Any small engine 'xperts here?

[Pete M]

My 6.0 briggs/stratton on my craftsman lawnmower won't stay running unless you continuously prime it (and it runs pretty decent when you do). The gas and oil are fresh and the spark plug is clean. I've cleaned out the "carb" and soaked it in carb cleaner. I've checked every gasket and o-ring I can find and can't locate any leaks. Any thoughts on what's next?

:mad:

[mvusse]

Needle valve in the float bowl might be stuck closed.

[WahooSteeler]

did you run all your fuel out for the winter or put fuel conditioner in? those needle valves can get really gummed up if not. did you take the carb apart when you cleaned it?

[Pete M]

Yuppers on all of that WS. Every year I run it out of gas, then dump in some fuel stabilizer and run it dry again. Just to be extra sure. :D Everything inside was spic and span when I first opened it up so when I say I "cleaned" it, I really didn't accomplish much of anything in the process. I can be quite the stickler when it comes to preventative maintenance.

 

Anyways, well it works now. I re-disassembled the carb 'cause I had a feeling that the screw in the bottom of the bowl was supposed to be aligned so the hole at its base lined up with another hole in the bowl. Or something like that. Carbs really ain't my thang. But while I was in there this time the pin that holds the float fell out and the float fell to the ground. So in the end, I'm not sure if it was the alignment of the holes or if the needle was properly seated in the float (took some effort to reassemble). Either way I'm happy because now I can cut the doctors' lawn across the street (as per our deal that lets me store my junk in his parking lot). :cheers:

 

And not that it helped much in this particular instance, but B+S has a great website with a lot of troubleshooting tips.

[carnuck]

DON'T run regular grade gas in any small engine! The additives put in over the past 2 or so years are destroying these little motors by drying everything rubber out and wearing out all the bushings. Same goes with the oils since the zinc has been ripped out making LE grade oils that are killing flat tappet cams at a 300% higher rate than just 2 years ago.

[jtdesigns]

DON'T run regular grade gas in any small engine! The additives put in over the past 2 or so years are destroying these little motors by drying everything rubber out and wearing out all the bushings. Same goes with the oils since the zinc has been ripped out making LE grade oils that are killing flat tappet cams at a 300% higher rate than just 2 years ago.

 

Then what oil and fuel do you use?

[Pete M]

For better or for worse, I use high grade synthetic oil. :D (left over after each oil change in the diesel libby)

I too am curious as to what carnuck uses.

 

 

And on a side note, I dragged home a discarded lawnmower yesterday. :roll: Same generation craftsman as mine, but with a 6.5 engine and the one "drive" wheel. Don't know what's wrong with it, but I figured with all my newfound mower knowledge I might as well give a try. :D

[carnuck]

premium gas and racing oil (it still has zinc)

[comancheman]

this deffinetly makes sense but why are the manufacturers still recommending 87 octane in these motors?

[Randy in Maine]

If you have a plastic fuel tank, you can run it dry. If you have a metal tank, leave it full of stabilized fuel. I use regualar gas and regular 30 weight oil with no issues.

[carnuck]

this deffinetly makes sense but why are the manufacturers still recommending 87 octane in these motors?

 

Hello? If it only lasts a year, you'll be buying a new one! It's called planned obsolescence (if you call their phone line, most will tell you to use the better fuel) Fuel is also different over the past few years.

 

If you have a plastic fuel tank, you can run it dry. If you have a metal tank, leave it full of stabilized fuel. I use regualar gas and regular 30 weight oil with no issues.

 

Used to be that was enough. We supply a lot of small engine repair shops and they are experiencing major problems with all the small engines due to oil changes and fuel changes.

[james750]

Check ur high and low needle adjusments along with idle adjustments. a needle valve could be stuck too lean or rich.

 

When i raced irok goped scooters i always used MS98 98 octane race fuel that i purchased at the local drag strip. This is the best stuff to use in any small engine. most performance small engines require 94+ octane fuel and no higher than 112 octane. also, check to make sure the throttle flap inside the carb is not sticking just a little bit, this can cause the engine to bog until it is warm enough to run.

 

Hope this helps.

 

PS:this probably isnt the problem, but it could be a weak spark due to a out of place magneto. the best way to measure and space the magneto is to loosen it, place 3 pieces of paper between the flywheel and magneto, and push the magneto down onto that and tighten the screws, remove the paper.