[khenderson12588]

I have a Z445 with Briggs & Stratton engine. It recently had a surging issue, but I took apart and cleaned the carb, which fixed that problem. Now the engine sounds fine in neutral but when moving, it seems to run more slowly than it should. Has new spark plugs, filters (air, fuel & oil), oil changed, new trans belt, fresh gas. I also followed the procedure to purge air from the trans system. Not sure what else to do.

 

[laser3kw]

How old is the mower and has it had any regular maintenance? Have you checked the valve lash lately?
It it is lacking power under load, it may be running lean. Start the mower and warm it up, then drive it normally (blades engaged) for a few minute then cut it off without returning to idle. Pull the plug and see what it looks like. Normally, black is rich, chocolate to brown / tan is normal, light tan to sandy is lean-ish and white is too lean.
Did the old trans belt look glazed? Like it was slipping? check and lube the idler / tension pulley and arms to make sure they are moving freely.

 

[khenderson12588]

How old is the mower and has it had any regular maintenance? Have you checked the valve lash lately?
It it is lacking power under load, it may be running lean. Start the mower and warm it up, then drive it normally (blades engaged) for a few minute then cut it off without returning to idle. Pull the plug and see what it looks like. Normally, black is rich, chocolate to brown / tan is normal, light tan to sandy is lean-ish and white is too lean.
Did the old trans belt look glazed? Like it was slipping? check and lube the idler / tension pulley and arms to make sure they are moving freely.

It's a 2013. I bought it a year ago and the owner kept pretty good service records. I'm no mechanic, so not sure what I would be looking for on the valve lash.
I will try what you suggested and check the plugs. I know the old plugs were black.
Trans belt wasn't glazed, just slightly frayed. That was my first thought as well, but replacing it didnt change anything. Pulleys are moving freely.

 

[laser3kw]

The old plugs were black from running rich and surging. Now that you cleaned the carb, check again.
Don't be intimidated, it is fairly easy. Do a search on utube with your engine size and model. I suggest always getting a new valve cover gasket. All you need, generally, is a socket and a set of feeler gauges. You will also have to find the valve lash measurement in the manual.
Does the trans have a filter?

 

[khenderson12588]

The old plugs were black from running rich and surging. Now that you cleaned the carb, check again.
Don't be intimidated, it is fairly easy. Do a search on utube with your engine size and model. I suggest always getting a new valve cover gasket. All you need, generally, is a socket and a set of feeler gauges. You will also have to find the valve lash measurement in the manual.
Does the trans have a filter?

Got it maybe I can figure it out.
The trans oil reservoirs have foam inserts under them that i assume are filters, is that that you mean?

 

[laser3kw]

Some transmissions have an actual can type filter that is serviceable like a car oil filter. I would have to look at the service manual for the machine or the transmission to determine the procedure for oil change / service / purging.
good luck - keep us posted.
PS - the model and serial for the engine is usually on the engine itself in the form of a data tag or stamped into the shroud or valve cover. You will need that to order parts and find the correct specs for engine service. The trans some times have data tags on them or you have to go to the machine manufacture to determine the trans type. Hydrogear is a common trans and their web site is very helpful.

 

[laser3kw]

BTW - I have to go radio silent until Sunday evening.
If you need help, post up and I'm sure one of the others will chime in.

 

[khenderson12588]

BTW - I have to go radio silent until Sunday evening.
If you need help, post up and I'm sure one of the others will chime in.

So I just got back to work on this today. Ran it about 30 minutes and checked the spark plugs. The right one was black, the left one still looks completely clean. So looks like maybe the connector on the plug could be bad? Both plugs are brand new.

 

[laser3kw]

So I just got back to work on this today.

I would run it for a short while, shut off, and check each head for heat. I temperature gun is good, but a check with your hand will work - caution - burn hazard.
Black is running rich, clean may not be firing.
please post the model and serial for the engine is usually on the engine itself in the form of a data tag or stamped into the shroud or valve cover.

 

[khenderson12588]

So I just got back to work on this today. Ran it about 30 minutes and checked the spark plugs. The right one was black, the left one still looks completely clean. So looks like maybe the connector on the plug could be bad? Both plugs are brand new.

So I just got back to work on this today. Ran it about 30 minutes and checked the spark plugs. The right one was black, the left one still looks completely clean. So looks like maybe the connector on the plug could be bad? Both plugs are brand new.

I would run it for a short while, shut off, and check each head for heat. I temperature gun is good, but a check with your hand will work - caution - burn hazard.
Black is running rich, clean may not be firing.
please post the model and serial for the engine is usually on the engine itself in the form of a data tag or stamped into the shroud or valve cover.

Here's the model/serial. Might not get a chance to run it tonight but will update asap.

 

[laser3kw]

Thanks for the info. It makes research a lot easier
If you do find a cold / not firing cylinder, swap the coils and see if the dead cylinder follows the coil
good luck

 

[khenderson12588]

Thanks for the info. It makes research a lot easier
If you do find a cold / not firing cylinder, swap the coils and see if the dead cylinder follows the coil
good luck

Well I switched the coil from the firing cylinder to the non-firing and sure enough, it fired right up. So looks like it was the coil. Im going to order a new one and hopefully it's good to go. I'll update when I replace it. Thanks for the help on this!