backdoc

Well, I just replaced the ignition switch. Pretty easy job, and the ignition switch was cracked just like the one on Audipages. The car still won't start. So far, it has a new fuel pump relay, and a new ignition switch. The only new info is that I got a new code off the vag-com. 18010-power supply(B+)terminal 30, low voltage. What now? Start checking the ECM? It is not fun troubleshooting when it's 18 degF out.

PaulW

Let's assume you have compression.

You have been focusing on gas.....did you try to run the car with the fuel pump mechanically operated as you did in the test?

That's what I would try. The low voltage code is just because you've been turning it over so much.

What Engine codes do you have? Clear them all, then try to start the car and post them up.

backdoc

Hey Paul,
Right now the battery is charging b/c it was dying trying to start it. I tried manually activating the fuel pump relay like I did before, but this time no gas came out of the fuel line. The battery was pretty dead, so I just assumed that it was too low to even activate the relay by hand. When the battery is charged, I was thinking of trying to start it with the fuel line connected, and manually activating the fuel pump relay to see if I can start the car. Is this a good idea, and how long should I activate the relay? Thanks a lot!

PaulW

If it doesn't start, deactivate it.

It sounds like your fuel pump is dying....they usually die a slow death and your waiting at McDonald's make sense.

My 91 200q fuel pump died....two or three times before it fully died. It's the motor that dies, so sometimes it gets turning again and you are good to go.

backdoc

If the fuel pump was bad, would it prevent the fuel pump relay from activating? And if I need a new fuel pump, where do I get a new one, and can I put it in myself without too much trouble? I know how expensive they are, and don't want to do it unless I am 100% sure that it is indeed the fuel pump.

mpollan

<ul><li><a href="https://forums.audiworld.com/a8/msgs/152013.phtml">https://forums.audiworld.com/a8/msgs/152013.phtml</a</li></ul>

backdoc

So I charged up the battery, and took the cover off the fuel pump relay, and disconnected the high pressure fuel line. When I turn the key in the on position, the relay activates and then de-activates. When I crank the engine, the relay activates on its own, but no fuel comes out of the fuel line. So I must be looking at a fuel pump or sending unit. It looks like the relay is doing what it's supposed to do. Now what?

tozoM8

You need to test if there is power going to the pump. Have someone to turn the ignition on while you testing the power by the pump. It will have power for 1 sec. If there is power, you need a new pump.

BrianC72gt

while cranking...then it waits for the ECU to tell it the engine has started and then it clicks closed again and the pump runs continuously. This is a safety feature so that if the car crashes, engine stalls, and the line ruptured, the pump would not continue pumping to lessen the risk of fire. All fuel injected vehicles have some version of this feature.

Also check for a blown fuse for the fuel pump also in the driver's footwell, but on the side in the fuse panel. When my fuel pump died siezed, I would constantly blow this fuse due to an internal short or overload inside the fuel pump motor. If you have VAG com, you can do an engine output test where VAG com will tell the various bits associated with the engine management system to open close and cycle, then it reports back how they all performed. If you get no fuel, the next step would be to test for power at the fuel pump with the relay jumpered (you won't hurt it, it is always engaged once the engine is running) if you have power there, but no fuel, then it is time to do the fuel pump. I've done two...I work for beer....good beer mind you...and I'm in NYC.

You've got gas in the tank right? No insult intended, this is the kind of thing would ovedrlook in my frustrated fervor, but you HAVE pumped out a bit of gas, no?

If the pump does work, then I would check ALL of the important underhood ane engine bay fuses because that car wash is suspect in my mind. A slow draining cowl will do as much damage as a completely clogged one...well not really (search "as Boot") but it could casue you ECU to get wet and wonky. Know anyone with a spare to rule that out?

You do have a yellow check engine light when you turn the key to run or starts, right? You should. If not the ECU is not getting power. I'm getting a bit random. The four wire connector passenger's side under the three screw access cover is your next stop two wires are for the fuel gauge and two for the pump. My Bently is out of commission. Figure out which one is the hot for the pump, hot wire the relay and confirm 12 volts there WITH THE WIRE unplugged. If it is plugged in and the p0ump is shorted you may see something well below battery voltage.

backdoc

Not sure if the new switch fixed the relay, b/c I previously didn't pay attention to the action of the relay while turning the key. So to test power to the pump, I hook up my multimeter to some wires in the trunk while someone cranks the ignition?