Export thread

I have a Craftsman mower – model number 917.378550 – that won’t start.
A few seasons ago it had issues of a similar nature and (with the help of this forum, I believe) it was repaired by a simple coil replacement.

It started having similar problems towards the end of last season in that the mower was down on power. I made it through the last few mows by spraying some seafoam in through the air cleaner and that would temporarily give it more grunt.
I put it away for the season and now it won’t start at all. I’m getting spark. I verified this by removing the spark plug, grounding the plug and having my wife pull the cord. I could see a strong spark when doing so.

I assumed my issue was tied to a fuel problem (since I have air and spark), so I removed the carburetor and soaked it in carb cleaner overnight. It still shows no signs of even thinking of turning over. I sprayed some seafoam spray into the chamber, still no start (?). I’m confused at this point.

Any ideas on what my next step of troubleshooting should be?

Have you tried another spark plug?
You need spark, fuel and compression to run.

Spray starting fluid into the air intake. With the air filter removed, try to start the mower. If it starts and then shuts down, you have a fuel problem.

Sorry fellers, I guess I should have tried a new spark plug - replaced the spark plug and now it starts / runs.
I thought the old one was fine because I could visually see a spark, but I guess not.

It still sputters and hesitates on occasion. Could this be due to a vacuum leak? I noticed when the carb was off that the gaskets have seen better days.

Sometimes the plug won't fire under compression although it looks fine when testing.

Sounds like gaskets need replacing. You can squirt some carb cleaner or starting fluid to see if there's an air leak, rpms will change if there is. Best to do it before engine is hot for safety concerns. May have to clean carb again.

if you know someone try a sonic clean but you have to know someone thats go the mechine to do it

but im sure there will be other people that have a few things to try first

Mikel1 said:

Sometimes the plug won't fire under compression although it looks fine when testing.

Sounds like gaskets need replacing. You can squirt some carb cleaner or starting fluid to see if there's an air leak, rpms will change if there is. Best to do it before engine is hot for safety concerns. May have to clean carb again.

Click to expand...

Personally I would never spray any thing from a spray can all over the carb & manifold while the engine is running.
The propellant is very volatile so you are beggine to set the mower on fire.
Please use a trigger pack, a lot safer. WD 40 or similar will also make the engine smoke and do no damage to the engine or your eyebrows.
Water can also be used bit it ends to kill the plug.

bertsmobile1 said:

Personally I would never spray any thing from a spray can all over the carb & manifold while the engine is running.
The propellant is very volatile so you are beggine to set the mower on fire.
Please use a trigger pack, a lot safer. WD 40 or similar will also make the engine smoke and do no damage to the engine or your eyebrows.
Water can also be used bit it ends to kill the plug.

Click to expand...

Fair enough, perhaps I need to tone it down for those who lack common sense. I have used it many, many times with no problems, not bathing the carb with it(targeted) and using on cold engine.
I learned earlier this morning a young man locally was working on a tiller. He spilled gas on top of it then while checking spark, he was set on fire from his stomach to his head.

Always a problem when giving free help.
Some one I was helping with a motorcycle did exactly this with WD 40 from a spray can.
Set the carb on fire followed by the fuel tank followed by the entire garage when he kicked it over so the fuel spewed out all over the floor.
Good thing was the insurance paid out on the garage and the bike and his other 1/2 saw the flash and came in with the kitchen fire extinguisher and put him out.

WD 40 from a trigger pack is good for this application as it wets all the surfaces so will sit for long enough to get sucked in and of course causes copious qualtaties of white smoke if injested.

mrmechanic said:

All the above are helpful hints but it seems the most obvious little things are usually the issues. We see 1000's of mowers a year and most of the time you will find a simple solution. I have come up with a diagnosis tool that might be
helpful to you advanced-power-equipment.com/lawnmowerdr.htm.
Some issues on this forum seem to be over thought. Yes, carburetors are an issue, some can be dealt with but most need to be replaced if it is truly a carb issue. Check the easy stuff first!

Click to expand...

If you and you company think you should buy a new one over cleaning one then you have a issue with your business model.

BlazNT said:

If you and you company think you should buy a new one over cleaning one then you have a issue with your business model.

Click to expand...

Sounds like a good business plan to me .
A lot more profit in selling a complete carb than a rebuild kit.

bertsmobile1 said:

Sounds like a good business plan to me .
A lot more profit in selling a complete carb than a rebuild kit.

Click to expand...

Well that is so true.

bertsmobile1 said:

Always a problem when giving free help.
Some one I was helping with a motorcycle did exactly this with WD 40 from a spray can.
Set the carb on fire followed by the fuel tank followed by the entire garage when he kicked it over so the fuel spewed out all over the floor.
Good thing was the insurance paid out on the garage and the bike and his other 1/2 saw the flash and came in with the kitchen fire extinguisher and put him out.

WD 40 from a trigger pack is good for this application as it wets all the surfaces so will sit for long enough to get sucked in and of course causes copious qualtaties of white smoke if injested.

Click to expand...

S@#t happens, dangerous to use any flammable liquid even if just spraying in carb. I know that from personal experience.
Wd40 I find to be messy because it leaves behind a film to cleanup but different strokes for different folks.