URGENT!!! Fuel pump/spark shut-off.

[stiglet]

Hi.

Just finished swapping a 7A engine and wiring loom into what was originally a 10v KV Coupe. Got the ignition wired up and..... nothing. The fuel pump will not work, and i'm pretty sure there is no spark.

Got the dash wired up, and the moment i turn the ignition on there is a brake warning on the check system. Circle with exclamation mark in middle, flashing in red (this is the same warning you get when you pump the brakes to test the bomb).

I've heard that the ecu will shut off the spark and fuel if it detects a serious problem with the brakes, and will not let you start the car. Could this be it?

Fuel pump is fine as it worked fine with the old engine, and the new 7A engine and ecu is also fine.

URGENT HELP NEEDED AS I NEED THE CAR RUNNING BY MONDAY!!!!!

Cheers.

[S2central.net]

There's nothing I have seen or heard of to backup the rumour you heard about brake alarms or any other autocheck thing that prevents the engine from starting.

I suggest there is something subtly wrong in the wiring conversion that is keeping the fuel pump off - I've had a KV engined B2 Coupe and a 7A engined B3 Coupe in the past - my memory is the fuel pump wiring is very different.

Cos the KV runs good ol' K-Jetronic, I recall it had some sort of trigger signal that only activates the pump relay when the engine is running... Whereas on the 7A there is perhaps a different trigger signal and/or relay actually.

If you are really stuck I can go in search of schematics but I may not have exactly what you need to resolve this.

Paul

[anton]

I think the signal to activate the fuel pump comes from the ecu, which activates a fuel pump relay.

Any ideas where this relay is?? it's not labelled on the fuse box cover. I'm thinking the relay is absent on the 10v, so i just need to plug it in somewhere...


This is Alex logged on to Anton's account btw

[S2central.net]

Well the Haynes manual (1491) has some 7A schematics - I don't have proper official ones yet...

The 7A ECU does indeed trigger the fuel pump relay (J17) which is wired into position 10 on the main relay board. This same relay also switches the feed on for the lambda probe heater (Z19), the ISV (N71) and EVAP (N80) via Fuse 28.

The 7A ECU should connect from terminal 7A (yes thats 7A according to Haynes) on a red/blue wire to pin 47 on the pump relay.

The switched output from relay on pin 87 goes thru fuse 13 (15Amp) and onto the fuel pump (G6) via a green/yellow wire.

I can't scan or copy here, but I could draw this up real quick if it helps

[S2central.net]

Right I think I have nailed it... My memory aint so bad.

Just found my really old and oily Haynes manual from my ownership of the KV engined B2 Coupe (HAynes 605).

The fuel pump relay and wiring is different on the KV engine. You need the correct relay and intimate knowledge of the fusebox numbering system to work this one thru, but essentially the KV system uses a relay that is triggered by the TCI module (ignition pack) which doesn't exist on the 7A.

Fortunately the KV uses different pins on the fusebox than the 7A... Ahh this is crazy - I need to draw it to explain properly.

[S2central.net]

In the meantime - do this -

1. Remove the fuel pump relay from position #10 (ten)

2. make up a sturdy bridge connection with 2.5sqmm wire - just long enough with spade connectors to place between terminals 30 and 87 and 87a - that should turn the fuel pump on (all the time) so you can crank it

Paul

[stiglet]

Thanks very much!!

I was mulling this over last night and came to the same conclusion, unfortunately can't get to the car until later today so will let you know.

Cheers.

[S2central.net]

Schematics coming real soon

[S2central.net]

Here we go then...

Pretty obvious but I've annotated the important stuff. You will need the correct fuel pump relay though - the one used on KV is not gonna work on the 7A as you will see from the schematics.

Have you wired the 7A loom all the way up to the main fusebox already ?
You need that 'BS' pin to trigger the relay.

Good luck,

Paul

PS - Really glad I kept these old Haynes books now

[Mikes2]

you have changed over the flywheel etc as well I assume.

[stiglet]

Still at work so haven't had a look yet.

Yes i've wired up to the fuse box, but haven't touched any relays. I have a complete 7A donor car so i'm guessing just swap over relays?

MikeS2: See seperate thread about aluminium flywheel

Have changed G/B too.

Cheers

[stiglet]

Brilliant!!! those schematics are perfect, should be able to get the ****** running now.

Where do you get all your info if you don't mind me asking? Or is that a trade secret??

[S2central.net]

I have amassed lots of technical info over the years shall we say - most of it on paper in terms of the electrical info which often needs a bit of translation or simplification for others less experienced in the foibles of wiring up an Audi. I have old Haynes manuals, some Bentley books and heaps of stuff from Erwin.

With the right relay fitted you'll be running as long as the wiring to the fusebox is correct. Glad to be of assistance sometimes - even if its not strictly an S2 issue here.

I'll add a 3B and ABY/ADU version of those fuel pump areas as they may be useful for others in the future doing S2/RS2 conversions from a KV or 7A engined quattro.

Paul

[stiglet]

Glad to be of assistance sometimes - even if its not strictly an S2 issue here.

..... yet!

[anton]

right, well as stiglet is slacking with some presentation or something i have got the relays swapped and the pump now works! woo! do feel a bit stupid for not checking that but to be fair the relay decriptions on the cover are useless lol. next problem however is that the starter motor wont stay on....as in it will only turn 2-10 revolutions before the solenoid de-activates and the cog comes off the flywheel so i cant try and start the damn thing! the power cable is good and the blade conection wire is connected and dissapears into the engine loom rly dont have any ideas with this one, any clues?

cheers

Ant