My Engine Won't Start
One rule of thumb I always try to follow is to replace the cheapest
Here are the best things to check if the engine won't start:
Fuel level: Fill gas
tank to just below the fill neck so there is room for the gas to expand. If you fill the tank all the way to the top, then gas will leak
out as the engine moves around. Also should also check for a dirty or clogged fuel filter and
make sure the fuel valve is in the "ON" position.
2. Prime or Choke the engine: If the engine
has a primer or choke, use them. Prime the engine 3 times and then attempt to start
engine until it starts to fire and then open the choke. If this does not work, then use the below instructions.
3. It's possible the Carburetor is clogged: NOTE: You may want to
check the engine for spark before messing with the carburetor. To unclog a
carburetor, remove the air
filter and spray carburetor cleaner or starting fluid into the air intake and
crank the engine. If engine fires and then quits, stop the fuel flow,
remove the bowl nut and bowl. Blow compressed air or a run tag wire through the
holes in the bowl nut and clean the bowl of any debris. (A tag wire is usually
the best way to handle this) If there is a lot of debris in
the bowl, dispose properly of the old gasoline and flush the gas tank, fuel
line, and replace fuel filter (if your engine has one). If the high speed is adjustable,
remove the adjusting needle from the nut and run a wire through the holes.
**Tecumseh engines with an adjustable high speed have a third pinhole under the
top set of threads. Make sure this hole is clean. Use a tag wire will to clean the
hole. Make sure you can see the wire through the nut when looking into it. Also,
the tag wire up the nozzle in the carburetor.
On large 1 and 2 piece Briggs
and Stratton Flo-Jets, make sure you remove the high speed nozzle out of the
carburetor. NOTE: **You must have a 1/4" screw driver that DOES NOT have the
bulges on the side. Using a regular screw driver will damage the threads.** Blow
air through all the holes and make sure you can see light through all of them.
Reinstall the nozzle until tight. Reinstall the the bowl and then nut. Screw the
adjustment screw in until it is finger tight and then back it out 1 1/2 turn to
get the pre adjustment.
4. The Engine has been over choked: Open choke
and crank engine with the throttle at wide open until the engine starts.
5. Check the spark plug: Make sure you
have a good connection. If it is really black it may be "carbon
shorted", (i.e. Have carbon between the electrode gap). Clean or replace it. If the plug is
pitted, burned, or has cracked porcelain, replace it with an identical
replacement spark plug. Spark plugs are cheap and you should keep an extra in
your garage in case of failure.
6. Check for spark: Using a commercially
available spark tester, test for spark by putting the spark plug wire
(high-tension lead) on one side of the tester and then clip the other side of the
tester to the shroud, fins or head bolts. (i.e. Ground it) You can also ground the plug, with high tension
lead on it, to the head of the engine and crank on the engine. NOTE: **Keep the
spark plug away from the spark plug hole so spark does not jump and ignite any
fuel vapors.** If a spark is present you will see blue sparks jump the electrode gap.
If the mower is older than 1983, the points could be burned. Or the solid state (electronic
ignition) magneto could be bad.
7. Safety devices (Also known as Compliance Positive Stop) are disengaged: Put the
equipment in Neutral or Park, disengage the deck attachment or PTO and depress
the clutch. Some lawn tractors require you to sit on the seat when starting the
engine. If all the safety devices are engaged and the equipment still will not
start, there might be a problem in the wiring or the switches or modules have gone
8. Ground (stop) wire is grounded: Sometimes the the stop wire will rub against the flywheel
and cause it to be grounded. You will need to remove
the air shroud to check it. If the wire is touching the flywheel, repair the wire and
reroute it so it can't happen again.
9. Remote fuel pump is not pumping fuel: This problem occurs when the
diaphragms get hard in the fuel pump. Remove the fuel pump from the engine
shroud or off of the tractor itself and take the fuel pump apart on a work
bench. Always use Model and Type numbers off of the engine to allocate the
correct parts for the repair. If the fuel pump is mounted on the tractor, not the engine, then
you will have to get the Model number off of the TRACTOR to get the diaphragm
part number. Of course, you can also replace the entire fuel pump.
problem is low or no vacuum at the pulse line. To test for pulse, remove
pulse line from the fuel pump and put your finger over it. Crank on the
engine. If you feel your finger being sucked on, then you have
sufficient vacuum to operate pump. If you have no or little vacuum, then
check for a cracked or broken hose and replace it if you find a problem.
10. Problem with safety switch: Either the
safety switch is broken or the wires going to it are loose, or have some sort of
corrosion on it. Check for good connections.
11. Problem with zone start cable: If you
have a push mower, it is possible that the zone start cable (cable connected to
the bail you pull back to start the engine) is not pulling the flywheel brake
back all the way, thus causing the switch to not break contact. To remedy this,
either tie a knot in the metal wire to shorten it or, if possible, drill a hole
just a little lower than the current mounting hole and mount the cable to that
12. Fuel Cap: It's possible the fuel cap is not venting. A
non venting fuel cap will cause a vacuum in the tank, preventing the flow of
fuel to the carburetor. If the fuel cap is not venting replace the cap.
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