Unable to start mower

[yannick]

Hi Team,

I have a B&S 500e powered lawn mower. I have only had this thing a couple of years or there abouts, so not very old at all. I went to start it a couple of weeks ago and couldn't get it going. Been sat in the shed a few weeks prior and was working fine. Have noticed a few months back that it was getting harder and harder to start. Anyway, I've had it apart. Have cleaned the carburetor, although it was mint inside. I have checked the oil level. I checked the armature resistance and got a reading of over 6Kohms ( I read that these should be between 2.5 - 5Kohms. Not sure how accurate that is?). So I ordered a replacement which reads at 8.45Kohms, so I am assuming the readings on these are not necessarily reliable to go by? The gap recommended on the manual for the armature is between .006 - .014 in, so I went inbetween at .010. I also replaced the spark plug. Still, I get not start. I get backfires occasionally, but not even a hint that it wants to go. I am a bit stuck at this point.

Thanks in advance!

 

[hlw49]

Diagnose the problem don't throw parts at it hoping that is the one that fixes it. Oh I forgot that is the process of elimination. First determine why it won't start. Is it an ignition problem or a fuel problem. Todays ignition modules are like this they are either good or bad most manufacture don't give any specs. Sometimes you will get one that won't fire when it gets hot. Check for spark. Take a spark glug and open the gap up to 1/4 inch and if spark jumps the gap it is good. Oh yes you have to ground the body of the plug against the engine block. If it has spark spray a little gum out carb. cleaner in the carb. If it starts and dies them it a fuel issue. Probably a carb. issue. Hope this helps.

 

[bertsmobile1]

The auto choke on thee POS B & S engines gives no end of problems
Make sure it is closing fully when you are trying to start the cold engine

 

[Scrubcadet10]

remove the air filter cover and filter, spray some carb cleaner, starting fluid or dribble some gas right into the carb, and see if it will fire up on that, Now:

1. If it runs and dies, fuel delivery issue
2. If it Runs and continues to run fine, i'd suspect what Bert said.
3. No run at all, i'd unplug the small wire from the ignition coil. that is your kill wire which creates a path to ground for the coil, killing spark. If it starts with that unplugged, the wire insulation got a visit from Jerry and Tom didn't know or the switch mechanism is bad.

 

[yannick]

Diagnose the problem don't throw parts at it hoping that is the one that fixes it. Oh I forgot that is the process of elimination. First determine why it won't start. Is it an ignition problem or a fuel problem. Todays ignition modules are like this they are either good or bad most manufacture don't give any specs. Sometimes you will get one that won't fire when it gets hot. Check for spark. Take a spark glug and open the gap up to 1/4 inch and if spark jumps the gap it is good. Oh yes you have to ground the body of the plug against the engine block. If it has spark spray a little gum out carb. cleaner in the carb. If it starts and dies them it a fuel issue. Probably a carb. issue. Hope this helps.

Thank you for your response. Will give the diagnosis another go, but your pointers were helpful. Will report back with my findings.

 

[yannick]

The auto choke on thee POS B & S engines gives no end of problems
Make sure it is closing fully when you are trying to start the cold engine

Hi @bertsmobile1, thanks for getting back to me. Which part on the engine is the auto choke mechanism?

 

[yannick]

I don't believe my mower has an auto choke. It has a throttle control. I checked to see if it opens fully and closes when moved to full throttle and closed throttle.

 

[StarTech]

In order for anyone to know exactly which engine you have we the actual model, type, and date code.

Now with being that small of an engine I assume you have a walk behind mower. IF so check the flywheel key as it can be partially or fully sheared. Do this especially since is back firing again assuming you mean out of the carburetor.

 

[yannick]

In order for anyone to know exactly which engine you have we the actual model, type, and date code.

Now with being that small of an engine I assume you have a walk behind mower. IF so check the flywheel key as it can be partially or fully sheared. Do this especially since is back firing again assuming you mean out of the carburetor.

High @StarTech, appreciate your response. Yes, a push mower with a small engine, only 140cc. Here is the link to the manual, this is according to the details printed on the engine (Model: 90000) - https://bsintek.basco.com/BriggsDocumentDisplay/default.aspx?filename=ngjxDEW9p8ZVj5K1w

Yes, the backfiring is coming out from the carburetor. I have not checked the flywheel key as of yet, so that will be my next task. The manual does not give the torque setting for the flywheel. Might have to use my deflector torque wrench to find the torque when releasing the nut.

 

[StarTech]

It should be 60 ft-lb for that OHV engine.