Export thread

I have a 26hp Briggs and Stratton 44P777 on my craftsman garden tractor.
I recently changed the carb and fuel filter. Now the engine runs rough, produces black smoke, and spits fuel into the air filter. I changed the oil and filter thinking there may have been some fuel in the oil.
I have found that I can sometimes mess with the choke (at the carb) and get the engine running smooth, but only a very short time.
Any suggestions?

thegoaltender said:

I have a 26hp Briggs and Stratton 44P777 on my craftsman garden tractor.
I recently changed the carb and fuel filter. Now the engine runs rough, produces black smoke, and spits fuel into the air filter. I changed the oil and filter thinking there may have been some fuel in the oil.
I have found that I can sometimes mess with the choke (at the carb) and get the engine running smooth, but only a very short time.
Any suggestions?

Click to expand...

Find out why the choke is closing by itself.
Once you get the choke to stay off it will run ok.
My guess is you put something on wrong when you installed the new carb.

OK, so the float moves freely. The engine runs fine at the lower third of the throttle setting. Once I increase the throttle beyond the lower third it starts to spit fuel up into the air filter.

what made you replace the carb in the first place?

There was no fuel getting into the bowl of the old carb

The problem is most likely that the choke is closing at higher rpms. There is a choke return spring that is probably not keeping the choke open. My susgustion is to test it by taking a small peice of wire/zip tie or something else and tie the choke in the open position. If this solves the problem then you have a starting point. Below is a link to the parts breakdown. Let us know if this helps

Parts and Diagrams for Briggs and Stratton 44P777-0025-G1

originalswampfox said:

The problem is most likely that the choke is closing at higher rpms. There is a choke return spring that is probably not keeping the choke open. My susgustion is to test it by taking a small peice of wire/zip tie or something else and tie the choke in the open position. If this solves the problem then you have a starting point. Below is a link to the parts breakdown. Let us know if this helps

Parts and Diagrams for Briggs and Stratton 44P777-0025-G1

Click to expand...

Thanks for your help!!!!!!
I just took apart the carb again.
I am confused regarding the choke return spring. Should I be able to see it without removing the choke valve? How does the choke return spring move the choke valve when it is controlled by the external connection?
I will try and find something to hold it open, but still don't understand how it could possible close...

Ok!! now I have confused myself. If there is a choke cable on the engine it should not be able to close itself you are correct. I guess that in the past when an engine floods itself enough to get fuel in the air cleaner it has always been a choke problem. Let me know where I am wrong these are my assumptions.
1. The engine cranks and runs fine at low rpm.
2. After you rev it up it starts to run rough and spits gas into the air filter.
3. It is a Briggs and Stratton twin v engine.

Let me know where I'm wrong

originalswampfox said:

Ok!! now I have confused myself. If there is a choke cable on the engine it should not be able to close itself you are correct. I guess that in the past when an engine floods itself enough to get fuel in the air cleaner it has always been a choke problem. Let me know where I am wrong these are my assumptions.
1. The engine cranks and runs fine at low rpm.
2. After you rev it up it starts to run rough and spits gas into the air filter.
3. It is a Briggs and Stratton twin v engine.

Let me know where I'm wrong

Click to expand...

Those assumptions are all correct!

is the air cleaner stuff off?...so you can see the choke plate?....if so...does the choke start to close as the rpms are maxed out?

Does your mower have a seperate choke or is it incorperated with the throttle? The ones thatare incorperated with the throttle operate via a slot in the linkage. There should be a plastic fitting that the choke rod is attached to. That can come loose fairly easily, causing the choke not to work right. The ones with the seperate choke control,I feel are much better in that they provide control of the choke plate much better.

Just curious but when was the last time you adjusted the valve lash on that v-twin ohv. Carbs don't usually spit fuel out of the throat unless its being blown out. I would suggest you pull both spark plugs and do a compression test and see if both cylinders are within 5% of each other. Check your valve lash for proper .004 clearance on 1/4 inch past TDC. Put an inductive tach on both spark plugs while running to verify RPM or whether it is firing or not. A Twin will run on one cylinder but it will run rough as you say.

jameswsr said:

Just curious but when was the last time you adjusted the valve lash on that v-twin ohv. Carbs don't usually spit fuel out of the throat unless its being blown out. I would suggest you pull both spark plugs and do a compression test and see if both cylinders are within 5% of each other. Check your valve lash for proper .004 clearance on 1/4 inch past TDC. Put an inductive tach on both spark plugs while running to verify RPM or whether it is firing or not. A Twin will run on one cylinder but it will run rough as you say.

Click to expand...

Jeff - The choke control is separate from the throttle control.
Reddragon - The choke plate is unable to close on its own as it is held in place by the external choke control
Jameswsr - Well now we are getting beyond my knowledge. I kinda learn as I go along. The engine is only a few years old with about 90 hours on it. Do I need more than a compression tester kit for the compression test? More than a feeler gauge & in-lb torque wrench for the lash adjustment? More than the Induction Tach for the RPM measurement? I do have a simple inline spark tester similar to this (Amazon.com: Lisle 20610 Inline Spark Tester: Automotive) that shows both cylinders have spark. Any suggestions on which tools might be better for the testing would be appreciated as well.

Thanks so much to everyone!

Jim

if thats so...then i would say its flooding...maybe the float needle not seating ....or sometimes a bleeder passage will plug and more fuel is suck through the main or primer passage...was your fuel pump replaced too?.....also is this a new carb or a new used one?

I'm hoping someone can help me with a similar problem I am having with my 21hp. I recently replaced a cracked fuel line running from the pump to the carb. Following the repair, the motor ran as described in the title, varying speeds at full throttle and spewing black smoke as it revved up again.

Upon disassembly of the air cleaner housing I noticed everything below the carb throat was soaked with gasoline and the air cleaner was saturated also. A small brass port appears to have nothing attached to it at the top of the carb, but if I am missing a hose, where did it go and what does it attach to? The port spews fuel only when the engine is shut down.

I can't seem to find any schematics to assist me. I have included a video of my problem. Thanks in advance for any assistance you can provide.

Briggs and Stratton 385777 - YouTube

that port is a vent....i think you need to take the carb off and clean it....[ rebuild kit is about$45]....i just did a carb just like that....i would also replace the intake manifold o-rings that touch the head....on this carb ..youll need a some sewing needles to clean very small bleed holes....make sure you dont tear the old gaskets if your want to reuse them....tell us how it turns out:thumbsup:

Thanks, RD

Is this a common carb? or is it specific to this engine? What would be a good source for the kit?

I'm a complete amateur when it comes to this but I imagine it could not be too hard to remove and go through the carb. Or am I wrong?

its not hard....you just need to keep everything clean and do a thorough job of inspection.....this is one link online... Lawn Mower Parts, Small Engine Parts & Much More! | PartsTree.com - Briggs, MTD, Toro, Cub Cadet, Husqvarna, Troy-bilt... ....but a local shop could serve you better.....just get "all" the numbers off the engine when sourcing parts....theres a 100 different versions of everything on mowers.....so the numbers are your key......usually with those carbs,you'll want to remove the cables [marking their location with a black marker].......and the air inlet pieces....then undo the bolt to the head and take the carb with intake manifold off as one piece and go from there:thumbsup: