casem

I just snagged a nice '86 4kcsq off craigslist for $350, but it's been sitting for 5 years so it's got plenty of issues.

Recap to the day I bought it- I was trying to start the car with my jumper box but the battery was too far gone to make it turn over- BUT the fuel pump WAS running, it was loud and buzzy.
Yesterday I put in a new battery and the car turns over fine but now the fuel pump doesn't come on.

Here's what I've done so far to troubleshoot:
I have swapped out the fuel pump relay with 3 others, even used a jumper wire where the relay goes, but the fuel pump doesn't do a thing. It's also notable that fuse #13 (fuel injection, etc) doesn't get power to it.
I used my test light on the wires on the fuel pump and neither of them have power to them.
Also, it was completely out of fuel before I started working on it, now it has a few gallons of fresh fuel.

Any ideas?? Different way to test the fuel pump? I'm stumped...

club racer

An easy thing to do would be to put your jumper wire in the relay and check for power to the fuel pump connection under the back seat if you have power at that connection and it still does not run then try hooking your battery jumper directly to that connection or the fuel pump itself ,if it still does not run try tapping on the fuel pump to see if it will break loose internally .

Blewtoon

My urq is getting no power to the relay. or the inst. cluster & also no spark.

casem

Tried all of that, and I'm still not getting power to the green wire that runs to the fuel pump at the connection under the back seat or at the fuel pump itself. Even when I used a jumper wire at the fuel pump relay.

casem

but my inst cluster works and I have spark.

Katman

So to be clear:

You have jumpered across the two 'large' terminals where the fuel pump relay is, and you STILL are not getting power at the power wire to the pump, at the fuel pump connector under the rear seat?




As far as I can see, there is only fuse 13 between the relay and the connector.

With fuse 13 in, do you get power on BOTH sides of the fuse? (Fuse has TINY openings on the top, so you can get at both sides of the part that blows to take a voltage reading)

Also, try checking for power on the two pin connector to the O2 sensor. They power the o2 sensor heater, and should be powered whenever the fuel pump gets power.

If that checks out, maybe one of the connectors underneath the fusebox has come loose or become disconnected?

From Huw's diagram: It looks like the O2 sensor heater is powered by black connector B on the back of the fusebox, and fuel pump is powered through black connector H..

(Are any of the other things on the same connector H not working, like maybe the tailights?)



Huw's Audi Fusebox Diagram:
<img src="http://www.humanspeakers.com/audi/images/fusebox.gif">

GOod luck!<ul><li><a href="http://www.humanspeakers.com/cgi-bin/audi_img.pl?image=images/fusebox.gif&amp;desc=This%20is%20the%20internal%20 schematic%20of%20a%20typical%20late%201980's%20Aud i%20fusebox">Huw's fusebox diagram..</a></li></ul>

casem

The diagram was much needed.
Unfortunately though, I'm still not getting power.
Connector H IS plugged in good. I did jumper the fuel pump relay using the two BIG slots. Everything else on connector H works.

As for fuse #13, I'm not getting power to it either. I've pretty much traced the green/yellow wire for the fuel pump all the way from the fuse block to the pump itself and it looks fine.

Haven't bothered with the O2 sensor connector yet though.

Katman

Hmm.. If youhave no power at fuse 13, and jumpered the relay correctly, then you must have a prooblem internal to the fuse block.

You could try jumpering power directly to the terminals of fuse 13 (bypassing some of the fuse panel), and see if that powers up the pump. If the pump then works, could confirm that the fuse block is bad..

If so, and you go looking for a replacement, I think all the Audi fuse blocks that look like that are the same. Seem to be same in 4k and 5k..

Katman

Say.. Was just thinking.. You DO have power at the fuel pump jumper that you put in, don't you?

If you have no power there, the pump won't work for sure!

And, if no power at fuse 13, probably no power at the o2 sensor two pin connecter either, as it's powered by that same fuse 13...

Anyway, try jumpering power directly to the terminals of fuse 13, or as someone else mentioned, right at the connector under the back seat.

That way, At least youi'll know if the pump itself is good. Once you know that it's good, it's just a matter of finding out where your fuel pump power went to.. :-)

casem

Fuse #21 wasn't there, so I put a fuse in and now it works. Strange.

Thanks for the help everyone