Small Engine Carburetor Rebuild or Replace?

Rebuilding works 98% of the time.

What to look for to determine if replacement is needed.

1. missing parts.
2. broken parts.

Running swill like Arco gas through it will certainly cause any soft parts to degrade and need replacement a lot sooner.

Jeff

Sorry, but my crystal ball is in the shop and therefore I can't devine what you have and what problem you're trying to solve.

I have five chain saws and fix about a dozen more for the local wood chucks. Also weed whackers and blowers. Most of the fuel related problems I see are not caused by a tar and varnish clogged carburetor. It's the [deleted expletive] filter on the end of the fuel line at the bottom of the tank that gets clogged. There are also plenty of carbon encrusted reed valves (old saws) and intake and exhaust outlets that get clogged. I give the carb a blast of carb cleaner to remove any varnish and gum, and then fix the other likely candidates, such as a clogged air filter, crud on the spark plug, magneto problems, dirty points, etc.

However, I have one Husqvarna 136 where the problem really was in the carburetor. The previous owner torqued down the needle valves causing the soft aluminum valve seat to deform. I could make it run, but it wouldn't stay adjusted as the difference between lean and flooded was about 1/8th of a turn. $50 for a new Walbro carb was a bit much, but a rebuild kit would not have helped. By the time I was done, I had put more into this old saw than it was worth.

If you must learn by destroying(tm), a rebuild kit costs about $15 and an hour of your time. Try rebuilding first. If that doesn't work, look again at the obvious other problems. Last, buy a new carb. If that doesn't work, buy a new saw.

Yep, on chain saws. However, I'm zero for 5 attempts on automobile carburetors. After 5 disasters, I gave up.

Assuming a chain saw or lawn mower:

1. Brass needle valve with a circular grove and a matching grove in the seat.
2. Clogged intake to the cylinder.
3. Clogged fuel line.
4. Clogged fuel filter.
5. Clogged air filter.
6. Debris in the carb after the air filter was punctured.
7. Wrong fuel or bad fuel/oil mix.
8. Far too much Sta-Bil in the fuel.
9. Water in everything.
10. Mangled throttle linkage.
11. Automagic choke stuck either open or closed.
12. Timing adjustment on magneto position.

and the winner that took me several days to find.

1. Permanently shorted cutoff switch.

You should see what's left of my Homelite EZ when my semi-brilliant neighbor used Coleman camp fuel (naphtha) and a 50:1 oil mix. Worked great until the piston froze in the cylinder. I'll fix it one of these days when I feel like relieving my frustrations by pounding out the piston with a 2x4 and a sledge hammer.

However, you're right. Some solvents, cleaners, and gas additives attack rubber parts. The same neighbor mentioned that the saw seemed to be leaking oil, which I confirmed. What he didn't tell me is that he put some kind of solvent in with the chain oil to "clean it" resulting in all the rubber seals turning to slimy goo.

Why in the hell would you think asking this question in an "electronics repair" news group would be the right thing to do?

That aside, if you cannot answer the question yourself you should take the entire motorized mechanism to a qualified small motor mechanic for advice.

On Sep 26, 5:38=A0pm, Jeffrey Angus wrote: > On 9/26/2010 7:13 PM, Jon Claude Killy wrote: >

So which gas is _not _ swill in your humble opinion? I only ask because I've been running Arco for 25 years.

G=B2

The problem is the oxygenation (and other additives). It seriously kills the soft rubber parts like the pickup tube to the filter element in chainsaws and other small 2-cycle engines. It's not quite as problematic in 4-cycle engines other than the rubber lines and primer bulbs if they have them

The other problem is usage. Unlike automobiles, most power tools sit idle for weeks at a time.

What I told people to use when working as a service tech at the Yamada Co. was either Exon, Mobile (now the same) or Chevron. And to spring for premium. You're engine runs better and stays cleaner inside.

Also, premix the CORRECT amount of Stabile(tm) in a 1-5 gallon fuel can. As others poited out, too much is worse than none.

And NEVER let your friends borrow a chainsaw. I saw it over and over, "But we only had one more cut when we ran out of gas so..." (We welded the piston into the engine.)

Jeff The other other one.

All gas is the same except for the additives... The additives are added when the tanker truck (semi) is loaded with fuel to deliver to the stations, then it bcomes 'branded'.

But that oxygenation stuff is mandatory in all gas in CA - where I've been running the Arco.

G=B2