Waterlogged 99 Boxster

[ARModen]

Ok, so further investigation leads me to believe the fuel pump is bad or plugged up. I disconnected the line on top of the tank and attached my siphon line. I then hooked up the battery and turned the car on expecting to use the fuel pump to pump down the tank. Nothing came out. I tried with my siphon hose attached to each line and same result, no flow. Not particularly the safest operation, but if it was bad gas, using the fuel pump to pump the tank down would be the fastest fix.

I checked the fuel pump fuse (C4) fuse wasn't blown and that there is 12V there. There doesn't seem to be 12v across the plug on top of the tank though.

So either it is the fuel pump and I'm not reading the plug right, or maybe theres some relay in the circuit to control the fuel pump that I'm missing. My ancient 911 fuel pump pumps till the fuel rails are full then stops by itself.

So if there is anyone thats familiar with the fuel system I have a few questions:
1. What would prevent gas from pumping out of one of the three pips on top of the fuel tank?
2. Is there a relay somewhere between the fuse box and the pump?
3. What should I be seeing across the pins of the plug on top of the fuel tank.
4. Mostly importantly, how on earth do you get that ring off there to get the pump and level sender out?

[ARModen]

Apparently there is a relay. Now I need to find it, and see if it's bad or if it's indeed the computer or alarm system thats disabled the pump.

[Paul]

As always use at your own risk:

I would apply 12v to the fuel pump (plug unhooked) to the terminal that is fed by the gn/wt wire and ground the terminal fed by the br wire.

There are 2 relays involved:

fuel pump relay in position 13 on the relay panel in the left foot well.

the MFI/DI relay in position 1 on the relay board on the left side of the firewall in the rear trunk.

the pump is fed by a 25 amp fuse in c4.

[Paul]

VW special tool 3217 is used to remove the fuel pump. Spec is 52 ftlb so it is tight.

The fuel pump relay can be jumped by connecting posts 30 and 87 (3 and 5).

[ARModen]

Thanks Paul. I did some more checking, I checked the fuel pump relay and it was good, but when I jumpered it out and turned the car on I can now hear the fuel pump running. I'm charging the battery on the charger now and I'll see if it starts up. The fuel pump runs continuously right now even when the ignition is off so this can't be a permanent fix.

So now the question is where does the control signal for that relay come from?

D Williams said:
"Just for fun.. if it's been raining that much, check under the drivers seat and see if it's wet?? lost my control mod due to water. It controls a ton of stuff. If it's wet water will enter the box from the back side lower plug and ground things out. It can be causing the alarm to kill the spark. Engine will still turn over but will not crank."

So next place I'm going to check is under the seat. I don't see any water or water marks behind the drivers side, but maybe I go some in around the doors considering the weather that week. I believe that's the alarm control module. The durametrics thing didn't report any errors in any control modules so maybe it's just a bad wire.

[Paul]

http://www.samstagsales.com/vwaudi2.htm#fuel

[ARModen]

Haha, that's a $300 factory tool! Only Porsche...

Luckily I shouldn't have to get into the tank now as long as I don't burn up the pump with my current set up. Battery is almost charged then I'm going to start back tracking the control signal for the relay.

Any tips?

[Paul]

Originally Posted by ARModen

Haha, that's a $300 factory tool! Only Porsche...

Luckily I shouldn't have to get into the tank now as long as I don't burn up the pump with my current set up. Battery is almost charged then I'm going to start back tracking the control signal for the relay.

Any tips?

right above the real one is a $134.50 alternative.

Note that this is a VW tool, oh wait VW owns Porsche....

[Paul]

The DME through relays 1 and 2 in the rear and relay 13 in the front are all needed for the car to start.

FP relay control is pin 63 on the DME

[ARModen]

Originally Posted by Paul

The DME through relays 1 and 2 in the rear and relay 13 in the front are all needed for the car to start.

But will 1 or 2 in the rear turn off the fuel pump? I'm going to start it in a sec here when the battery charger is done, but I assume the ignition system is working and I'm getting a spark because it was running poorly after the problem arose. So I think it was firing but becoming fuel starved.