Fuel Not filling the Carb bowl?

Im currently working on an Tomos A3 kitted with the 70cc kit.

(Mikuni Vm20) I cleaned out the carb due to stuff in the tank. I put the carb all together but still wont start. If I spray carb cleaner in the air way it starts strong then dies... SO! I know that the problem is that its not getting fuel. I opened up the bowl and it was empty, once I opened it up it started to fill. what causes this?

Re: Fuel Not filling the Carb bowl?

It could be a few things....float/needle stuck...gastank not venting...petcock clogged or not working

Re: Fuel Not filling the Carb bowl?

Brent Bublitz /

Your float is not adjusted properly and is being jammed up so the needle is sealing the fuel flow. You need to get it so the float is level when the carb is upside down, and the needle opens and closes fine when right side up.

Re: Fuel Not filling the Carb bowl?

Alright, I checked the Float needle and the float. its level when its upside down, and set well. There is some resistance when it pushes the needle up. The needle almost drops out when the bowl is empty. I put it back on and no fuel is still coming. Any tips?

Re: Fuel Not filling the Carb bowl?

Take the carb off and remove the float bowl

Hook the fuel pipe back up to the carb.

Turn on the petcock

You should get fuel dribble out of the float needle orifice.

If no fuel, try reserve setting on the petcock

If still no fuel the petcock screens are probably sealed over with crud.

Re: Fuel Not filling the Carb bowl?

Brent Bublitz /

There should be no resistance on moving that needle at all. Sounds like something is binding.

Re: Fuel Not filling the Carb bowl?

Brent Bublitz Wrote:

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> There should be no resistance on moving that

> needle at all. Sounds like something is binding.

I second this, there is only so much that goes into allowing fuel to enter the bowl. Use compressed air if you have it to blow that crap out along with carb cleaner. If fuel is coming out of your fuel line with out it hooked to the carb then it is in your carb if it is not coming out then follow it up. there is not to much that goes on with fuel flow all the answers are in this post start from petcock and work your way down. and don't forget about the gas cap vent like Bobby said. Have you taken the needle valve out to see if their is something blocking the flow?

What does your gas tank look like? rusty? or clean? Have you cleaned your tank since you said their was stuff in your tank? not just drain the old fuel but clean? Another tip is to hook up a external fuel source to a known clean tank or what ever you can put together and see if that solves the problem.

Remember it is a elimination process so work from the top to the bottom since that is the way fuel flows. (edited)

Re: Fuel Not filling the Carb bowl?

Everything looks okay. petcock good, Fuel flowing correctly. I double checked and got it running late last night. The bowl filled and started on the second kick. This morning i spent 20 min kicking before I headed off to work. Sounded like it wants to start. I made sure that Everything was tight and there were no Air leaks and cleared out the Jets. Still nothing.

Ive narrowed down my problem to the jets? they're clean and free. Why wont it work? Im lost.

Re: Fuel Not filling the Carb bowl?

best test i know is remove the carb, blow in the fuel inlet, flip the carb a few times.

upside down, no flow, right side up, no resistance, repeat.

just pulling the bowl off you can be changing something blocking flow.

interesting it drained the bowl overnight, that sounds like flooding rather then starvation.

depending how you're cutting the ped off, petcock / kill switch.

shot of carb cleaner > 20 min of kicking.

Re: Fuel Not filling the Carb bowl?

On a lawn mower or car, I'd be tellin' you that the bowl vent is plugged,but I don't think moped carbs are so tight that they need a vent,really. It sure sounds like a venting problem though. don-ohio

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