows from being lean, then go the other way till it gets too rich, set it about midway then maybe go a tad rich for power while under load. You can download alot of the owners manuals from Briggs for the model type and code number.

 

[FishhuntLA]

It does belch some black smoke and then backfire some just before it decides to die.

It starts very easy second or third pull. but then just really chokes along and coughts, spits black every once in a while, backfires etc.

I got it sort of babied along and then it sort of kicked in like it was running better.

Carb unit is above the fuel tank, and appears to ahve another small tank, so I will look for crud in there. I saw some crud in the fuel tank, so think that old fuel being run out, clean it out, and lookinto the carb items and see from there.

Thanks for the settings on the screws. Will adjsut adn try.

Thanks guys, more to follow.

Hey new saw on the way!!! Yeah looking forward to cutting some wood with that puppy.

Erik

 

[Stumper]

Sounds to me like you may have sheared the flywheel key. Sometimes they wind up in an alignment thta will start and halfway run but not actually do any work.

 

[FishhuntLA]

How would I check for that??? Flywheel alingment Key that is???


Erik

 

[scottr]

engine

Erik , usually a partially sheared timing key will cause hard starting problems . If you will clean the gas tank , air filter , and spark plug then we can go from there . Is this a B&S Classic engine ?

 

[klickitatsacket]

Stumper - good call. Running until it's under loads; sounds like the flywheel has some play in it.

 

[FishhuntLA]

Good thing you guys know what's going on, becuase small engine adjustment and repairs are not my thing. I can design and build one heck of a soccer field after you guys take out all the timber, but could not fix my saw or mower if it spits back at me.

Must continue to learn, but asking questions and trying to fix. I will clean up thursday and see where we are from there. After I play with my new toy!!!!!!

More to follow.

Erik

 

[FishhuntLA]

OK all,

I have cleaned out carb, plugs, airfilter, and put it all back together. It will not run with air filter on, it still is running rich, and not sure what to look at next, it appears to be getting way too much fuel into the carb and flooding out. It backfires, black sooty exaust, which tells me it is running to rich.

Also when I can finally get it started, it dies as soon as I try to engage the blade??

Help!!!

 

[Lawn Masters]

Could have a seized spindle on the deck, that would cause the engine to quit.

 

[FishhuntLA]

Well it is funny,

it does run but not well, and just seems to die out. But the running very rich and only without the airfilter tells me something is wrong in carb, or float or diaphram.

But I can check spindle deck thing.

Erik

 

[Fish]

Post all of the model,type, code numbers off of the engine, usually stamped above
the spark plug. From a glance at the discussion, it sounds like an old mower, like
pre-1983, so I would suggest the trouble is points. But not knowing what you have,
what type carb, ignition, etc. it is hard to say.

 

[FishhuntLA]

Thanks will go do that and post.

I just got back from Bowling Green Ky, How close to you is that??

Points, did not think of that, will get info.

Erik

 

[FishhuntLA]

Briggs and Straton on a Troy Built Mower

Motor model # 130902 Type #1233 02 Code #89041807

I will look up on internet and see what I can find out about points etc.

Thanks guys, keep it coming,

Erik

 

[Fish]

Bowling green is 1 1/2 hours away, and no you have no points to worry about.
You need to isolate the kill wire from the ignition, to see if that may be grounding
out, giving you these symptoms. It should connect at a terminal below the carb tank.
If you remove this wire, and the engine runs ok, then your problem lies in the safety
features of your mower.

 

[FishhuntLA]

Will look for that and detach, to see if mower runs.

More to follow.

Erik