Erratic Tick-over - 280i

[v8s4me]

I'm still struggling to get an even tick-over.

If I pull the vacuum pipe off the (correct) outlet on the WRU (thanks Andy) and block off the vacuum pipe the tick-over settles down nicely. If I then connect a separate tube to the WRU and create a vacuum the tick-over oscillates up and down again.

What's going on here?

Also, I can't seem to get a 3mm Allen key to engage in the mixture screw. Is there a nack to this? Could it be something larger than 3mm?

[Grady]

Should be 3mm. Stupid Q but is the wrench long enough to engage the adjustment screw? IIRC, it is about a 3" down-tube to the screw.

[v8s4me]

90mm, how's that?

[v8s4me]

It's definitely 3mm. I've dismantled a spare unit and this is what it looks like inside...



The roller actuates the valve in this picture...



So presumable this is the valve which controls the fuel flow to the distribution head.