Lawn Mower Carburetor Cleaning
Lawn Mower Starts Then Dies
Remove plug wire and turn off fuel as before. Loosen bolt on the fuel bowl. Remove the air filter, clean or replace before refitting.
Loosen the air filter housing, two or three bolts usually. Have a suitable container for small parts.
Pay attention to the gaskets and their locations. The gaskets are the paper type material sandwiched between the carburettor and engine. These gaskets must go in the correct location and orientation.
Don't be intimidated by all the pipes and levers. It is straight forward. Take your time, lots of pictures and you'll be fine.
A typical carburettor will have a fuel line, breather pipe, throttle lever and spring. May have a choke lever, depending on choke system.
It'll look like this, dirty, if you have compressed air, blowing off the grime makes seeing components easier.
Remove the gas line - use a screwdriver to prise it off.
Remove the crankcase breather pipe.
Remove the air filter housing bolts, and housing.
Holding the carburettor in one hand, turn it sideways to release the throttle link, spring and choke lever.
Move to a clean area, remove bowl.
Remove the float and needle, this is done by pulling the pin.
The needle will have a rubber tip seal or the seal will be in the seat of the carburettor.
A worn seal turns pink. When seals wear they can cause too much fuel flow or no flow.
Remove the main jet with a flat screwdriver, these jets are made from brass which is a soft metal and will damage easily. Be sure the screwdriver is a good fit.
The dirt collects in the jet because it has small port holes which gas flows through.
Make sure all these ports are clean. Use a strand of wire to push through the holes.
Use carburettor cleaner to clean all the passage ways and port holes.
Spray through the fuel inlet pipe, throttle plate, choke plate, float and needle.
Drain the gas tank completely and change the fuel filter (if fitted). Some mowers have the filter in side the fuel line at the tank or in the tank.
Refit carburettor in reverse order.
This bit gets overlooked, but it's important. Clean out the fuel can. Check it for grit and if you're not sure the gas is good, replace it.
Fill mower with gas and turn on fuel.
Your ready to mow, Nice work!
Gas Flow Test
A fuel tank needs to breath. When fuel leaves the tank it needs to be replaced with air.
A sealed tank will prevent fuel from flowing.
To test cap, remove fuel bowl and then remove cap, if fuel flows now then gas cap is faulty.
Check the gas tank, look inside for debris blocking the outlet hole.
If you can't see in, remove the out let pipe and check flow, it should by a constant steady flow.
Dirt in the tank is very common and it will slow or block gas flow. Sometimes it may be necessary to remove the tank to clean.
Check flow on lines.
Check walls for cracking and leaks.
Check the fuel filter, common types are:
Bottle type are easy to check as most are see through. They can't be cleaned.
In line filters are fitted inside the fuel line at the fuel tank. They can be cleaned and reused.
Tank filters are a mesh screen in the bottom of the fuel tank. They can be cleaned and reused.
To test remove the fuel line at the carburettor, no flow suggests a filter/gas tank block.
Remove the float by sliding the pin out. Check the needle seal.
The needle tip seal turns pink when worn, some carburettors will have the seal in the carburettor needle seat instead.
Use fine wire to clean out the needle seat in the carburettor.
Blow some WD carb cleaner into the needle seat on the carburettor.
Fuel should start to flow, if it doesn't, remove and clean carburettor or replace with a new unit.