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

This is a strange problem.  I walked away a year ago now try to work on it again.   I am running out of ideas.  I have an old Homelite generator using a B&S 243431 10HP engine.  It has good compression (75psi) and sparks but wouldn't start.  I have a new iginition coil as well.   I sprayed the starting fluid into the spark plug still no luck.  Not even trying.  I see sparks when having the spark plug sitting against the engine block. The only possibility is the sparks are "weak".  I can't really tell.  Is it possible?

What do you think?  What else I can try?

Thanks
Bob

Could be a timing issue. If it doesn't spark around TDC then the compression and spark aren't happening together like they should. That can happen when the flywheel key shears. Wouldn't think that would really happen with a generator though.

75 PSI seems a bit low.  i would try squirting some oil into the cylinder to see if the compression goes up and it may start then = temporarily.  This would indicate need for new rings.

I don't think 75 is low. Most engines these days have a compression release to make starting easier so you can't get an accurate reading.

if you have spark, compression, and good fuel it should run. sounds like you have the spark. I would make sure you have fuel getting to the cylinder.

I sprayed the fuel to the cylinder directly.  That should not be the issue.  I have another engine with 50 psi compression and no carburetor.  It starts right away with fuel sprayed into the cylinder.
I will check the flywheel key issue tomorrow.

Bob,  Off chance you have a low oil shut down circuit????  Only other thing I have JD gen with a 10hp Briggs and I have a switch on the pull start housing and on the main panel that both need to be in the on position (red part of the toggle switch showing).  I've pulled many a times to pure sweated out shirt before realizing the engine switch was off
Just guessing.

Sheared flywheel key would be my guess. Marc

1. try turning engine over 10-15 times
2. then remove spark plug and see if its WET or DRY with fuel??

3. if its DRY then u need to look at the carb and fuel delivery system. (remove fuel line going to carb and check for good fuel flow to carb..
4. if YES then the carb or intake gaskets are the problem..

5. if spark plug is WET then u have and igntion problem. (either a bad coil not likely because its new.. or bad spark plug.. or the ignition timing is off.. check flywheel key, and to do that u need to remove flywheel and visual inspect the key... and before removing flywheel MAKE SURE SPARK PLUG IS WET!!! because plug should be wet if the timing is off!

I have never seen a timing issue on a generator, you can't electriclly dump load on them quick enough to shear a key. If the flywheel has come loose, it may shear a key. Don't laugh, but i think it is the plug. ( if i had to guess) .. You may see spark now, but as pressure increases in the engine the resistance of the air fuel mix becomes greater,the plug may be fouledto a point that the resistance throught carbon on the insulator is less than the resistance throught gap. Thus not firing under compression load.. When we check aircraft spark plugs and clean them, they are we tested in a controlled pressure /windowed box for such a reason. Try swaping out the plug and let us know. Good luck, Friiy

friiy wrote:
In all of my years and experience with numerous small engines, I've only had two spark plugs fail.  Both sparked outside the cylinder but would not fire when installed.  A new plug was the fix.  If the OP is putting fuel directly into the cylinder via the spark plug hole, the engine should fire if there's spark.  If it fires and runs for a bit, the electrics are good.  If it doesn't fire, something is amiss in the ignition system.  I'd start with a new plug, then check the plug socket/lead and work backward into the coil/points/cdi, etc.  The low oil switch has confounded many a novice.  If the engine has one, ensure the oil level is up.  If oil level is good, disconnect the switch and try to fire the engine.