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Walbro carb trouble...HELP


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09-25-08, 10:37 AM   #1  
Walbro carb trouble...HELP

Hi,

I bought a 99 Craftsman lawn mower that wasn't running. It had fuel in the crankcase so I drained that. Then I soaked the carb and made sure no crud was in any of the holes using small wire. The needle was damaged so I replaced that.
The engine will start and run as long as I squirt gas in the carb. There is fuel in the bowl but not a drop getting to the carb when I crank it over. I know this is gravity feed but shouldn't the crankcase vacuum pull from the carb.?? The fuel solenoid is working. It has good compression also. It is on a 14.5 briggs.
Thank you for any help you offer.


Last edited by hoosierdaddy58; 09-25-08 at 10:38 AM. Reason: forgot to describe eng
 
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09-25-08, 12:01 PM   #2  
Please post the model type and code number off of your engine.

Gravity feed fuel systems are just that, and if fuel is not getting into the carburetor then there is a problem with the fuel flow or inlet in the carburetor.

How did you determine the fuel solenoid was working properly??

 
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09-26-08, 01:28 PM   #3  
Model # is 287707, type is 1255-E1 and code # is 99041920. With the key turned to run, I unplugged and plugged in the solenoid switch. I can hear it click when I do that.

 
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09-27-08, 01:00 AM   #4  
What did you soak the carb in? Can you spray carb cleaner through the main jet and see it enter the carb throat?


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09-27-08, 10:06 AM   #5  
I used carb cleaner to soak it in. I can spray in the fuel inlet and it comes out the needle and seat hole. I can also spray in the main jet and it comes out in the carb. That's what has me stumped.

 
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09-27-08, 09:22 PM   #6  
Something in it is still clogged, or you have a large vacuum leak between the carb and head.


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09-28-08, 04:18 PM   #7  
I don't think it's a vacuum leak. I can feel air being sucked into the engine when I put my hand over carb. while cranking it. I soaked it for 10 hours in carb. cleaner. Is there anything else I could do to get it unclogged?

Thanks

 
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09-28-08, 05:20 PM   #8  
I would remove the fuel solenoid and physically check the operation when power is applied.

 
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09-29-08, 09:17 AM   #9  
I took fuel solenoid off and checked movement. When the key is off, the plunger is up. When I turn the key on, the plunger goes down.

 
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09-29-08, 09:54 AM   #10  
Well the next thing I would check is the nozzle. Remove from the carburetor and make sure all the passage ways and orifices are clear and you can see through them.

 
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09-29-08, 10:12 AM   #11  
Is the nozzle the part that screws through the center of the carb?? If so , I tried to unscrew that with no luck. The threads are messed up where the fuel solenoid threads into the carb. The solenoid goes in fine and gets tight, but the nozzle won't come out the same threads.

 
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09-29-08, 07:54 PM   #12  
Yes, thats the nozzle, if you can't get it out you may want to at least try running a small pilot wire all the way up until you can see it come out inside the carburetor. There must be something in the nozzle preventing fuel from flowing through.

 
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09-30-08, 05:06 AM   #13  
Does it have a new fuel filter?
Remove solenoid from bottom of bowl and see if gas dribbles out bottom.
thanks,

 
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09-30-08, 06:10 AM   #14  
I can see through the nozzle into the carb. It's as clear as it could be. The bowl holds gas and the solenoid works. This is driving me crazy! Yes it does have a new fuel filter. There's no problem getting gas to the carb. I don't know what else to do with this carb. I know I don't want to buy another one, but I may have to.

 
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09-30-08, 06:33 AM   #15  
Are you getting power to the fuel solenoid when the key is in the start position??

You may want to try the carburetor with just a bowl nut in place of the fuel solenoid to see if it will draw fuel that way.

 
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09-30-08, 01:11 PM   #16  
Is the float needle moving freely? If it is dragging or sticking it would prevent fuel flow. Polish the float needle and the seat it fits in with metal polish and a Q-tip.

 
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10-03-08, 10:43 AM   #17  
Yes the fuel solenoid plunger goes down in the run and start key positions and goes up when the key is off. I will have to buy a float bowl nut and try that.
I put a new needle in and the seat looked ok. I cleaned the seat when I put it back together. The needle does move freely in the seat.

 
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10-03-08, 11:52 PM   #18  
Is the hole in the side of the post that drops down from the carb clear? It may have a brass jet screwed into it, or some are just a drilled hole in the aluminum carb.


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10-08-08, 02:32 PM   #19  
Cheese .....Thank you,Thank you, and Thank you. The jet located on the pedestal was totally blocked. Put in a new jet and it started right up! I am still new at this. That's why I look on this site for guidance. I am learning more on each mower that I get running. Thank you to all that answered this post.

 
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10-09-08, 12:19 AM   #20  
Great! Glad we could help!


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10-09-08, 01:38 PM   #21  
Ok, one small problem and I will consider this a success.
The engine starts and runs "good". There is a popping noise that comes out of the carb. every 10 to 20 seconds. It doesn't slow the engine down. I have checked the plug gap, it is at .030. The armature gap is at .010. I took the breather off and when the carb. pops, a mist of gas comes out of it.
This is a walbro carb. on a 14.5 hp Briggs. I have the valve clearances at .004 on intake and.006 on exhaust. The govenor seems to work ok also.

Thank you

If I close the choke partway while it is running, it smoothes out and no popping. As soon i let the choke open, it goes back to popping.


Last edited by hoosierdaddy58; 10-09-08 at 02:43 PM. Reason: Left out some one detail
 
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10-09-08, 05:25 PM   #22  
Applying a little choke smoothing the engine operation would indicate too lean carburetor setting. Since this carburetor is not adjustable, there must still be some restriction in the metering jet in the carburetor. You indicated you replaced the jet, or possibly the nozzle in your carburetor.

Are you sure you replaced it with the correct one? This type of carburetor is used on many different displacement engines, the only difference on the carburetors used on the different engines many times is the jetting.

 
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10-10-08, 07:18 AM   #23  
There were two main jets in the kit I bought. I put the bigger one in this time with the same results. I took the air cleaner off to watch the throttle plate movement. When I move the throttle cable lever up or down, the throttle plate doesn't move at all. Is this how it should be? When it is running, the govenor moves, which opens and closes the throttle plate slightly. If I hold the throttle plate closed a little bit, the engine runs smooth. Could it be running lean because too much air is being pulled into the carb with the plate wide open?? I was looking at the govenor spring(weak spring?) as a possible culprit.

 
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10-10-08, 01:46 PM   #24  
You can't see the throttle plate with just the air filter out, you must be looking at the choke plate. If you remove the air filter assembly then you could look into the carburetor throat and see the throttle plate, it's at the back end of the carburetor next to the intake manifold. You may want to try performing the static governor adjustment and then check to see how the engine performs.

 
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10-10-08, 08:49 PM   #25  
To me it still sounds like you have some carb restriction, especially knowing the carb was bad enough to have that one jet blocked completely. I think the restriction is likely to be in the nozzle that you couldn't get out. Aside form the large hole that goes through the center of that nozzle, there are several very small jets in the sides of that nozzle that go to other circuits in the carb. If any of these are blocked, you could have problems like you've described.

Also, does yours have a brass screw that goes in from the top side of the carb? If so, this has jets in it as well and can cause your problem.


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