B&S 6.5HP Quantum S Low idle + weak

[Mr_Accord]

I have a 6 yr old Craftsman Lawnmower with a Briggs and Stratton 6.5 HP Quantum series engine. Since last year the engine hasn`t been running that well hard starts after primming (usually takes one pull, now at least 4x) and the same when turning the engine off for a min after using for an hour it would be a pain to get it going again. So decided to take a quick look at the carb to determine if there was any [censored] in the bowl or on the float but it was surprisingly clean and I use the mower a lot. But now when using it I find it isn`t as loud as it should be and it feels like the blade isn`t turning fast/hard enough, it is really weak and this is after an oil change with AMSOIL SAE30+airfilter+champion Plug. I have a second mower and it is a newer 6.25 B&S basically the exact same engine and it is louder and overall more powerful at the moment than the 6.5.

Do I have to adjust the governor? or is it something else? I`m car savy but when it comes to small engines i have no idea!

Thanks.

 

[Deltona_Dave]

I would suggest running some Sea Foam or MMO in the fuel to see if that helps the hard start. Are you running fresh gasoline? E-10 gas is notorious for allowing water to accumulate in the gas. Try some Techron in the gas, as the needle valves may have a little glop in them. All are very inexpensive. Sta-Bil Marine formula may help also.

Dave

 

[yeehaw1960]

After a few years, some quantum Briggs engines governor springs get stretched out. Part of the spring is curled and part of it is straight. Put a slight bend in the straight part and see how it runs out. The taughter the spring (bigger the bend), the faster the engine will run, but don't over do it. Putting some Sea Foam into the tank is a great idea after you get it running at the right level. Will clean up the areas you can't see very quickly.

 

[cos]

yeehaw1960,

Where is the governor spring located?

 

[Mr_Accord]

Thanks I will try adjusting the governor spring. Also I always put fresh gas in my mower and its nothing but regular along with stabil for winter storage. As for a seafoam treatment I have a new can in the back of my garage, how much SF do you need to do a treatment on a small engine?

 

[yeehaw1960]

Don't make fun of me cos. I'm old and senile! The spring attached to the throttle.

 

[RUSHCO]

Do you have a throttle cable or a fixed speed throttle control. If it is fixed there is a small tab that the spring hooks to. Bend that tab so the spring is tighter therefore you will get more rpms out of the engine. Don't go to far as max is normally 3600 rpm.