Engine pops a lot, and cuts out when slowing down

[noshell]

First off i want to say a big thanks for all the help over the past few weeks. Its been a lot of fun for me.
So, my current small engine is very difficult to throttle down.
It can idle very low and has loads of power at full throttle (for one of these)

Even the slightest reduction in fuel causes it to pop rapidly and often cut out. It is very difficult to get back down to idle after full power.


Now i suspect this is down to my crude fuel injector which is a short length of pipe with some 1.5mm diameter holes in it.

Can anyone shed some light on this?

[wannabebuilderuk]

Sounds like you're throttling down the fuel too fast and chamber pressure is higher than fuel pressure so it puts the flame out, try doing it slower.

Is your nozzle holes pointing to the sides the of flametube or straight down towards the end?

[noshell]

I am throttling down very very slowly.

The holes point outwards towards the walls of the flame tube, and are about 1-2 inches in from the end of the flame tube(the capped end)

[noshell]

Actually your theory sounds quite possible as im using butane which is low pressure.
Edit. Im going to stick a flow tube ln the fuel line and see what it does

[racket]

Yep , you need a pressure gauge on the fuel supply , with the pickup from near the injector .

Try warming your butane cylinder by sitting it in a bath of warm water , this will help maintain your cylinders vapour pressure .