[T3] Fuel Pump Relay - 69 Fastback

Jim Adney jadney at vwtype3.org
Sun Jul 11 21:18:43 PDT 2021

On 11 Jul 2021 at 15:02, Tim Schiller wrote:

> Without putting a bigger charger on battery, it is at 13V now. There is also
> 13V at the power relay. 

You don't want a bigger charger. Disconnect the charger and let the battery 
rest for an hour or so, then measure the resting voltage. If it's less than 12 V, 
the battery is shot. If it's above 12 V continue charging at the lowest possible 

> Thought I would start at beginning at check pump relay again. There is 13V
> at the 30 pin. When ignition is turned on, there is also 13V at the 85 and
> 86 pins. 

Unless the engine is turning over, 87 will have 12 V on it only for the first ~1 
second after you turn the key ON.

> When I check the 87 pins it is pretty consistent at zero. This is true with
> multiple new relays. If I disconnect pump wire, should I get 13V at the pin?
> I was just trying to eliminate the pump causing a short. 

You can repeat the check above with the red pump wire disconnected. The 
result should be the same. If there was an actual short to ground there, the 
fuse should have blown.

> The negative braided battery cable has some corrosion. I will need to order
> one if I´m to replace. 

That's not a problem, although it's sometimes useful to loosen and retighten 
the connections at both ends of the cable. Any modern replacement you buy 
will be junk compared to the OE one, no matter what the old one looks like.

> Harbor Freight has an ignition bypass to allow starting of car when you
> can´t fully turn key. Is this the type of bypass you are referring to? 

I don't think this is likely to be useful to you here.

> I was reading out of a Clymer manual and it discussed pulling the wire from
> the 85 pin on the pump relay that I believe goes to the ECU #19. It says to
> ground this wire to Bypass ignition. Says the pump should run full time when
> doing this to test if pump is good. Didn´t want to do until asking someone
> much smarter than I. 

The wires to 85 and 86 should be in a white plastic connector, which 
prevents them from being misconnected. Best to just leave them there. If you 
want to run the pump without the relay, just use a small jumper wire to 
connect the 2 red wires on the relay. That bypasses the relay and runs the 
pump full time. If you do this, check carefully for gas leaks and don't forget to 
remove the jumper when you're done.

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

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