Small engine problems

[Charlie M]

All my small engines rototiller, high pressure washer and snow blower all developed problems after only about 3 years. They all need to have the choke partially on to run smooth. I know its a carb issue. In the old days there was an adjustment on the bottom of the carb bowl that would fix the problem. Since they don't have that adjustment any more what is the fix? Running carb cleaner doesn't seem to help. Is there one jet somewhere that is typically plugged up?
 

[rustyj14]

Ccheck the air breather hole in the gas cap. Must be open. That little hole has made lots of money for repairmen, over the years. RJ
 

[Jay Phillips]

More than likely the carb should be disassembled, spray carb cleaner through all orifices, replace gaskets and diaphragms if necessary...and assemble.

From this point forward, use only (stabilizer) treated fuel. If it's not going to be used for a while, siphon tank empty, start engine and let it run until it cuts off.

Next time you want to use it, add NEW treated fuel, and fire up.
 

[G1355]

Probebly getting gummed up of green stuff ours do the same thing, we've figured out it works best to buy a new carb for 20 bucks then cleaning them and having it happen a month later.
 

[John B.]

IF you have to run with the choke partially on that means there isn't enough fuel flow thru the carb. So yes you may have a plugged jet or a fuel restriction some where between the carb and tank.
 

[retired farmer]

Always used to have carb problems with Briggs and Stratton engines. Finally cured it. When you fuel them put about two or three tablespoons or so of Marvel Mystery Oil in each quart of gas. Yes, I know, there are people who don't believe in MMO. Yes, it does work.
 

[DCPULLER]

If there is a place where you can get non ethanol gas around you it will take care of the problem once your carb is cleaned.
 

[G1355]

Yeah go to a airport and get aviation fuel, never goes old and isn't corrosive, won't gum up jets or anything, we've been using that for awhile and works really good, about a dollar a gallon more than regular gas though.
 

[OldGas]

Av gas is fine, just don't store in a plastic container or tank, it will turn milkey if in the sun for any amount of time!
 

[kevinsstuff]

try a prouduct called seafoam use as directed. seafoam also makes a good penetrating spray.
i use premium gas in my small engines not because of higher octane bthut for cleaners added to the gas . my 2 cycle engines seem to like the premium gas
 

[G1355]

Well we've had it in everything from pump motors, motorcycle and garden tractors guess it hasn't turned Milkey yet and some sit outside in plastic tanks. When it does this then is the fuel junk and the motor won't run?
 

[rrobert]

Check gas for water. I would pour gas from container into a clear plastic pop bottle. Water will settle to the bottom after about 10 minutes.

Very odd for all three to have the same issue at the same time. Gas is the shared factor.

Water will ruin a sparkplug and clog the paper fuel filter(if aplicable).

The bad sparkplug will have spark but not to the electrode. It will spark around the ceramic insulator.
 

[oldhousehugger]

From Wikipedia I quote them on fuel air ratio by weight. “A stoichiometric mixture is the working point that modern engine management systems employing fuel injection attempt to achieve in light load cruise situations. For gasoline fuel, the stoichiometric air–fuel mixture is approximately 13:1”.

So for a 4 cycle engine to run the weight of air needs to be 13 to 14 times the weight of fuel to be burned.

If that fuel air ratio gets out of whack she don’t run so good.

Depending on MFGr and model if there is a gas tank attached to the carb as there are on many 1-7 hp engines there is a fuel pickup tube with a fine wire mesh screen at the bottom which sucks gas off the bottom of the tank. If debris of any kind (crud) clogs the screen, it will need extra vacuum which the choke provides in order to get gas thru the plugged screen and up the tube into the carburetor. Also as said here by someone else in this thread, the main and idle jets can get gunked up.
Often there are tiny openings in the ventury region of the carb which need to be cleaned out.
I use a very fine diabetic insulin needle to clean out these tiny openings. Your tip cleaning tool for oxyacetylene torch has a variety of slightly larger reamers for bigger jets. Remember that you only want to remove aluminum oxidation and varnish deposits, NOT metal. If you enlarge a jet even a little it will not meter fuel or air as designed and therefore the engine will not run well either even though everything looks clean!!!! In other words if you ream a jet oversize it will let to much fuel thru and the engine will always run to rich.
Another thing to look for is whether the mating surface between carb and engine block is leaking air. If so that alone will cause a lean condition to exist and in turn require more fuel to sucked into the engine so it will run. Get to big a air leak and the engine will starve for fuel even with the choke on. Another place air can leak in is around the throttle shaft. Thats easy to check just by trying to wiggle the throttle shaft. If it wiggles around in the casting you need to consider placing a leather or felt washer on top of it or getting the carb body rebushed.
Many newer small engines have one or more orings which are intended to provide an air tight seal between various components manifolds and the block. If an oring is out of position or damaged it doesn't do it's job.
On some carbs there are primer bulbs which are made out of a material which is affected by various gasoline additives. You will find that on higher end equipment the synthetic components will last for years even with the additives. A lot of cheaper engines use easily dissolved tubing and other rubber parts which don't last. If you get a hole in the primer bulb which leaks either fuel or air, there is another problem. Seems like maybe the engine manufacturers are in a p***ing contest with the fuel suppliers over who is to blame. I take the position that the engine is the end user and should be designed for the environment and FUEL which it will be subjected to. Go figure. I have a 20 year old Husqvarna 44 chainsaw with the original fuel lines still in it. It runs great. Gee how could that be? Good plastic tubing obviously. I have repaired 2 year old throw away saws that needed new fuel lines already.