I recently refitted a Lucas injection pump to my Polo after a previous owner had fitted a Bosch unit from another VAG diesel that had become faulty.

An added benefit was that the used Lucas pump came with wiring & multi point plug that looked in better nick than the modified gubbins from the Bosch conversion, but I just can't get the engine to fire up.

The main difference in the wiring harness is an extra two-point plug that doesn't have a socket to connect with. Wires are green & brown/white. Brown/white usually denotes earth, but can't identify what the green one's supposed to do. Looks like a diagnostic point but could be a coolant/oil temp sensor, although those terminals are already occupied.

do you not have a haynes manual? Wiring diagrams in there will tell you what the different coloured wires going to the pump are for. I have one at home but wont be there till late on tonight.

do you not have a haynes manual?

Aye - got Haynes manual alright, and tried following the diagram, but they're a bit more complicated than the Bug & Van stuff I'm more used to.

Then, on the other hand - they're not informative enough!

For instance, a unit (#21 in diagram) is labelled as 'Glow Plug Control Unit' and shows 18 connections but not what they do inside the unit.

A splash of colour would help overall too...

Funny how I always find myself in the 'refer to VW dealer / specialist equipment only' zone when I'm trying to find crucial info from manuals!

Most of the other stuff seems logical and mechanical common sense after stripping and rebuilding a few air-cooled engines in my time...

Tried a few other tests today: Injection pump re-primed with fuel, fuel cut-off solenoid works ok, glow plug circuits functioning, injection pump timing altered & re-set (using another identical Polo as template).

Batteries & starter motor healthy - still nothing - not even a hiccup, nor even a whiff off unburnt diesel from the exhaust!

Of course, the used Lucas pump I got off e-bay could be hooky, but it looks in better nick than most I've seen on Polos of that age...

yeah colour wiring diagrams in haynes would be great! But I guess it would mean they'd be significantly more expensive to print sinec now the whole thing is black and white. I can usually figure out what's what using the codes and the table on each diagram which tells you what colour the wires are. Although it may or may not tell you which pins on the pump connector they go to!

Do you know anyone who has access to Autodata who'd print off a couple of pages for you? Might be of help. Failing that find someone local who has the same engine and look at it. Or take some photos in a scrappy.

Appreciate your replies Hayesey, but believe it or not I actually own two identical Polos and have been pretty damn close to ripping my working one apart to get the other one sorted!

I bought Polo #2 from another guy on this forum (Delboy175?) after Polo #1 went lumpy cos of the Bosch pump unit.

Now #2 is a much nicer 1.9DCL than #1 ever was (it's got all 5 gears and a lowering kit!) and it's my daily work run car, but as long as there was a chance of fixing #1 in my spare time,

I would hand it over to my nephew before the mot & tax runs out.

Having come so close after buying another pump and spending many days prepping it, I'm a bit gutted it won't work and might have to strip it all apart again!

Once that happens, it's worth more in bits than the some of its parts so it'll be broken for spares...

Polo 1 (red) & Polo 2 (green)

Edited 4 November, 200817 yr by seamonsta