Outdoor Power Equipment (Lawn Mowers, Snow Blowers, Chain Saws and more) Discussions

I have been working to get an leaf loader ready for fall clean up. The 11hp briggs and stratton engine starts briefly when choked and then dies. Gas runs out and drips below. It runs all of 3 seconds before it dies. I've tried starting it without the choke but no luck there. When I bought it a week ago the previous owner started it on the first pull. It has a good spark, fresh gas, a clean air filter. With the spark plug pulled I can see the spark. I've tried starting it at half throttle, full throttle and low throttle. No difference there. I took the bowl off the carburetor and cleaned out the crud that was in there. Do I need to take the carb off and completely clean it? What setting should the throttle be at for start up? Any suggestions? the motor is a Briggs Industrial Plus model 256422 type 1015 -E1

I'll work on getting some pictures of the carb. I know that there are some hole that I could not reach without removing the float (I did not remove the float because I did not remove the carburetor from the engine, I've never taken one off a Briggs and I was worried I'd ruin something. On the outside (air intake side) of the choke plate I found some small hole to clean. But I have a feeling that there may be more of these holes further in near the other (throttle?) plate. I could not reach those. This afternoon I pulled it and it ran (rough) for almost 10 seconds. &
Question: When I slide a small metal wire down the hole on the left side of the carb it goes all the way in. When I try to do the same on the hole on the other side it only will go in 2 inches. (Cycled in green) I'm not sure if this is normal. <BR><BR><BR>&gt;<BR><BR>This is the location (yellow square) that I could not reach without removing the float. &lt;BR&gt;&lt;BR&gt;&lt;BR&gt;&gt;&lt;&lt;

The holes on the carb are the emulisfier vent and the carb bowl vent.. I could not tell you which is which unless I had more pictures. The holes go in so far and then are drilled 90 degrees through the access behind the welch plugs (silver discs pressed into carb body).

The carb bowl vent keeps the carb bowl and fuel at static pressure (outside air pressure)the low pressure of the air in the venturi draws fuel through the main and low speed jets...

The emulsifier jet is a port that injects air into the main jet fuel stream (through all the little holes in the nozzel) so the fuel "sprays" instead of bubbling up and pooling in the bottom of the venturi..

Don't worry about the wire not going through. Just spray in the hole and make sure it comes out the vent above the float and the emulsifier jet comes out where the nozzel screws in...


Good Luck,

Friiy

friiy wrote:

When I look into the carb while pulling the starter I don't see gas being sprayed.  Instead I see it bubbling up and pooling around the top of the brass nozzle. Right behind the choke butterfly  where the brass nozzle pokes up and enters the carb.  Where is the venturi?

  

The spray shouldn't happen till the engine is running. On Choke-starting with a pullstart, a large vacuum is created to draw "rich amounts" of fuel into the venturi..

The venturi is the narrowing throat of the carb in the middle...(as air velocity increases at the venturi, pressure decreases, thus drawing fuel through the jets to the low pressure area)

I don't understand, is the carb still flooding when it starts to run, or is it acting like it is running out of fuel? Was fuel bubbleing out of the carb as it stopped?


Friiy

friiy wrote:
I oppologize for my poor description. I'm starting to understand how a carburetor works (thank you). With the choke I can see a small wet area forming in the "ventury" area where the brass nozzle sticks up. Then engine starts and then stalls. Previously, when the bad fuel pump was dripping gas down the side of the engine I thought the gas was coming from the throat of the carb (flooded) but the plug was always dry. I ran some more carb cleaner through the little holes and then blew them all out again with the compressor. The engine roared to life and did not die. It ran and ran and ran until I tried to bring the engine back down to an idle. Then it cut out. I'm going to look for the factory settings for the idle screw. PROGRESS!

Well, back to square one. When choked the engine springs to life and as you open the choke it rev faster and faster until it dies about 5-6 seconds later. Pulling the choke back closed again does not keep it running. Nor does changing the throttle. I'm back to the drawing board. I am learning though.

I you can start the engine and only run it on choke, and the carb is still full of fuel when you take the bowl off (provided you have not pumped more into from try to pull start it again). Then the problem is mostly still in you high speed circut. I think you should check the nozzel again, after you clean the nozzle, clean the little hole that goes into the carb tower that allows fuel to enter the nozzle, this little hole(main jet) should intersect with the smooth area of the nozzle...

The hole you need to clean is just above the yellow box on the cutaway carb photo just below the float(aug 30, post picture).. this would be the "main jet" that all fuel travels in the carb..( this jet may be a press in, unremovable or screw-in)

http://outdoorpowerinfo.com/repairs/images/kohler_walbro_lmk/_main_jet.JPG


This photo shows the "main-jet"


Friiy

friiy wrote:
I think I was gettting my "nozzles" and  " jets" mixed up.  I will take another look at the main jet.  My recollection was that there was just a hole there in the aluminum casting, with no jet in there.  But I might have missed something.  I am going to get a tool at lunch today to remove the carb.  Cleaning down low on the ground where it sits is next to impossible while still attached to the engine. 

I think you will be fine if you just take the float off and clean it from there. The nozzel is considered by most the main jet... Really it is the "highway" for the main jet. All fuel is drawn through the calibrated hole that is on the carb tower that intersects with the nozzle. At low speed(low airflow thought the carb) the draw is too small to pull full through the nozzle, At this speed of airflow the throttle shaft is nearly closed, Air has to speed up by the edge of the nearly closed throttle butterfly, thus causing fuel to be sucked/drawn from the little holes nesx to the butterfly on the inside of the carb(low speed) orifice..

Jet and orifices are usually used interchangebly. I think the best description is "low speed circut" and "high speed circut"...


Friiy

Any Progress Underdog???