Please identify WHICH Briggs-
Model & Type numbers.

How many gears do you have?
Do you have problems in 1st gear?

Here's the info:

Model 282707
Type 0122-01
Code 951102Za

Well, you answered 1 of 3 questions, so I'll give about 1/3 of an answer-

Does the throttle shaft have any side play in it?
Are the carb mounting bolts tight?

Bill

I will check that out in the morning when the garage is cooler and have daylight. I will let u know then.

Bill

Ok, no play with the throttle cable or the clamp holding it to the motor. The throttle works just fine and throttles down to almost a crawl. Both carb bolts were tight but I still turned them about one turn for a tighter fit. The spring is connected and works.
The plug is new, took it out and had just a very slight blackening, not much. I ran the mower and it seems that once the engine heats up the missing or skipping happens in 3rd and 4th gears, 4th being the worst. I cut on second gear so even if it stays like this it will be ok. I even thought about ordering a new carb until the repair guy said he swapped it with a working carburetor he had and still ran the same.

OK, this is a "SWAG," but, since the fuel circuit has been proved functional, and it runs OK in second gear which seems to indicate compression, valves, etc. are OK, that would indicate "electrical" as the next area to explore. What's different about 2nd gear as in position and wire routing, etc? I'd do a careful inspection for worn, frayed wiring, and electrical connectors. That's a "stretch" as the wiring is primarily from the dash up to the engine compartment and the only wiring down near the shift would be the OPR. For troubleshooting only, disconnect that and observe the result.

Good luck,

Ev

My question wasn't about the throttle cable.
It was the throttle shaft.
This is a nearly 18 year old engine.
Throttle shafts wear and cause a vacuum leak.
This causes the the fuel mixture to lean out and tends to result in a surging condition under load.

I wouldn't consider the USED carb your fixit guy used to be beyond suspicion.

What I would do-
Change the fuel filter. make sure it's the Briggs RED filter.
Put in a strong dose of carb cleaner in the fuel. Since the engine is "almost" running OK, that should clean any gunk/varnish build up on the carb passages.

Also toss in a new spark plug.

That's about the cheapest approach at this time, without doing any major disassembly.

Thanks both for the help. Bill if you could then direct me as to the location of the throttle shaft on my 38" mower.

I took off the engine cover and noticed some light rust on the flywheel where the magnet rides along. I used a small brass wire brush to cleaned it up. Now the pop and miss is just about gone, in any speed. I also checked all the electrical connections and all look good. The sparkplug is new as the repair guy replaced it.

This post was edited by Ernie55 on Fri, Oct 4, 13 at 12:21

The throttle shaft is part of the carb.
It has the butterfly that opens /closes that controls air flow through the carb.
The choke shaft/butterfly is very similar looking, but located closer to the air cleaner.

Suggest you go to the Briggs website and download the IPL for your specific engine.
It'll have exploded views and proper terminology for the part names.

Thanks Bill for the explanation. I do believe that part is ok. It may be just age catching up with the engine? What do you think about the rust I removed from the flywheel face?

The only problem rust has is if the coil doesn't have good ground.
Magnetism is too stupid to be bothered by rust. Electricity isn't.

If I understand, there were two problems:
(1) fuel leaked through the carburetor and contaminated the oil - this was fixed by overhauling the carburetor and changing the engine oil.
(2) it makes a kind of popping and misses except on 2nd gear. This is the remaining problem.

I am trying to understand your description. Here is another thought.
This is a high mileage engine. Perhaps there is an accumulation of carbon in the cylinder. This is a flathead engine. Consider pulling the cylinder head to clean the out the carbon. Also check the valve clearance.

The throttle shaft can look OK, and yet be causing a problem. The shaft rides in bushings that are pressed into the carburetor body, or it simply rides in holes that are drilled into the pot-metal casting. As the engine accumulates hours of operation, the two holes get slightly enlarged, and eventually they become a significant vacuum leak, causing a lean mixture. One fix would be to install a new carburetor, which would have smaller holes, and a tighter fit.

Thanks for the comments but the repair guy put on a different carb which was operating fine on another machine, yet mine ran the same with the different carb. It just may be as bluemower suggested. I will check that out.

Ok so before I tried anything else I cranked it up, sprayed Seafoam in the carb throat, and more Seafoam. It smoked and sputtered a bit but it sounded fine after a couple of minutes. I was able to mow my yard in all speeds with just a couple of small pops so I'm happy with it now. Thanks for all the help.

I'd suggest putting the Seafoam/carb cleaner IN the fuel.
That way it actually cleans the important parts of the carb.

Will do Bill. Thanks again!

Put about 4 ounces of Seafoam in about one gallon or less of fuel and cranked it up and mowed the back lawn..........purred like a kitten. Put 2 ounces into my Husqvarna self propelled small mower and it too purred like a kitten. Must have been junk in the trunk!
Thanks again Bill for your Seafoam suggestion.