Help identify Pierburg carb

Hi,

I've a 1987 mk 1 cab with a Pierburg 2e carb that needs to be repaired. It starts but will not idle.

We have the service instruction diagram but there are inconsistencies (see photos). Is this because the manufacturer made later modifications that are not reflected in this diagram? Can anyone help me identify the right diagram or explain why the diagram doesn't match?

Photos attached, many thanks 🙂

I haven't spotted any differences so far. What specifically have you noticed that is different?

For a specific example, in the picture there is only one vacuum pipe coming out of the choke plate but mine has got two. I've circled the bits I mean 🙂

On that specific difference, it looks like for the purpose of the diagram, the extra vacuum hoses are not considered part of the carb, so one of the ports is shown without a hose attached. It looks as though someone has switched round the inlet and outlet hoses on the choke pulldown unit. I don't know whether swapping them over has any effect, but it would seem worthwhile to swap them back anyway. There is a diagram of the complete vacuum hose layout at the end of the manual which would be worth checking against your carb.

Ah right, I'll take a look. Thank you.

I have one more question if you can help: the accelerator cable cannot be adjusted to change idle speed as when you pull on it, there's nothing to keep it in place. I've put cable tie on to hold it in place as temporary fix but what can I do to hold it permanently?

I've put the cable tie where the arrow is pointing in the pic below

It looks like the accelerator cable is at the limit of its adjustement, so something is wrong. It is worth checking the cable attachment at the accelerator pedal as it hooks into the centre of a massive rubber bush which is known to perish, so there could be a fair amount of slack at that end. However, there should always be some free play in the cable at idle, so you shouldn't be using it to adjust the idle speed.

The idle speed is controlled by the hexagon headed screw on the back of the throttle plate actuator (commonly known as the 3-point unit). You can adjust it with a (possibly 13mm?) spanner by reaching through the gap between the bulkhead and the carb.