[T3] 1970 Fastback FI won't start

William J catnine09 at dslextreme.com
Fri Feb 16 20:07:15 PST 2018

----- Original Message ----- 
From: "Jim Adney" <jadney at vwtype3.org>
To: <type3 at vwtype3.org>
Sent: Friday, February 16, 2018 3:34 PM
Subject: Re: [T3] 1970 Fastback FI won't start

> On 16 Feb 2018 at 10:26, William J wrote:
>>  I've never heard the power relay click . I do hear the fuel pump relay
>> always have.
>>  I wouldn't go by hearing clicks .
> Listening for the 2 clicks, coming ~1 second apart is a really important
> diagnostic tool. If you don't hear both clicks, you know that there's 
> something
> basic wrong with the FI system. It gives you a starting point for
> troubleshooting.
> If you don't hear any clicks, you know that there is either a problem with
> power to the brain or the wiring between the brain and the relays.
> If you hear the first click but not the second, you know that there's 
> either a
> problem IN the brain, or in the wiring to the pump relay, or someone has
> bypassed the pump relay.
> If you do hear both clicks, you know:
> The brain is getting power.
> The brain is telling the fuel pump relay to close and open, so at least 
> part of
> the brain is working.
> If you hear both clicks, but the engine still won't run, you know that you 
> don't
> need to check those things.

 Perhaps one may use the clicks . I can't say for certain if I've ever heard 
the power relay click , I never paid any attention since when you key on 
both relays act at the same time , one powering the ECU and the other 
powering the pump for the 1 or 2 seconds . I hear the pump relay click . The 
power relay even if I key on and then off both should click I just don't 
hear the power relay.

 The reason I said not to go by clicks is the power relay may click if one 
hears it yet it's not an absolute . The relay may click yet the contacts may 
not complete the circuit or the wires to the contacts either side may not be 
secure or clean . If either is the case I still feel it better to  check for 
voltage at the relay.
> -- 
> *******************************
> Jim Adney, jadney at vwtype3.org
> Madison, Wisconsin, USA
> *******************************
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