Help with 74 400 can't stay running

Deleted User · Post by **Deleted User** » Sat Dec 22, 2007 8:27 pm

Hi, all!

Just registered here. I have a 74 400 model sled. Kohler 339cc i believe
It has a walbro wdb 31 carb. I aquired this non running

I just rebuilt the carb, and set the low and high speed adjustments according to the tuning section on jdsleds

I put the carb on the motor and it fired, ran, idled fine for about 15 minutes.
Then I revved the motor a bit and it died.

Since then, I can only run it with the choke closed 90% and have to crack the throttle every few seconds to stay running. I cant run with the choke open even at open throttle- it bogs like it has no fuel and dies

I think the fuel is not making it from the crankcase to the combustion chamber or somthing. When it dies, the plugs are dry. Maybe not making it out of the carb?

The pump in the carb is pulling gas and also returning some to the tank.

I just can't get it to stay running. I don't think the crank seals are leaking, at least not enough to let the motor die. Maybe too much fuel is getting sent back to the tank?

Can anyone please help with some input? I am not sure if this is a reed type motor either.

400brian · Post by **400brian** » Sat Dec 22, 2007 9:20 pm

What is the condition of your fuel tank? Fuel filter? Everything MUST be clean, no fuel residue, no rust.

Have you looked at the pick up in the tank?

Have you read the "How to get your sled running" FAQ?

Did you check / adjust the metering lever in the carb?

BTW, you should have a CCW/Kioritz engine.

Deleted User · Post by **Deleted User** » Sat Dec 22, 2007 9:44 pm

Thanks for the quick reply.

I am using a small gas can at 50:1 mixture with a clear small engin fuel filter.

I did read the getting your sled running section. I am trying to absorb as much info as I can on this subject.

As far as the metering lever.

I assume by adjusting it you would have to bend it? Your talking about the lever that holds the needle against the seat with the spring pressure- Right?

I did not mess with that. A new one came in the carb kit, but I reused my old one. they were identical in shape.

It definately seems to be a problem only with the idle circuit . I can hold the rpm up sort of and keep it running.

400brian · Post by **400brian** » Sun Dec 23, 2007 4:15 am

Will it run if you open the idle mixture screw futher?

If it ran for a while, it makes me think smothing changed. Sure sounds like isn't getting enough fuel. Wonder if it pulled something into the idle circuit?

Otherwise it sounds like the metering lever isn't leting the needle open.
Do you have the spec?

Deleted User · Post by **Deleted User** » Sun Dec 23, 2007 1:02 pm

No, the motor will not run if I open the low speed screw any more. I started out at 1 3/4 turns and have tried adjusting it in and out plenty of times.

It definately seems like somthing must have changed. I disassembled the carb last night to check. It was as clean as can be. I stuck a needle through every small hole I could.

I am not sure which spec you are asking about. I don't have any info on this exact carb. I need to get a shop amnual still.

When I did the "rebuild" , I replaced every part that came in the kit as far as gaskets, fuel pump portion, meterting portion (gasket with metal disc I believe)

The only thing I can think of that doesn't seem 100% is one the three small springs that sit in those recessed circles and press on the clear flaps. One spring is stretched out because I pulled on it and it was stuck when first disassembling the carb. New ones did not come in the kit.

The temperature dropped alot since yesterday, so I don't think I am gonna get to looking at it today.

Thanks

400brian · Post by **400brian** » Mon Dec 24, 2007 3:58 am

Jeremy, email me at: ca-2@centurytel.net
I'll send you the page out of the manual.

flacker36 · Post by **flacker36** » Thu Jan 03, 2008 11:31 pm

Jeremy - Did you figure out what was the problem with your sled. I am having the same problem & I many others haven't figured it out yet.

Joe

toolmantim · Post by **toolmantim** » Sat Jan 31, 2009 2:16 am

I also have about the same problem except I have to leave the choke on to get it to rev up to move. And I don't have those three small springs in mine, do I need them? What are they for?
My sled is a 72 400