B&S 12hp I/C Starting Troubles

Old 04-26-05, 09:11 AM
Visiting Guest
Posts: n/a
B&S 12hp I/C Starting Troubles

Well, first off, I know that I have a dirty carb issue...but I have finally used enough carb cleaner to at least get my engine to run before it stops again.

Let me detail the situation:

Initially, the mower wouldn't turn over, so the obvious choice is to get a new battery. Done...but the mower still doesn't want to turn over very easily, sounding like it has to struggle and strain to turn the crank shaft. Ok, so I figure perhaps I have the wrong sized battery and I get out the charger/starter to attach to it. This does help, but it still doesn't want to turn over easily, sometimes seeming to freeze up before turning again (while starting). At this point, I figure I can live with hard starting, if I can just stop fuel from pouring out of the carb...This is of course due to a stuck fuel float or something similar, so I get the carb cleaner and spray everything as best I can through the air filter opening and the fuel inlet. The choke seems to open and close with no difficulty, so I consider the cleaning to be a success. Well, it still leaks fuel so I try again and again to clean it, finally going so far as to empty the fuel tank and put a few ounces of pure carb cleaner in there to let it 'leak' out the carb. I also spray through the fuel filter as well as spraying the spark plug clean with the carb cleaner. After letting everything sit for a little while to dry, I go through a few cycles of opening the fuel line to let the carb cleaner do it's thing. The leaking finally stops and I am happy. Now, I get on and turn the ignition while having the charger/starter attached to the battery...it turns over as easy as pie with no straining whatsoever! Now we're running on pure carb cleaner for a little bit, but finally the engine dies. I figure I should probably put some real gas in the tank and I do, diluting the cleaner by about half. But....after that initial success...it is getting harder and harder for the enginer to turn over again, with the strain returning....still using the charger at this point and it still will turn over and run for a second or two...but that's it.

My real question is if the hard starting is truly a symptom of the carb being dirty, or perhaps something else? My spark plug is fairly fouled at this point...could the lack of spark make it so difficult for the engine to turn over? Does the energy have to 'flow' through the plug to enable starting? I have no doubts that I need to do more work on the carb, but the hard starting is what troubles me the most.


Old 04-26-05, 11:12 AM
puey61's Avatar
Join Date: Apr 2004
Location: Upstate New York
Posts: 3,224
Received 0 Votes on 0 Posts
What make and model engine do you have? First, you need to check you don't have a siezure-in-progress happening. Remove the spark plug(s) and grab ahold of the flywheel screen and see if you are able to turn the engine over easily by hand. Hopefully you can. If not, have you ever let the engine oil get dangerously low? And now you have a near siezed engine! If it does turn over well post back with the engine make and all ID numbers of such and we'll continue on.
Old 04-26-05, 08:48 PM
cheese's Avatar
Forum Topic Moderator
Join Date: Jul 2001
Location: USA
Posts: 17,635
Received 55 Votes on 50 Posts
From your description, the engine is hydro locking because of the fuel leak. The fuel leaks into the cylinder, and the engine has a hard time getting past the compression stroke because fuel doesn't compress. Be careful if you spin it without the spark plug in it. Fuel can blow out and if the plug wire sparks, it will blow a fireball out the front of it if fuel shoots out.

Cleaning the carb the way you're doing it won't work. There is stuff in it that needs to come out. Disassembly is the only way to do it.

Your oil is also probably full of gas now, and the engine shouldn't be run until it's changed. If the carb leak is not stopped, the oil will continue to be diluted with fuel.
Old 04-27-05, 07:56 AM
Visiting Guest
Posts: n/a
re: carb leak

Sounds like you hit the nail on the head Cheese...the engine has never been used while low on oil, so that possibility is excluded.

I know that I need to take the carb apart to clean it, but my relative inexperience in this area is holding me back. I'm not even totally certain -how- to take it apart, though I have a Repair manual from Briggs and Stratton. At this point, I feel I can possibly take the fuel bowl off without messing it up too badly, but beyond that I am out of my element. I'm tempted to just buy a new carb, but at $136 a pop, I'm not so sure I want to do that either...

For reference, the model is 281707, and type is 0415-01. If my reading of the parts list is correct, the carb part number is 491031.

If it turns out I need to do more than just clean the float and such by removing the fuel bowl, I'm afraid I'll need to have a professional do the job...at a price of around $60. This of course assumes I can get the carb off in the first place...Thankfully I can at least rule out an ignition problem. I bought some fresh oil yesterday and I will change that out when I've got the carb problem fixed. I've also got a new spark plug and fuel filter waiting to go in.

Thanks for the responses.

Old 04-27-05, 11:13 AM
Join Date: Mar 2005
Posts: 432
Received 0 Votes on 0 Posts
To remove the carb,

1 remove air fileter and air filter tray.
obviously, shut off the fuel or drain it
remvoe the fuel liine, linkages then look at the bottom, there shud be a little metal piece bolted to the block, take it off and finnaly, there are two bolts/screws holding the carb to the block right at the intake, remoove and presto.
to clean the carb, once it is off and emtied out
flip it over and find the bowl, there is a 1/2 inch nut with an adjustment srew holding it on, carefully remove it and then using compressed air and carb and choke cleaner clean the bowl, float, seat and needle valve, also check if u have a pin hole in the float as this wud casue the prblem you are describing.
hope this helps

Thread Tools
Search this Thread
Ask a Question
Question Title: