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Discussion Starter · #1 ·
I just finished rebuilding my Walbro WF carb on my 1974 Panther 340. I set both screws on the carb to 1 1/2 turns out. I also made sure (when the carb is held upside down) that the float is 1" from the gasket by bending the small lever.

The sled started just fine after the fuel was drawn through the carb. I was able to ride it around after it warmed up for a few. Drove it for about a mile then when I came to a stop the motor dies. I have to wait about 3 minutes before it will start again. If I try starting it right after it dies it will not start.

My guess is that when I come to a stop the engine floods since I can't start it right away. Would that be your guess?

Suggestions on what to do to fix the problem?

Also, could someone tell me what should happen when the screws are moved in or out...?

Thanks.
 

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Depending on the age of your WF, it may or may not have two screws on the top near the front of the carb.

The smaller of the two screws is the Low Speed Mixture Screw and if you turn it clockwise, it will lean the mixture. The initial setting should be 1 1/4 open from gently seated.

The second one, the larger of the two screws (if your carb has it depending on age) is the Air Bleed Screw. Intial setting for it is 1/8 to 1/4 turns open from gently seated. Turing this screw clockwise richens the mixture.

On the side of the carb, you will also have a stop screw which can be adjusted up and down to set your idle speed. Acts as an adjusting stop for the throttle plate lever.

Both the Low Speed screws and Air Bleed screws may need to be fine tuned after the engine is up to temp.

I know that you adjusted the float level correctly, but when you reinstalled the float assembly, the spring that fits over the float pivot shaft needs to be preloaded 1 1/4 turns in the direction of the closed position of the needle valve.

Also check to make sure that enrichment lever (the shorter top lever above the throttle lever) is fully closing.
 

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jdwyk...
I'm having the same issue with a Walbro WF-19 (on a Kohler340). I put a new gasket kit in, set the float and preloaded the float spring. It has lots of power in higher rpm's but does not want to idle with any load on the engine. If I remove the drive belt , it runs ok. It seems to be starving for fuel. The WF-19 has only 1 needle setting. Is this similar to your problem?
I'll be keeping a close eye on this thread and will definitely post back when the problem is solved.
 

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Discussion Starter · #4 ·
I don't know if I'm flooding or starving...

I am going to reset the screws 1 1/4 out from seated and then 1/4 open on the air bleed. (what is the purpose of the air bleed?)

I am going to start and let it warm up. Run it a few laps around my horse pasture and then see what happens and then go from there. If it stalls and won't start what should I change? I am going to pull the plug to see if they are wet. If they are then I have a flooding issue correct?
 

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Discussion Starter · #7 ·
Well I reset the air screw and idle screw... Replaced the fuel filter and was able to run it for about 5 minuets then it died when I was going about 30mph. Sat for a minuet and it started right back up. Ran for 30 seconds then died. Sat, started, rand repeat. The more i ran it the shorter the time it would run then die.

I put brand new plugs in and got the same results.

The lights do not work with the bat. out. but it does run with the bat out.

Am I looking in the wrong spots? Should I be looking at the head gasket?
 

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When it stops pull the plugs out and lay them on the head and see if they are fireing. I think you are staving for fuel. Can you blow air back into the tank through the fuel pickup line? You may or maynot be able too. Many sleds have a pickup filter with a oneway check valve in them and that may be all gummed up. The more you run it and the shorter the run time sounds like it is sucking the fuel restriction in harder.
 

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Discussion Starter · #9 ·
I just put a new filter on yesterday because I thought it may have been clogged. It has new fuel lines on it... It's almost like there is a temp sensor on it and it cuts the motor out if it gets to hot. But I've never heard of anything like that. But I think you're right that it is starved for fuel.
 

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Discussion Starter · #10 ·
I am looking at the wiring diagram and see that there is a thermal switch on or near the engine. It is connected to the Temp light. Could this be the cause of my problems? If it gets to hot will it open the circuit causing the motor to die?

I also noticed that the sled likes lower RPM's and when I mash on the throttle it will bog down. But If I ease it up to full throttle it wont bog down.

I still find it odd that I can run it for a short period of time and then it dies. I really hope I can find the fix soon. I am as frustrated as the Elephant Man trying to put on a turtle neck.

Thoughts?
 

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Like ELT said,
-Check for fuel flow
Before you start it, check for spark... (just take a spare plug and shove it in the boot, then hold it against the head)

After it dies, pull a plug check for wetness and check again for spark (while it's still hot). This should determine if it's a sensor issue/if its flooding/starving...I would think.
 

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Discussion Starter · #12 ·
Had it on a jack stand... ran it for 3 miles at 50 - 60mph no problems... took it to the ground and went 2000 feet and it died. Waited 1 min. or so and it started back up....

Any thoughts?
 

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Just a guess, but when you have the back end raised it ran ok for a long time, when it's sitting or running level it stalls. Could it be a float level issue?:dunno:
 

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Had it on a jack stand... ran it for 3 miles at 50 - 60mph no problems... took it to the ground and went 2000 feet and it died. Waited 1 min. or so and it started back up....

Any thoughts?
ELT may have nailed the problem for you.

The Walbro WF on my Li'l Whip was a pain, but mainly because it was finicky.

I had TWO fuel delivery problems on my Li'l Whip, and one fed into the other. The fuel pickup clunker in the tank had a check valve that was sticking, and I, like a moron; ran VINYL fuel lines.

The WF PULLS the fuel from the tank, so when the clunker was sticking and it was hot under the hood, the inlet line would partially collapse. The sled ran leaner and leaner, slower and slower.... then would stall. It always started right up after a few pulls. It was a nuisance to diagnose because we couldn't see the collapsed fuel line when it was at home, being checked out. It would only do it under high fuel demand. We found it with the back of the sled chocked up, high RPM's.... on a warm day.

When we (finally) figured it out, I popped on a new pickup/checkvalve, ran new POLYURETHANE fuel line, and like magic the problem disappeared. It was lucky the engine hadn't been harmed.

As ELT said, you might want to look over your in-tank fuel pickup.
 
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