44S777 engine shutting down under load

Nlcowand · Jun 30, 2018

I have B&S 44s777-0011G1 engine on a husqvarna lawn tractor. It is not running correctly. After cutting grass for 10 minutes it starts acting up and shuts down. It is then hard to start and won’t run under load. If I wait about 15-30 minutes it starts up fine and will run rather smoothly for about 5-10 minutes under load and shutdown again. I have eleminated the fuel filter, air filter, gas tank vent and water in the fuel as a possible cause. I have drained the bowl and the gas I’m using is fresh.
I would appreciate any kind of direction you may offer as to how I should proceed with troubleshooting this issue.
Thanks!

Rivets · Jun 30, 2018

Next time it shuts down check for spark on both cylinders. You may have what is called a hot short or open, which means when the coil gets hot it will either open up or short to ground. No spark until it cools down.

tom3 · Jun 30, 2018

How old is this machine? I wonder if the fuel supply hose is being attacked by the gas we use these days? Swells up inside and reduces flow? Something to look at maybe. Ignition, as Rivets suggests, might be the culprit though.

Nlcowand · Jun 30, 2018

Rivets said:
Next time it shuts down check for spark on both cylinders. You may have what is called a hot short or open, which means when the coil gets hot it will either open up or short to ground. No spark until it cools down.

Thanks for the reply!
After it shuts down under load it will start back up somewhat rough, but once I engage the blades it can’t handle the load and shuts down. Would this be the case with a bad coil?
Thanks

DennisRSmith · Jun 30, 2018

Great thread

Rivets · Jun 30, 2018

Here’s a test that give us a better idea of what may or may not be happening. Next time it happens, if you have a GOOD insulated pliers, start the engine (I know it will run rough) and pull the plug wire on one side. Does anything change? Go to the other side and do the same thing. If the engine speed changes when you pull the wire, that cylinder is firing properly. If nothing changes, something is wrong with that cylinder. You now have to check for spark on that cylinder, to see if we have a spark or fuel problem. If both cylinder show a speed drop, then we will go after a fuel problem. I’ll be in and out this weekend, but will try to check back as often as possible.

Nlcowand · Jun 30, 2018

I went and tried that and when I pulled the left side plup cap nothing happened. When I did right side engine died. So I guess I have a bad left side Magneto...or am I over simplifying this.
Thanks

tom3 · Jun 30, 2018

Swap spark plugs and see if the problem follows the plug.

Rivets · Jun 30, 2018

Now we have narrowed it down to that cylinder. Next two things to check. If you have an in-line spark tester, see if you have spark when it is running rough. After that test pull the plug and see if it is wet. No spark and wet plug probably the coil. Dry plug, I would be looking at a fuel issue. Let me know what you find and we’ll go from there.

Nlcowand · Jul 1, 2018

Rivets, thanks for reply. You have been very helpful.
Ok, this morning I was able to check it out. Cranked it up and ran till it shutdown. Put inline tester in place and checked plug and I am getting a spark.
Pulled the plug and it is dry.

44S777 engine shutting down under load

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