Os 46 AX. will run when primed then die

by Travis Susee
(Hutchinson, KS)

Os 46 AX. I can cover the carb with my finger and it will prime and then start right up. But as soon as it runs through the prime it dies. I can see the fuel running through the fuel line but it wont fire. It's got a remote needle valve. I have a brand new spare one I'm thinking about replacing it with. Am I on the right track?

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Troubleshootting
by: rcdude07

Before replacing the needle valve, crank it all the way down, then back it out about 2.5 turns (following the instructions for a break in). Also check if the glow plug is good or not.

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os 46 dies
by: beechboy

you may want to check the o-ring on the base of the carb. It may be sucking air.. do you see air bubbles in the fule line when the engine is running the prime?? the needle valve my be leaking air... a small part of fule tubing on the outside may help seal it... also try to run it with a temorary external fuel tank so you can eliminate the tank as a problem.. the fuel line may be pinched or split... is this a new engine? has the engine run good in the past.. are you using muffler pressure?... if the fuel vent may be clogged... good luck

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It might be the low speed needle valve.
by: Anonymous

I had this same problem. I spent hours trying to figure out why it was not drawing enough fuel into the carb to keep the engine running. Then I had a breakthrough. I got the engine running by starting it at a relatively high power setting. This provided enough back pressure through the muffler into the fuel tank to keep the engine running. Then I figured out that it ran great at higher power settings and would not idle correctly. Turns out the low speed needle valve was not set properly and would not allow the engine to run at idle because it was not drawing fuel at idle. That explained why it would idle with the prime fuel and then die after. The higher power settings would provide enough fuel pressure and I never found out because its not normal to start the engine at half throttle or more.

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