# B&S push mower 6.75..Help?



## hilljack13 (Oct 23, 2008)

I did a search and didn't find anything that seemed to help my problem. I have a B&S 6.75 engine on my push mower, bought this year in March so it's only 7 mo old...Heres my story.

After cutting the yard a few days ago I go to crank it one more time to go over a spot I missed and there is a loud "POP" and didn't start. I tried a few times and it "Pop, pop, pop" and wouldnt start. I put it up and called a local shop and he said it sounded like my carb my be gunked up. The fuel I have is not old, maybe a few weeks but I just got finished cutting so it wasn't sitting. Anyway, in the past few days I change the spark plug, air filter, and got one of the Carb overhaul kits and did that today. All it does is putter when I pull the cord to start. I'm out of ideas on what it could be and I'm no mechanic either. 

Also just to note on the B&S website I read somewhere to take the spark plug out and put a tablespoon of gas in, replace the plug and try to start. I did that and all that managed was to soak my muffler with gas, it ran right out the bottom of the muffler. Obviously it didn't start.

any help is greatly appreciated.


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## manic (Aug 2, 2005)

Keep the spark plug out of the machine, hook it up to the plug 
wire. Let it dangle and touch the head, something metal on or near
the spark plug hole. Pull rope, see if you get fire ie, spark coming
from spark plug. If you dont get spark, you have some sort of ignition
problem. If you do get spark, try and run a compression test on the
cylinder. If you dont have a compression tester you can try and put
your thumb over the sparkplug hole and pull the rope, if you feel pressure
pushing and and sucking in, you know you have some compression.
If you feel very little pressue it could be a internal problem with the
cylinder/piston. If you have fire the gas in the spark plug hole should
have worked, it would have ran for a bit anyway....


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## hilljack13 (Oct 23, 2008)

Thanks for the reply. I don't think I'm getting a spark from spark plug, I took it out and hooked it up to the wire and when Cranked it I couldn't see anything. I tried this under the crawlspace where it's dark. Also when I did this some gas did come out of the spark plug hole. When I put the spark plug back into the lawn mower the muffler blew white smoke the first two strokes then nothing. Also was going to ask should I replace the muffler since it got a dose of gas in it from the other test?


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## hilljack13 (Oct 23, 2008)

hilljack13 said:


> Thanks for the reply. I don't think I'm getting a spark from spark plug, I took it out and hooked it up to the wire and when Cranked it I couldn't see anything. I tried this under the crawlspace where it's dark. Also when I did this some gas did come out of the spark plug hole. When I put the spark plug back into the lawn mower the muffler blew white smoke the first two strokes then nothing. Also was going to ask should I replace the muffler since it got a dose of gas in it from the other test?


I need to change this...I do get a spark. I couldnt see it the first time b/c of the angle I was looking from. It was orange in color if that helps. Also maybe not much here but I put a piece of paper towel in front of the spark plug hole and it blew about a foot in front of the mower when I tried the spark test again.


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## MrChooks (Apr 19, 2008)

hilljack13 said:


> Thanks for the reply. I don't think I'm getting a spark from spark plug, I took it out and hooked it up to the wire and when Cranked it I couldn't see anything. I tried this under the crawlspace where it's dark. Also when I did this some gas did come out of the spark plug hole. When I put the spark plug back into the lawn mower the muffler blew white smoke the first two strokes then nothing. Also was going to ask should I replace the muffler since it got a dose of gas in it from the other test?


:wave: OK - on the muffler question - No - a bit of fuel getting in there shouldn't be a problem - so if it was otherwise OK I would just leave that.

As you have compression and seem to have spark - (whilst it might be time to replace your spark plug with a new one or at least clean the old one) - the engine should start.

If the plug is in fair condition it should be dry and a grey / brownish colour on the electrode end. If it's black or covered with oil - then that indicates either fuel mixture or oil burning problems - but as you said the engine was working fine until this problem occurred - I am leaning toward an ignition or plug issue. 

So try the "fuel down the plug hole trick" again - BUT only use about a teaspoon of fuel. Too much in there and it wont start because the mixture will be too rich.

So turn your fuel valve on, put about a teaspoon of fuel in the plug hole and quickly reinstall the plug, put the choke on to your normal start setting and give the engine a few more tries.

If it doesn't start - pull the plug again and put another spoon of fuel in and try again for a few times. The engine should fire as if they have fuel, compression and spark - they just have to go.:grin:

If you can get have it running - even if roughly - let us know how it is performing and we can chase through any other issues then.


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## k2skier (Sep 30, 2008)

If this is an overhead valve motor, I would pull the rocker cover and see if both valves are opening and closing. I've had a couple that just "pop" when pulling and priming, and one of the valves wasn't functioning. It also may have sheared a flywheel key.


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## hilljack13 (Oct 23, 2008)

I have tried all the above again with no luck. As for an overhead valve motor I have no clue, The model of it is 126T02 0675 B2 if that helps. I'm ready to start taking the thing apart but I don't have a repair manual so if I mess something up I guess I'll have a nice project on my hands. I only wanted to cut the back on last time before storage so I have all winter to work on it.


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## k2skier (Sep 30, 2008)

It's not overhead valve. Check your flywheel key, you will need a flywheel puller. That's if a shot of starter fluid in the throat of the card doesn't do anything, I try not to have to resort to putting fuel directly into the cylinder, very easy to flood them that way. You may have to pull the cylinder head and check valve operation.


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## hilljack13 (Oct 23, 2008)

I began to take my mower apart this morning and as I get deeper into it I'm noticing gas is all over everything. Gas tank is off at this point as well. The area that is a larger circle to the side of the valves was covered in gas, each time I wiped it off it appeared to have more leaking from behind somewhere. Also the breather assymbly was soaked along with the gasket. 

Also not sure how normal this type of buildup is but on the Arm. Magneto it is covered in a brown gunk, nothing else has this. From what I can tell the flywheel is clean but I haven't got to taken that area apart yet.

I can try to put up some pics if that will help.


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## MrChooks (Apr 19, 2008)

:wave: hilljack - there shouldn't be fuel all over the place - sounds like the needle / seat float valve is stuck open. If your engine has a little bowl on the bottom of the carb - take it off and gently exercise the float up & down. The fuel should flow freely when the float is down and stop completely when the float is up. Try this and see if you can flush about 1/2 cup of fuel thru the float valve as that sometimes clears any little piece of muck that might be stuck there -Remember - this is a NO SMOKING job :4-thatsba


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## hilljack13 (Oct 23, 2008)

MrChooks said:


> :wave: hilljack - there shouldn't be fuel all over the place - sounds like the needle / seat float valve is stuck open. If your engine has a little bowl on the bottom of the carb - take it off and gently exercise the float up & down. The fuel should flow freely when the float is down and stop completely when the float is up. Try this and see if you can flush about 1/2 cup of fuel thru the float valve as that sometimes clears any little piece of muck that might be stuck there -Remember - this is a NO SMOKING job :4-thatsba


Don't worry about the smoking..thats just nasty :grin:...Also a few days ago I already took the carb off and did an overhaul on it. Cleaned it out and all. I'm really lost on what's causing all this.

Another question though. on the carb throttle, I have two, one is always open and one is closed, depends on the arms that move them. Since I'm no mechanic it would seem right that they are both closed or open? How should they be set?


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## MrChooks (Apr 19, 2008)

:wave: One is the choke - which would be closed when you start cold - the other is the throttle - which adjusts when you look for more power from the throttle control.

They both work by restricting the airflow thru the carb venturi thereby increasing the vacuum in the venturi and that increases the amount of fuel that gets sucked into the inlet airflow.

If you have fuel still leaking - then I would suggest that it's the needle and seat (valve) that is operated by the float. If it has something stuck in it or is damaged - fuel will flow continuously - hence fuel finds its way all over the place. You need to get control over this fuel flow else your engine will never start:sigh:


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