18HP Briggs shooting fuel out top of carb

11 years ago

Hi all, I recently picked up a Murray 46" riding mower that has been sitting for a few years. Engine model: 422707, Type: 1263.01, Code 9501185B.

I cleaned the mower all up, removed and cleaned the fuel tank, replaced fuel line and filter, removed and cleaned/checked plugs/gap, put new gas in and fired it up. It starts really hard (like the starter is struggling), but once it catches it lights off easily. After letting it idle for a bit, I noticed it was running rough. Both cylinders seem to be firing (removed plug wires while running form one cylinder at a time and it runs worse, etc..) but it was idling like a Harley and there seemed to be fuel pooling in the bottom of the intake manifold.

Purchased a carb rebuild kit, disassembled and cleaned carb thoroughly with gumout and compressed air. Replaced the needle (old one had rubber tip, new one was steel) and the seat (was a pain to pull old one and drive new one in). Checked the float (no gas inside it). Didn't remove the main jet at the bottom (was not included in the kit) but I did clean it thoroughly with carb cleaner running through it. Replaced all fuel pump components, went well. reassembled and installed on mower. (No air filter or housing installed for testing purposes) Here is where the excitement comes in:

Started the mower and it idled better than ever (that is until I noticed fuel just SHOOTING out of the hole circled in the picture below). That pic is a photo I found on the web, my carb is much cleaner! :-) I shut it down immediately and was able to see fuel running down inside the carb and pooling in the bottom of my intake manifold just like before.

Suggestions?!

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Comments (9)

tomplum
11 years ago
The needle should have the rubber tip. 808798 is the part #. It will have two needle valves in the kit, pick the right one.
Slowcorrado
Original Author
11 years ago
Thanks, only had the steel one in the kit? I could put the old used one back in perhaps. Doesn't the seat have to match the needle as well? (Which is why I changed the seat)
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tomplum
11 years ago
What part # did you use? A solid seat w/ no viton insert should use the viton tipped valve.
Slowcorrado
Original Author
11 years ago
I used Briggs original carb rebuild kit # 694056. Interesting you're saying this because, the new seat was solid brass just like the old one, and there was no viton to be found anywhere. I did however have a few parts left over from the kit. In the pic below, I do question the o-ring and small flat brass washer.. no idea where they should go. Thanks for your help so far!
tomplum
11 years ago
I should have noted by the date that yours was an older model. The numbers that I had listed do not apply. Your float valve does have a viton tip- just that it is grey in color. The good news that your float is adjustable and should be set level with the top of carb inverted. You can even cheat a little and lower the level of the fuel in the bowl slightly. Some of these like that and spit less on accel. One thing that I found is that the little wire on the valve can be installed either way in the float. Furthest away from the float pin is best. In the end though, you may want to verify the assembly order of the pump components. I have done that one once myself and created a flooding condition as the fuel tank was under the hood. The valve part # without the seat is 394681 should you wish to try another.
Slowcorrado
Original Author
11 years ago
Here's a pic of the float as it was removed from the carb. Based on what everyone is saying, it's COMPLETELY wrong. :-) Now, I took another look and it seems my new needle does have the Viton end (It was just a silvery grey). So, after bending the tab a little on the float, I can't seem to get it to come up at all. I'm worried about bending it too much. I'll post a follow up pic of the needle/seat area.
Slowcorrado
Original Author
11 years ago
Here's a detailed pic of the needle area. Do I have this installed properly? and am I allowed to bend that tab on the float a lot more? It seems like it's so much further than it was designed for. Also, look at the seat. It's slightly recessed in the top of the carb. Since I didn't have a manual stating how deep to drive it in, I set it at the depth of the previous one (which could have been wrong!)

This post was edited by Slowcorrado on Fri, Apr 5, 13 at 18:26
tomplum
11 years ago
I guess all you can do is try to make up for it by bending the tab. You can buy the seat kit 394682 and try again. I use a small router shaft thingie w/ a flange that will only let it press in to level with the casting
Slowcorrado
Original Author
11 years ago
Update: I bent the tab further and was able to level the float (held upside down). Installed it, started it up and VOILA! no more pouring fuel. Yay! It didn't run totally right, seemed to actually go lean a bit as it would run somewhat better with the choke partially on. So, I fiddled with the only adjustment screw. (I'm guessing the idle mixture screw?) and set it 1.5 turns out from seated. Now it seems to run/idle pretty smoothly. I don't have much reference on how it should sound, but driving it around the yard it never lost power at all. Now, to get the deck reconditioned and actually try to mow with it! Yay!