Outdoor Power Equipment (Lawn Mowers, Snow Blowers, Chain Saws and more) Discussions

Model 42A707 1653-01
Hello all,  I can't get this thing to run off choke.

I replaced the fuel lines, fuel filter, fuel and spark plugs.  I checked compression at 120 psi in both cylinders.  Spark was checked with a plug at 0.060" gap to check power of spark and both cylinders sparked fine.  I re-gapped at 0.030.

I rebuilt the carb, blew out all passages with carb cleaner/compressed air.  I am on round 3 of tearing this down and blowing out each port.

While it is running while choked, dropplets of fuel are spraying out of the carb throat onto me and everything else in the area.  When I shut it down, I can see fuel puddled at the collector below the carb.  Plugs aren't wet.

Any suggestions?  Thanks

I think your valve timming is off. If you are seeing fuel spit out the carb a valve ( intake is staying open when it should not. Check and adjust your Valves. If that is fine then there is still something wrong with your carb, like a clogged jet, If you have to choke  it to get fuel through it something must be clogged. Choking only forces fuel through you jets.    

If you have to choke it, it is not getting enough fuel.. If you are getting 120 psi compression it mostly like Han no problems with its valves. The engine has a nozzle under the main jet, the nozzle infuses air into the main jets fuel to "mist fuel" out . The nozzel if plugged will gurgle raw fuel instead of mist. This gurgled fuel will burn leaner than the misted fuel due to the fact it will not vaporize properly before it is ingested into the cyclinder. Clean the air passages in the nozzel, let us know what happens! Good luck, Friiy

Thanks for the replies.

I pulled the carb again and swabbed each port/nozzle with an appropriate sized copper wire.  No change...  It will just idle, while I jog the choke from 80-100% closed.   I'm at a loss.

I think that you have a problem with the fuel shutoff solenoid it may be bad or not getting enough voltage. Try running a jumper wire from the battery to the solenoid. If that works you have bad wiring or a bad ignition switch. Could also be water in the gas.

That's an interesting point. I assume the carb bowl is full, but do you have a fuel filter installed? Is it free-flowing? Bad fuel lines? If the carb bowl has a drain, will gas continue to come out of that, when you push the drain button (to check flow to the bowl)? Is the carb bowl float height correct?

I think I've heard people say you should hear/feel a click from the fuel shutoff solenoid when you turn the ignition on. I believe I've seen mention of tapping an iffy fuel solenoid to help perhaps loosen it up again. Does this have a fuel pump, or is it gravity-fed?

Is the carb adjustable? If so, I'm sure you've tried richening the mixture? The fact that fuel sprays out with the choke on sounds a bit odd. My snowblowers don't do that with choke applied (other engines I have that I recall running with no air filter installed). Everything is hooked up properly, I'm assuming. No throttle/governor linkage connection issues, or anything like that? If you spray carb cleaner (or similar) around (but not into) the carb, especially where it bolts to the engine/manifold, while it's running, do you hear a change? Is it possible you have an air leak somewhere that's making you run lean?

Does this have a fuel pump on the side of the carb with diaphrams?....If So the spring and cup could be on the wron side of the diaphram, or the hole pump could be put to geather out of order somehow..

Friiy

I don't have a fuel shutoff solenoid.  Gravity feed from my tank to my new fuel filter/fuel line; good free flowing fuel to the carb.  New gas, no water.  Fuel bowl is filling properly, so the diaphragm pump is working properly.  I can see raw  fuel gurgling out of the jet while it is 'running', as Friiy described above.

I pulled the intake manifold off to check the valve operation in each cylinder - just because I am at a loss...  Good vacuum at each head when the starter is engaged.

Is it possible the the bowl vent is plugged?----   not allowing air into the top of the carb bowl?  

Is it possible the carb Gasket between the two halves is on upside down----   not allowing the air to the nozzel hole of the main Jet?

can you post a picture or two?

how was this thing running before you started working on it?

Friiy

Q- Is it possible the the bowl vent is plugged?----   not allowing air into the top of the carb bowl? 
A- The bowl vent is free flowing.  I've got the air cleaner Assembly off.  I can actually see a small amount of fuel come out of that hole from the vibrations when it's rough idling.

Q-Is it possible the carb Gasket between the two halves is on upside down----   not allowing the air to the nozzel hole of the main Jet?
A- It's on correctly.  I made sure all of the ports were visible when the gasket was put on.  If it was on incorrectly, fuel wouldn't be able to travel from the diaphragm fuel pump into the bowl.

Q- can you post a picture or two?

A- see below.

Q-how was this thing running before you started working on it?

A- I mowed about half my lawn (1 acre), then shut it down to talk to my son.  I couldn't get it restarted because of a bad starter (cracked magnet).  I replaced the starter and still had difficulty starting so I replaced the spark plugs, choke cable (original was seized from the winter) and replaced a burned out diode for the charging circuit.  After all of this, I couldn't get it to run without being choked.  I pulled the flywheel to check the alternator (diode issue) and checked the magneto.  I set the magneto gap to 0.012" after I tightened down the flywheel.

After this the engine wouldn't run faster than an idle while choked.  I checked compression then dove into the carburetor.  The temp of both exhaust pipes are hot several seconds after starting, telling me both cylinders are firing.

Thanks

I got it!  The flywheel key sheared and the fw spun 90*, and I couldn't see it.  Runs like a champ now.

Thanks for everyone's help!

Awesome, glad you got it sorted out! Any idea what caused the key to shear off? In your recap of what led to this, you mentioned pulling the flywheel, but that was after the problems had started. If the key was still intact when you pulled the flywheel, was the flywheel nut torque set too low when re-installed, or something, which allowed the flywheel to spin and shear the key?

I initially pulled the flywheel to check the alternator - I kept blowing diodes.  Apparently I didn't torque the fw enough.  Rule #728: Don't forget to torque yee flywheel  :-)

cool... The fix is even cheap!

Friiy