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2.6i not priming the fuel pump to start - Printable Version

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2.6i not priming the fuel pump to start - silverbullet - 01-30-2017 02:44 PM

Hi everyone, long time no visit!

The 1995 2.6i has been doing sterling service here in the UK, so nothing to report but... I serviced the fuel filter at the weekend and whilst it definitely runs better, it seems to be very difficult to start first thing, with lots of cranking required before it splutters into life.

This bus has never primed the fuel system when switching on the ignition to position 2; I have a full set of wiring diagrams to hand (early Motronic system), but cannot work out why the pump only runs when cranking or running Undecided

The alarm/immobilizer has never worked (unplugged) so should I go looking there first? All the relays are present and correct.

Hardly anyone in the UK seems to know their way around a T3ZA so I am grateful for any advice!

Ian


RE: 2.6i not priming the fuel pump to start - Oberon - 01-30-2017 04:47 PM

(01-30-2017 02:44 PM)silverbullet Wrote:  Hi everyone, long time no visit!

The 1995 2.6i has been doing sterling service here in the UK, so nothing to report but... I serviced the fuel filter at the weekend and whilst it definitely runs better, it seems to be very difficult to start first thing, with lots of cranking required before it splutters into life.

This bus has never primed the fuel system when switching on the ignition to position 2; I have a full set of wiring diagrams to hand (early Motronic system), but cannot work out why the pump only runs when cranking or running Undecided

The alarm/immobilizer has never worked (unplugged) so should I go looking there first? All the relays are present and correct.

Hardly anyone in the UK seems to know their way around a T3ZA so I am grateful for any advice!

Ian

(01-30-2017 02:44 PM)silverbullet Wrote:  Hi everyone, long time no visit!

The 1995 2.6i has been doing sterling service here in the UK, so nothing to report but... I serviced the fuel filter at the weekend and whilst it definitely runs better, it seems to be very difficult to start first thing, with lots of cranking required before it splutters into life.

This bus has never primed the fuel system when switching on the ignition to position 2; I have a full set of wiring diagrams to hand (early Motronic system), but cannot work out why the pump only runs when cranking or running Undecided

The alarm/immobilizer has never worked (unplugged) so should I go looking there first? All the relays are present and correct.

Hardly anyone in the UK seems to know their way around a T3ZA so I am grateful for any advice!

Ian

Hi Ian
As you correctly note the fuel pump should prime the system for a couple of seconds when the ignition switch is turned to pos 2. That's done by a relay in the cluster behind the right tail light assembly and if you turn the key to pos 2 whilst standing outside the driver's door you should clearly hear that happen. That compartment is a very restricted space in which to work, but it's not too difficult to remove the relays to test on the bench or substitute. (I think there are 3 relays there, one is for the a/c, one is the fuel pump prime and the other the fuel pump main. Somebody correct me here please)

My prime relay works normally but my 2.5 bus still takes 2-3 seconds of cranking to fire up.

Cheers
Colin


RE: 2.6i not priming the fuel pump to start - silverbullet - 01-30-2017 06:33 PM

I have had some advice via Facebook, think the fuel pump may be on the way out, but I am having trouble identifying the particular one used on the 2.6i

Seems to have a Polo terminal adaptor (Packard plug iirc) fitted to a WBX efi-type pump, but with a screw-on nylon outlet pipe going to the filter.

Can anyone provide me with a generic Bosch part number for the pump?

22S part numbers are a stonewall here Confused

Thanks, Ian


RE: 2.6i not priming the fuel pump to start - syncromad - 01-30-2017 07:31 PM

just fit a Golf or Audi Fi pump, few piping wiring mods and it will work


RE: 2.6i not priming the fuel pump to start - Gerard W - 01-31-2017 07:35 AM

Fitted a Bosch 1800 Golf pump to my 2.6i. No mods, just a plug in. Did the job myself in the veld.


RE: 2.6i not priming the fuel pump to start - silverbullet - 02-02-2017 03:46 PM

Thanks all, but I would rather do it right if I can, oddly the bus sterted first crank this morning after standing for two days Undecided

Back to the original question: Should the early 2.6i ...404B ecu etc prime the fuel rail when the ignition is switched on, or not?

Trying to work out if I have a pump or wiring/relay fault.