Starting problems....

Can anyone diagnose a problem from behind a keyboard?

I've gone to start my new dle 120cc today. Plumbing wise it's a straight swap from the 111 that was in there. Only difference is the 120 has an air vent nipple connected to the carb (not sure what I'm supposed to be doing with that)

So, I fuelled up, checked needle settings were as per factory settings and went for a start.
Choke on, ignition on, flipped 3 times and got life.
Choke off, ignition on and flipped. 2nd time fired and ran but then soon stopped. Carb was gushing fuel out. A siphon had started now. I disconnected the fuel line to stop the flow.

Reconnected the line and tried again. This time pinching the fuel feed line to restrict the flow of fuel. Engine started and could be kept at idle as long as I kept the fuel line pinched... On letting go of the line, the engine just cuts out. Again - fuel gushing out of the carb.

Took the carb off and checked for no contaminants... Reattached and this time...can't get fuel to the carb! No flow and no life....

Very confused by it. Can anyone think of anything daft I might be missing (at the risk of looking like a t*t) but I'm frustrated with it.

Could the carb be faulty? I don't think I know enough about it to diagnose it.
May bring it up tomorrow but potentially a non flying day for me...
Cheers all for any advice...
Dave

Dave
Are you sure the needles are seated properly, you could try the carb off the 111,or I have a carbon you can try tomorrow

Dave

i was going to suggest the same as Pete, try the old carb.

My other thought was when you were having syphoning, did you check the internal inlet needle (the little sprung plunger thing inside) was seated properly? The fact that it would not draw fuel after you had it apart suggests you may not have reassembled it correctly??

Bring it with you tomorrow and we can try reassembling in the hut.

Is the Sbach not working either?

Some surfing has led me to a similar conclusion regarding the inlet needle in with the diaphragm. Now that it's gone from too much fuel to none at all.

I'll try getting it off again and try and ensure its seated properly and not bent.

Photos isn't of mine but just confirming this is the part we're talking about.

Why does my new carb have an air vent nipple on it whereas the 111's didn't? Can I still interchange them even with this difference?

Ta

Oh and with the noise coming from the dla..... I don't want to risk more than a bearing replacement so the sbach is currently out of action.

Leaves me with agacia and one pack only...looks a bit windy tomorrow so not w lightweight 6c day.

DaveBright wrote: Some surfing has led me to a similar conclusion regarding the inlet needle in with the diaphragm. Now that it's gone from too much fuel to none at all.

I'll try getting it off again and try and ensure its seated properly and not bent.

Photos isn't of mine but just confirming this is the part we're talking about.

Why does my new carb have an air vent nipple on it whereas the 111's didn't? Can I still interchange them even with this difference?

Ta

Yes that's the inlet needle, can't think how else fuel would be able to syphon through, but I'm no carb expert!

If the 111 carb fits, I would go with that, dont think the vent nipple should make much difference.

When you reassembled the regulator cover - Did you ensure the groove on the silver spigot was slid into the fork on the valve operating arm.? if it was not, that would depress the regulator more (simulating very high atmospheric pressure and significantly increase fuel flow pressure ) Come to think of it, it may have assembled like that in the factory and that may be the cause of fuel apparently syphoning.

The nipple on the back of the regulator plate would be used to pipe into the fuselage to provide a more balanced atmospheric pressure on the regulator.

suggest you download this manual
www.walbro.com/media/21936/SERVICEMANUAL.pdf

kevinross wrote: When you reassembled the regulator cover - Did you ensure the groove on the silver spigot was slid into the fork on the valve operating arm.?

I did look at this carefully when reassembling but no, the parts you state don't locate together. I did think that Logically they should as they looked like they belong together..... Maybe it's bent? I shall have another look in morning as I'm now home and the model as you know is not. It does however seem solvable either by careful realignment of the bits in the new carb or putting the old one on so this encourages me to bring it all tomorrow and, assuming I can get it to run, I can at least get some breaking in flights done.

Thanks for the link to the carb pdf....

Thanks for your suggestions chaps.

Dave

If the little spiggot on the diaphram isn't located in the fork on the rocker, no wonder it isn't running, that opens and closes the needle. Hopefully we can sort it tomorrow.

Thanks to all of you for your suggestions on here, help at the field yesterday including Frank. The issue was as thought, the diaphragm spigot was not engaging the 'fork' - manufacturing fault.

Swapped the carb over with my old one from the 111 and she burst into life.

Cheers all