HELP. 2006 Octavia mk2 1.9 tdi. Lift pump in fuel tank not working.

What seemed like a slight misfire and shortly after that engine stopped.

Will turn over on starter but will not fire.

Removed pump.

Cleaned and tested, it works on the bench.

Checked all fuses, they are fine.

Checked all relays, they are fine.

I don't know where to look next.

Any help would be greatly appreciated.

How many miles on car?

187,000

Did you try measuring for volts on pump connector when turning key to ignition on or cranking position?

Could be just that the pump motor brushes have worn so much that there isn't enough contact to start the motor when there's load on the shaft?

No supply to pump. Tested at connector that connects to the pump.

Tested pump on bench in tub of diesel. It worked fine.

Good info, that suggests electrical fault then, clearly.

Please supply VIN or reg so I can look at most appropriate wiring info for you.

SM06HPN

OK, so not too much to check. Fuel pump relay is in position D4.1 of this relay holder:

Circuit looks like this, with two fuses to check in different locations. Apologies for the clunky edit on #27!

G6 is the fuel pump itself, 12V in on the blue/red wire, earth on the brown.

I'll check the fuses again and let you know.

The relay holder does not look familiar.

Where is it located?

I thought I had found and tested all the relays.

That relay holder is rather inexactly described as being "Additional relay holder below dash panel".

I see. I was under there this morning. All the relays tested ok. I'll recheck the fuses.

The 5 amp one in the engine bay also goes to the glow plug control unit, so you'd probably have seen a warning light if that had blown, the cabin one appears to be just for the fuel pump though.

When you say the relays work, you mean you can hear them click? That doesn't say anything about the condition of the current-carrying (or not!) contacts.

I am an idiot. You are brilliant and I am an idiot.

Rechecked the fuses and I messed up with #27. The card on the back of the panel is mirror image of fuse board and I have been counting wrong.

15A fuse in correct slot and it runs.

Been running for about 15 minutes so that should be ok now.

A fresh pair of eyes makes all the difference sometimes.

As I have your attention the air bag light is on and despite trying two different diagnostic testers no fault codes are coming up.

Any ideas?

13 minutes ago, RalphEBurton said:

As I have your attention the air bag light is on and despite trying two different diagnostic testers no fault codes are coming up.

Any ideas?

Not sure; VCDS would be handy if you can find someone nearby with it.

I'll have to have a look.

Thanks for all your help.