Re: [T3] 1973 T3 Fuel Injection Relay Problem

["Jim Adney" <jadney@vwtype3.org>]

On 8 May 2001, at 21:47, Peter Legault wrote:

> I have a 1973 TypeIII FI automatic. I have recently had a shut down in
> fuel supply. I hae the "How to keep your VW alie book and found that
> the power wasen't going thru the relay. I hae since replaced the fuel
> pump relay with no results. For now I have directly hook up the pump
> to the an inginition terminal on the fuse block. This is working
> although I am by-passing the reay alltogether. 

The relay is part of an important safety system which allows the 
brain to shut off the fuel pump if the engine should stop for any 
reason, as in an accident when you or your passengers might be 
unconscious. It's important to get this fixed.

The normal fuel pump power is fed thru a fuse which may be blown 
now due to the short. Do not leave this feed connected to the 
ignition switch or you may be replacing the switch soon, and that 
is troublesome and expensive.

> I had hooked up power to terminal 30/51 first assuming that no
> power was getting to the coil of the relay. This did work but there
> is another wire hooked up to terminal 87 (fuel pump supply voltage)
> it is not shown on the diagram "System Diagram of Electronic Fuel
> Injection" in the book. 

I think the power to the coil comes from the fuse box, but I can't 
remember for sure. The other side of the pump relay coil goes to 
the brain which connects it to ground when everything is running 
properly.

> Shortly after starting the car I noticed this wire was shorted
> hence the insulation was melting. Where does this wire go to? I have
> disconected it for now and the engine runs fine. 

The second output wire goes to the electrically heated aux air 
regulator which is used on 70-3 AT type 3s. Look for that wire just 
to the right of your distributor and see if it is shorted to ground 
somewhere near there. Once that wire has melted it could be 
shorted to ANYTHING, so it will be necessary to proceed with 
caution with it now.

-
Jim Adney
jadney@vwtype3.org
Madison, WI 53711-3054
USA

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