Fuel pump keeps running when ignition off ??

[Peterpolo]

Hi,

my g40 is running fine except when I turn the engine off and take key out the fuel pump keeps on running.
I have cleaned up the relays next to the ecu and tried swapping the ecu for another one because I thought it would be a earth problem but No luck?

Has any one had any trouble with this before any help would be great! and do vw still stock relays??

Cheers!

[G40supercharged]

The fuel pump relay is pulsed by the ECU while the engine is turning and this keeps the relay contacts closed and the fuel pump running. The ECU itself is powered off completely when the ignition is off so I wouldn't expect it to hold the fuel pump relay on even if it's faulty. It may be the fuel pump relay contacts have fused together inside the relay (assuming the fuel pump has a direct connection to the battery rather than going through the ignition switch - I haven't got the Haynes manual here to check it). Is it possible someone has wired in a direct connection due to a fault on the ECU or the relay? Can you switch it off by removing the relay?

[Peterpolo]

Thanks for your help buddy,

Yea are see if it turns off when unplugging the relay later and let you know, I think it does but I have just been unplugging the plug next to it for the fuel pump to turn it off,

Yea cheers buddy your proberly right I think it's more than likely the relay fused together inside, so are let you know how I get on

Cheers!

[Andy]

The relays are potted (sealed), but as they're still quite exposed I've seen dentritic growth inbetween the terminals before which was sufficient to energise the coil and activate the relay. It's worth pulling it out and checking!

[AlexG40]

The relays are potted (sealed), but as they're still quite exposed I've seen dentritic growth inbetween the terminals before which was sufficient to energise the coil and activate the relay. It's worth pulling it out and checking!

Two words. Star Trek.

[G40supercharged]

If you have a multimeter switch it to resistance, take the relay out, and measure across terminals 30 and 87 (it should be marked on it which these 2 are). This should be open circuit; a reading of a few ohms suggests the terminals have fused.

The relay is connected direct to the battery so ignition switch has no direct affect and fused contacts would always leave the pump running. The only other thing I can think of is a short to earth in the wire from the ECU as it grounds one end of the relay coil through a transistor to switch it on. If it has always kept running since you've had the car it's possible someone has connected an earth due to a faulty transistor in the ECU as these sometimes fail. 

[rumsam2006]

I've recently had this problem on my gt I just took off the positive terminal until I got a new relay, turned out that was the problem and its fine now

[Peterpolo]

Hi guys!

Right over the weekend I replaced the fuel pump relay and now all is ok,
I also noticed that it was quite wet around the relay and ecu area so cleaned up and will try keep the polo in the garage.

Thanks for the help! ;-)

[hayesey]

are you missing the plastic cover that goes on top of the scuttle tray?

also check that the drain holes at the bottom of both ends of the tray aren't blocked.  Keeping it outside shouldn't cause this if the drains are ok and the cover is there