Carburetor cleaning?

[dart451]

Sometime I have good luck, sometimes not! I'm working on a craftsman rototiller, Briggs 120302-0432-E1. Engine starts really easy but doesn't like to run smooth with choke fully open...smooths out choked a bit. So, I figure it's starving for fuel. I pulled the carb, took it apart and ran my ultrasonic cleaner, cleaned up nice, blew out all orifices. I also checked keyway, it was perfect, spark plug new, gapped properly. Put it back together and it still runs the same. Also, I removed fuel tank, cleaned out and put fresh fuel in the tank. So, do you guys get carbs that just don't clean up and you have to buy a new one? It seems I have about a 50/50 chance of the carb cleaning up correctly!?

[Luffydog]

U could say we all have a 50 to 50 chance at it. Did u clean the brass jet out that holds the float bowl on? I use touch tip cleaners to clean the holes out and run them up thur the carb. Then use brake part cleaner to spray thur the passages watching out not spraying in eyes. But after a couple of times trying I just bite the bullet and buy the new carb. After couple of times of your time trying then your in the hole. Check orings and gaskets to see if all good and sealed. Good luck

[dart451]

That's kinda what I thought but hadn't asked anyone about it before. And yes, I also use my torch wires to run through the orifices. The air filter base plate was damaged and you could see where all kinds of dirt could bypass the filter!

[rogerf]

Hi Dart,

I'd try another plug, one that's known to be good. Don't just trust a brand new plug.

I've been lead round in circles with symptoms of a weak mixture, cleaned three times and then replaced the carburettor with a brand-new manufacturer's original, still the same. Turned out to be that brand new properly gapped spark plug .

I'd never run into that before and thought I was going crazy, tried an old plug of the right type that I'd just changed on another machine and that 'bad carburettor' ran perfectly! Then another new plug (#3) and it worked fine and still does.

Cheers from Oz,
Roger

[bgsengine]

From long experience after several years of running stuff through ultrasonic cleaner and all the other tried and true methods:

if there are any jets or metering rods that cannot be removed/replaced with new service parts, and the Carb is a fixed jet (non-adjustable, not counting idle mixture) and water/rust/corrosion is found in carburetor or float bowl, (Especially true on pulsa-jet Briggs carbs) We don't even bother trying to clean them - they get a new carb. period. we see about a 90% failure to 10% success ratio trying to clean those carbs - and even the adjustable ones never really run right.

If it is just gum and varnish build up, we see a much better success rate (85%) but if they show corrosion or rust - they're D.O.A.

Applies to *ANY* emissions rated carburetor we see- float , pulsa-jet, cube carbs - whatever. Corrosion just isn't fixable. (and most cube carbs on saws/trimmers, we can tell just from a 2 minute pressure test of fuel system if it'll be fixable or not)

[KE4AVB]

Sometime I have good luck, sometimes not! I'm working on a craftsman rototiller, Briggs 120302-0432-E1. Engine starts really easy but doesn't like to run smooth with choke fully open...smooths out choked a bit. So, I figure it's starving for fuel.

I know I going to get chastise for saying this...but here goes anyway.

What you describing is a slight lean burn. Re-clean the main jet as these sometimes just don't get cleaned very well.

On this particular carburetor If the problem persists then you would need to resize the main jet to the next larger jet size but only to next size that stops the lean burn problem. Over-sizing beyond this will cause the engine to run too rich. The resizing will take those micro bits that are available out there.

[dart451]

Thanks guys! That give me some insight! I thought it was primarily me not doing a good job on cleaning carbs! Ke4avb does have an interesting fix!? Course, I do not have any mini drill bits for this purpose or I might try it cause that's what's happening! It is easier to throw on a new carb though...that's always worked for me so far. Time is money and customer pays for the carb anyway.

[bobodu]

50:50 is about right. Don't do any "paying work" these days so I am free to buy the cheap aftermarket ebay carbs. For $10 more or so than a kit...I'll get the carb and be done with it.

[Arkie]

Put a new carb on it and then if it still acts the same do some head scratching. (air leak or ????)

[Deere2me]

Thanks guys! That give me some insight! I thought it was primarily me not doing a good job on cleaning carbs! Ke4avb does have an interesting fix!? Course, I do not have any mini drill bits for this purpose or I might try it cause that's what's happening! It is easier to throw on a new carb though...that's always worked for me so far. Time is money and customer pays for the carb anyway.

Ya don't need em! Just run your torch tip cleaner thru it, you can use one that slips easily thru and just kinda CLEAN the jet out a bit. It doesn't have to be perfectly round. It ain't a race motor! Just don't OVERCLEAN it! It doesn't take much to IMPROVE THE FUEL FLOW! In your case, you have to clip the lead in portion of the tip cleaner off 'cause of the lack of depth at the jet.
I clean the main jet REALLY WELL on just about every carb I work on. You'd be amazed at how well they run after a GOOD JET CLEANIN'!
On your carb, you can also pop out the main nozzle for cleaning!
Another thing ya wanna check for is a worn throttle shaft/bore or missing foam seal.
On some carbs I replace the foam seal with a dense felt one that I rub some hi-temp grease in, helps seal 'em up.

Personally, I have no use for an ultrasonic unit. I just use wires, brushes and my trusty stainless welder's toothbrush, a little dooby pad and some carb spray. and bingo!