gregp1962

The car won't start. The fuel pump isn't making any noise when I turn the key on or crank it. I jumped it at the relay under the dash. Still no pump noise. This makes me think the pump is blown. I'd like to run 12v directly to the pump to see what happens. But there are 4 pins on the pump. How do I know which pins to put the 12v power to?

turbo510

Look at that fuel pump connector and notice there are two sizes of wires: the two small wires are for the fuel gauge, the two larger for the pump. With the connector off, use an Ohm meter on the pump's terminals to check for motor continuity, which should be several Ohms. If you don't have a circuit, then plan on changing the pump. To check that electrical power is reaching the connector, clip wire leads to the large wire's recepticles and then to a 12V bulb, say a spare headlight bulb. It should light briefly when you turn the ignition on, and stay on while you crank the starter. I'd suggest that you do this before going much farther.

You can, as you suggested, clip wire leads onto the pump's terminals and try running it with a 12V, up to 10A, power source. Notice the polarity; brown wire is negative. If it runs, then an electrical circuit problem is likely.

gregp1962

Thanks Turbo. Looks like I need a new pump. Orederd one on Ebay. Are they hard to install? It looks like an easy job.

turbo510

Not too hard. It's best if you don't have a full tank of gas, because you have to remove the access cover and reach into the tank to get the pump out. There are how-to articals and probably videos that show how its done, but you'll need to have a pair of long rubber gloves so you don't get your hand and arm soaked with gasoline. If more than a quarter tank, you might consider syphoning out the fuel until the pump housing is out of the gas. My car is FWD so the access cover is in the trunk, however if your is a Quattro, the access is under the rear seat.

After taking the black, round metal access cover off, you'll see the white plastic tank cover with hoses and wiring. Remove the hoses and plug to keep dirt out, disconnect the electrical connector, then unscrew the large black plastic ring. Pull up the white plastic cover, and you'll see an electrical connector for the fuel gauge sensor; disconnect that. The pump assembly is removed by grabbing it and turing counter-clockwise a few degrees. You should feel a distinct snap when it turns, at which point the pump, attached by the hose, can be guided up and out of the tank opening. Make a sketch or photo before disconnecting the pump's hose, so the new one is assembled the same way. You may have to pry off the one-time crimp clamp, use a new one or a screw-type hose clamp, or reuse the original if you can reform it- what I've done though not recommended. You'll notice the wires are attached with two different-sized terminals to keep the polarity correct. Make sure those nuts are snug, because they have a critical function and arn't accessible for rechecking later. From there, put it back together. You might find the rubber gasket, where the white plastic cover fits, to give you less trouble if a little Vaseline is wiped on the contact surface first.

gregp1962

OK, I'm headed over to do the replacement. Is there a trick to turning the black plastic ring? It seems pretty firm where it is and not wanting to turn.

turbo510

If you have a set of slip-jaw plumbing pliers that can open big enough, that can usually grasp the rim of the plastic ring well enough to turn it. Otherwise, try using a wood dowel, etc, and a mallet to tap against the nubs on the ring. In any case, liberal spraying with WD-40 or similar lube will help.

gregp1962

I got it done. Turbo, your help was greatly appreciated. I got that black ring off just the way you described. Audi sure did put things in there is a strange way. For the future, I'll plan on having small hose clamps on hand.

It's a good thing the tank was almost empty. It took a bit of twisting on the fuel pump basket all the way inside the tank. The car runs great now.

turbo510

I'm sure that everybody appreciates hearing that the job worked out! Wasn't too difficult was it, after all?

Miguel241762

Hi Turbo, i noticed that you have given Really good advice, and well to cut it short, i also noticed you are one of very few i see on here that has worked on an Audi A4. My question is regarding the Door Latch on an Audi A4 Quattro. I have tried to raise the window on the Rear right door but got nothing, then a short days after the door wouldn't open from the inside, (You can open it from the Outside). i have no clue what it is , i removed the door cover, and checked the inside, but its really hard to see. so i figured i would remove the door frame inside. but seems a Lil too much, since time working on it can be cut short any moment. i need help with understanding this problem.

Miguel241762

The car is a 1996 model* (From comment below)