Tachymetric relay

[SootySport 23]

Is this it? Mounted on the metal plate in centre of the photo.

Im looking for 12v thats supposed to feed the fuel pump, not getting 12v at fuse 14.  Chassis -ve connection ok at fuel pump.  Haynes diagram shows wire 76 going direct from fuse14 to tachymrtric relay, I hope that’s right.

[DamirGTI 342]

No , that's the ignition amp/module .

 

Tachy relay will be under the dash near the steering column or ECU .

 

 

D

[SootySport 23]

That answers my problem I think, thought the fuel pump comes on with just the ignition key turned on.  I’ll give it another go and crank it up. Thanks for the info Damir.

[petert 588]

Position varies with year/model. On very early models say <87, it’s in a black box on the chassis rail near the gearbox. Motronic DKZ models, don’t have one at all. Just a normal relay, controlled by the ecu, in the driver’s footwell (RHD).

[SootySport 23]

Mines a jetronic jan 1991 so should be in the lower dash.   Going to spin it up in the morning and see if 12v comes through it.

[petert 588]

Just follow the green wire.

[SootySport 23]

The relay works ok on cranking, spark plugs firing ok and 12v at the pump but pump not working. it was working on the bench when I cleaned it up, must of disturbed something when re-fitting it in the tank so it will have to come out again.   It reads 2 ohms across the terminals, do you think that’s too much of a short or about right?

[SootySport 23]

Well , the pump is cream crackered, double checked it out of the car and wired direct to a battery.   Going to have a go stripping it down and changing the pump itself. 
Do I need the 3 bar pump for the 1.6gti ? there’s so many versions out there and I’m not sure what pressure I need. 

[welshpug 1,661]

pumps are not rated by pressure but flow, the pressure is set by the presaure regulator on the fuel rail.

 

only two types of pump for a 205 gti, early black housing with a fly lead, and phase2 white housing where the plug is part of the top.

Edited July 2, 2020 by welshpug

[SootySport 23]

So is 3 bar enough? This is the one I have but looks to have been changed in the past as different wire connectors have been Crafted on the loom.

[DamirGTI 342]

Before definite write off  .. try to connect it on a 12v and hit/tap it with a rubber hammer , or tap it against the table wile connected on a 12v .. if you get lucky it might free off ..

 

Rollers on the bottom of the pump often stuck thus the pump stops spinning .. only ever so sightly thin film of fuel varnish on the roller cell mechanism and it locks/binds up . 

 

That's if the brushes and commutator are still good ..

 

D

 

[welshpug 1,661]

wiring looks original but the top of the pump has been messed with.

[SootySport 23]

Top of the pump is a moulded piece of PVC so can’t have been messed with.  I’ve tapped The pump many times on all sides and it just turns very slowly so well gummed up. 
Taken the pump assembly apart now and the part number is Bosch 0 580 464 993, might help others if they need to order one, there is a few available on EBay @ £86 ‘ish, I have ordered mine.

[welshpug 1,661]

definitely messed with, it should look like this with potted wires and a fly lead.

Edited July 3, 2020 by welshpug

[Philpooma 30]

On 6/30/2020 at 7:52 PM, DamirGTI said:

 

Just following on from this Damir, I was testing my fuel pump the other day, with the ignition turned on, does the pump not prime the fuel rail then? 
With the ignition on, I was getting no power at the pump, but is it that the engine needs to be turning over (300rpm) before the pump primes?

I have 13.5v going into the tachy relay, but nothing coming out.

 

Edited July 4, 2020 by Philpooma

[Philpooma 30]

2 hours ago, Philpooma said:

 

Hi have just properly read your article on the Tachy relay Damir and I understand now that it wont feed power to the fuel pump unless the engine is being turned over by the starter motor.

[SootySport 23]

14 hours ago, welshpug said:

definitely messed with, it should look like this with potted wires and a fly lead.

See what you mean now, although it’s just an uneccessary extra connection. My loom goes straight onto to the spade terminals.