I have a ZDZ80 in my Ziroli Hellcat. It has always run well, but now its' giving me problems. When i throttle up i stops. It does not matter where i set the low needle valve. I have tried all the way from 3/4 of A turn to 2 turns. I cleaned the filter, and tried fresh gas but rarely can i get it to full throttle. Any ideas?
Thanks.

This may sound silly but I have seen it happen. Make sure the sensor is connected properly. If it is, try a replacement ignition module. Dan.

Nothing is a silly suggestion at this point. It is the original Falkon ignition so maybe it is pooched. I'll see if i can try a different ignition. Anything else to check?

Have you tried to open the high needle? I would open it 3 to 4 turns to make sure fuel is flowing. When does the engine quit? During acceleration or after full speed is achieved?

The engine runs nicely at full throttle. When i am setting it up i set the high end first. The problem is when i throttle down and then try to throttle back up...it stops then irregardless of low needle setting. I checked the plug this morning and it has a nice, dark tanned colour (not too rich, not too lean).

Well if it's got a Falkon ignition it's pretty old. Usually those things either work or they don't. Suggest eliminating the the switch or whatever is between the ignition battery and the ignition as a troubleshooting technique. Now I'm stretching the old memory but IIRC the plate on the back of the crankshaft that makes the rotary valve intake work, can get loose and mess up the intake timing.

You may want to try contacting AMR for assistance, they are the Canadian importer/distributor for ZDZ.

After two other rebuilt carbs and an RCecell ignition, now wont even start. I have traced it back to the fact that the engine is not drawing fuel. Wonder what could stop the carb/engine from drawing fuel?

Make sure the pulse line/hole is making a proper connection to the carb. Sometimes the gasket
will block the hole if it is not aligned properly.

I've made sure the holes line up and are clear. Could the engine itself not be sending a pressure signal?

Check insulator block between carb and engine for cracks,if it has the phenolic type