B&S 550 EX stopped - won't restart

Look in your gas can for the best starting fluid. Most engines are made to run on unleaded gas. 2 stroke mix covers every gasoline engine you could possibly own. Blowers, trimmers, edgers, mowers, boats, cars and trucks.
 
BobbyC777 said:
My 2013 Troy Bilt 21" push mower has been running well. But recently after running for about 2 minutes it stalled. It restarted twice but ran for only about 20 seconds - did this twice. I assumed carburetor problem even though I run ethanol-free gas. I took carb off, did normal cleaning, replaced but no luck. It would not even attempt to start even using starter fluid. Here are some steps that I have taken:
  • verified that I have spark by grounding plug to block and using recoil starter
  • replaced spark plug with B&S product
  • replaced coil twice - one cheapy and one B&S OEM 84005272 (properly oriented up/down)
  • undid kill wire from coil
  • set armature gap to 0.012"
  • verified that flywheel magnets are strong
  • verified that flywheel keyway looks good but have not removed flywheel yet
  • compression feels good. Checked with gauge. Get 60 PSI on first pull, goes to 70 PSI on 2nd and 110 PSI cranking it for a few seconds with electric drill.
  • removed carb (again) and shot starter fluid directly into intake port - no luck
  • removed valve cover and verified proper action of rockers/pushrods
    • have not checked valve lash other than to verify that some clearance at TDC
On the surface I have spark (at least outside the combustion chamber), fuel (starter fluid) and compression but it doesn't fire at all.

A couple of additional data points:
  • after sitting for a few hours, the first pull sounds like it gets maybe one minor combustion but it could be my imagination. Subsequent pulls yield nothing.
  • I have spent hours on this and twice it did start with starter fluid and ran for 4-5 seconds (sounded normal). Both times the carb was not even on the machine! But this was only twice out of 100+ pulls.
Fortunately I was able to borrow someone's extra old flathead machine so at least I can keep the lawn mowed.

I have not had any blade impacts. But I have a gut feel that somehow either the ignition timing is off or that the valve timing has changed,
As stated above, I have yet to remove flywheel or check valve clearance. Short of those 2 things I am out of ideas. I would not know how to verify that valve timing had gone bad.
Strange that it fired & ran twice on starter fluid with carb off but only twice out of many, many attempts.

All suggestions appreciated!

Bob
Click to expand...
"....even though I run ethanol-free gas". False virtue.
 
Auto Doc's said:
Hello B.,

Sounds like you got water or grass clipping in the fuel tank somewhere along the way.

Pull the upper cover and remove the fuel tank and empty the fuel into a clear glass jar to check for water separation or debris. Then blow low pressure air back into the fuel hose nipple to clear it out.

I find this happen on a regular basis because the fuel and tank are the last thing people consider to be an issue. Never assume the "new" fuel in your gas can is "sterile" of water or debris. Check your fuel can well for trash or water floating around in the bottom.

Don't forget to pull the carburetor bowl off and empty it, that way you return everything to a dry condition before adding fuel.

Getting clean fuel these days is becoming a challenge in some parts of the country.
Click to expand...
🙄. No.
 
BobbyC777 said:
can you elaborate?
Click to expand...
Certainly....at the introduction of ethanol in 1978 there were problems with rubber components. Buna N solved all that by 1980. Almost every automotive or small gasoline engine since then has been placarded for at least 10% and later some for 15%. Ethanol will not harm these engines despite the wives tales. If you want confirmation read this...it will take some dedication as it's pretty long. 4.5 is the section of interest....

Gasoline FAQ - Part 1 of 4

Gasoline FAQ - Part 1 of 4
www.faqs.org
 
BobbyC777 said:
Thanks! Sounds like ethanol is getting a bad rap! I will read all this later today as I have yard work to do after wind storm last night.
Click to expand...
There are only two negative sides to ethanol....the first is that it is hygroscopic meaning it picks up water from the ambient atmospheric contact. That isn't much of a problem at the percentages used. The other is that it assists in washing the oil off the cylinder walls. Gives the oil ring much less to do and the top rings wear a tiny bit faster but isn't really that big a problem. Now the good part. If you were to run an engine on pure ethanol (carburetion or injection must be changed to meet the stoichiometry of the fuel) that engine runs far cooler because of the latent heat of evaporation. In the 70s used to run two stroke snowmobile engines on pure methanol. It wasn't uncommon to find frost on the cylinders and carb after a run/race....but methanol is nasty stuff and can kill you.
 
You must log in or register to reply here.
Back
Top