Runs fine then stalls----- HELP!
 

My trusty old 1811 has been a champ until lately. It cranks and runs fine for about ten to 15 minutes and starts surging and will eventually stall unless I pull the choke all the way out. Here is what I have already done. 1. drained and cleaned the tank. 2. Put on a new fuel filter. 3. removed and cleaned the carb and flushed out all of the jets. 4. Tested the fuel flow from the tank with no filter to see if it was good and it was. 5. Checked both plugs and they were clean and light grayish.6. Disconnected the fuel line from the carb to test the pump output and got just a little flow but no big pulses or squirts. Is that normal? 7. Tried the fuel line with no filter but no help.
When it starts up it idles fine and will run perfectly and then, usually on a hill or a sharp turn it will surge and then stall. I checked the float and needle and they seemed fine. I was a little puzzled by the float because it appears that it will only move up or down just a fraction before the plastic tab on the arm makes contact with the carb body. Is that right? Any ideas?
Thanks:beerchug:

Your comment on the float moving only a fraction got me thinking about my snowblower that was having a similar problem except it would seem like it was running file until you loaded it up and then it surged. On my snowblower the float needle was intermittently sticking and shutting off fuel flow when it should have been allowing it to flow.

Can anyone say if the float tab on the end of the arm should face up or down? I took the fuel pump off to check the diaphragm and it only had a little rust on the engine side of the piston. It has to little check valves that pump and suck the fuel. When I took it off they fell out and I do not know the direction that they go back in. Can anyone tell me? The diaphragm looked good with no tears in it. I also tried to run the engine with gravity only and it would not run unless I put my hand over the intake to create vacuum. Otherwise there was no fuel flow through the filter. Tomorrow I going to move the fuel tank to a higher level and try the gravity plan again. I'm narrowing it down to two possibilities and they are the fuel pump and the float/needle valve connected to it. Any other ideas?

Rudy, I ran my 1811 for 2 years without a fuel pump. Did you check the tank screen, fuel valve and lines?

Same with my 1872, ran fine gravity fed.
goodluck

Is the gas tank cap venting properly?:bigthink:

Thanks for the ideas. I did check the tank for debris and totally emptied it and then refilled it with new gas. If I open the bottom valve it runs out profusely. I took the gas cap out completely and it mad no difference. If I covered the carb intake then I could see gas flow into the filter but not without creating a vacuum with the carb. I am thinking it might be the float valve that is sticking but cleaned it really well. What is the down side to running it without the float in place just for a test run? What is the up/down side going to an electric pump? Thanks for the help so far. It looks like the float could go in either way and I was wondering if maybe I have it upside down. Does the smooth side go down or up? If the bumpy side is down then the little tab on the end of the arm hits the carb body when it tries to open the valve. It will open but not very much. When you guys say gravity do you mean with the tank where it is normally or do you raise it? I could not get any fuel to flow with a straight hose from the tank to the inlet on the carb.

If you take the float out chances are it won't run. Itll just completly flood itself with raw fuel ... the pump should put out pretty good. I havnt read everything in the thread but have you tried bypassing the fuel pump (line from tank to carb) with a full tank...see if it runs then. I'm sorry I'm not familiar with the carb you have to be much help on the specifics of it

Edit. Just read your whole post... you should have flow if the fuel level is higher then the carb...im full tank

Rudy, on my machine the pump went bad and flooded the crankcase with fuel. I just ran a new fuel line from the tank to the carb (with a gravity type filter) and nothing else. If you keep it above a 1/4 tank the level will be above the carb and it should flow fine. I did run a jumper hose on the failed pump from inlet to outlet because it was leaking oil. I ordered a new pump but never installed it because it ran fine. Have you looked in the Kohler manual on setting up your float to the proper specs?

Todd, I did run a hose from the tank to the carb and kept it under the manifold and under the carb so that it would not get above the lower part of the tank. It would not flow and I am suspecting the float/needle valve as the culprit. The thing runs beautifully while there is gas in the bowl but when I make a sharp turn or go across the hill then it starts to surge and stall. That would lead me to believe that it is the float. I do not have access to the Kohler carb settings but will look for them. Thanks for the info Todd.

Do you have a Kohler adjustable carb or a Wabro fixed main jet carb?

Grrrrrrrrrrrrrrrrr!!!!!!!!!!!
 

I solved the problem! Boy am I mad! I cleaned that Wabro carb five times and didn't think there was any place left that could harbor debris. I was wrong. I did what some of you suggested and went gravity this morning and of course it ran fine and sounded like the 1811 of old. And then I took it on a short mow and surging and stalling started after about three minutes or the amount of fuel in the carb bowl. So I knew at that point that it was either the float needle or the seat because the fuel flowing from gravity alone would have run a Chevy truck. I took it all off once again, I'm really fast at removing the carb now, squirted carb cleaner into every orifice but decided to take off the little elbow fitting where the fuel line attaches to the carb. I looked in the hole but could not see anything but silver metal. Then I noticed a little tit of black sticking up out of the seat where the float needle goes. I poked it with a tiny screwdriver and what looked like a fleck turned out to be a flake of old rubber that had made itself part of the needle seat. It would allow carb cleaner to pass but when the needle went back in, the passage way became very tight and only allowed a small amount of fuel to the bowl. I mowed about thirty minutes with it so I know it is fixed but I am not sure where the air valve on the top of the carb should be set. Do any of you have that setting? I tried it out and in but it didn't seem to make much difference. I set it at two and one half turns out from full in. BTW, there are several slots in the bottom of the top engine area where the tin meets the engine and I dropped two parts in one of them. I took off the top exhaust engine tin and found them and then pressure washed the fins and the front of the engine so at least some good came from my ordeal.:beerchug:

Can you post a picture of what you are calling the air valve?

My carb has two screws on it. One for the idle speed and this one.

End of the story. Today I added a Faucet electric fuel pump I bought on line for $25. Hooked it up and turned it to run but not start. It clacked for a few seconds and then I hit the starter. Bam! No cranking and no choke needed. I hooked it up through the hour meter circuit and will add a 3 amp fuse tomorrow. It was real easy and I bolted it to the top left, the fuel line side, side of the engine with an existing bolt.

18 Series Cub Cadet Runs great, then stalls
 

You may have already remedied your stalling issues but I thought that I'd give you one additional place to look. It sounded like you and I cleaned the carb completely, and pretty much the same way; yet we both still had trouble.
After checking fuel flow TO the carb., I removed the bowl and as the float just hung there, I opened the fuel valve to see exactly how free the fuel flow was inside the bowl. It was terrible! (Which was Great news)
It was not the fuel line, or the filter, or the tank or tank screen; it WAS the fitting screwed into the carb! I removed the fitting and ran a Q-tip into that fitting and it was packed with debris. It all made sense. As the engine "cooled" (which had Nothing to do with the problem), the bowl fuel level had time to catch-up, so she started right up. Hopefully this helps!