[T3] [Non-DoD Source] Re: 1970 Fastback FI won't start

Jim Adney jadney at vwtype3.org
Thu Feb 15 06:45:01 PST 2018

On 15 Feb 2018 at 14:29, Dorough, Don CIV, NPPSC N3/PSD Pensacola 

> Good news, I found my problem.  At one point I had swapped out the
> battery and there is a heavy red wire that connects to the positive
> battery lug.  That wire was lose. When I tightened the positive
> battery lug TIGHT, that red wire made good contact and the engine came
> to life!  

Good, that was an easy fix.

> Now, one thing you said concerns me.  When I turn my key to the on
> position, I hear my fuel pump energize and it never stops running. 
> Something is wired wrong in the fuel pump/double relay circuit.  This
> would not be a problem with the engine running, but I understand that
> this is a built in safety feature that is designed to cut off the fuel
> supply in the event of an accident or the engine dies, etc.  

The most likely cause is that there's a FI wire going to the starter solenoid 
that's connected to the wrong terminal there. It MUST go to a terminal that is 
hot ONLY when the starter is running. That will be the terminal that the wire 
from the ign switch connects to. The original FI starters had an extra lug for 
this purpose, but if the starter has been replaced, you may need a splitter to 
get it wired correctly.

If the FI wire is connected to a terminal that is hot ALL the time, the pump 
will run as long as the key is ON, AND the FI will run rich. It's sort of a 
"choke" for starting.

> Do you have a wiring diagram of just the relays/fuel pump circuit? 

It's all in the Bentley manual, but it's not explained in depth.

Jim Adney, jadney at vwtype3.org
Madison, Wisconsin, USA

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