Shadowfax

Well here I am again begging for repair advice. My fuel pump has gone south on me (at least it is not working best I can tell). The first time it died it was in a friends driveway so I was able to leave the car while I sourced a new/used pump. I tossed the new pump in the trunk while I was trying to push the car into his garage to replace it and thought "Why not try to bump it into the garage with the starter?" So I turned the key and whalla.. the fuel pump fires up and the car does also!!! I have driven the damn thing around for about a week with no problems and it dies on me again not while running, just will not re-start. No sound from the fuel pump when I turn the key to on. I have pulled the relay and checked the # 48 and #50 slots for power and nothing.
Where do I go from here? What powers the fuel pump relay? and how do I check it?
I suspect the ignition switch,but am not sure how to test it.
HELP
TIA, Ray

Whitjr

all connections good back there?

Katman

The fuel pump relay turns on two ways:

-For a few seconds when you turn the ignition on
-When it sees pulses from the ignition coil, when motor is cranking or running

So.. If you get ignition switch gets you some action (like the gauges come on), then may not be your ignition switch (things lke the fan and the headlights don't count as 'ign working', as they are on a separate ign circuit that drops when cranking)

If you pull the FP relay out, and jumper the two LARGE slots where the relay was, pump should come on, regardless of what else is going on.

(SOMEBODY must have a picture of this, no?)

AudiSport4000

So people who ask know what two terminals to bridge. I have my nice thick test wire and could do this soon!

Shadowfax

The Bentley said to check between #48 and #50 for 12v, but Frank knows better! When I jumped the two large slots the pump fired. One new relay later and she is purring like a 5 cyl. kitten. Anybody interested in a like new fuel pump? It flow and preasure tested great, is all shinny and has a new check valve.Thanks for all of the advice.
Ray

Katman

If it turns out to be a bad relay, or one that you are having 'intermittant' problems with (as this problem usually seems to show up as)..

Take the cover off the relay, and look for a *really* thin/small crack in one of the bigger blobs of solder on the relay circuit board.

Seems that the solder is the 'mechanical' joint for one of the bigger pieces that are soldered to the circuit board. After a while (quite a few years) the solder ends up cracking, and not making contact anymore. Reheating and reflowing the solder can make it all good again.

If it IS the problem, The crack that forms in the solder is *really* thin, and can be hard to see. Easier to find if you flex the big parts on the circuit board, while looking carefully..

Then, all of a sudden "Ah ha! Caught you, you swine!"

Shadowfax

There were a couple of burned solder points (nothing too bad) and one cracked solder joint at the large windings. I'll rejoin that one and test in the morning.
It will make a good emergency relay for the glovebox.
Thanks again Frank.
Ray