Adi Nugroho

Hi everybody.

I want to ask something. My W210 fuel pump always turns on even when the ignition key is removed. It only stops when the battery is removed or the fuel pump relay beside the battery is removed. I checked the relay socket pin, there are 2 socket pin that always get 12v power.

What do you think is broken?

Thanks

DjaKRAbb

People mention a 'stuck relay' - have you used another relay? replace relay with a working one and continue from there

https://www.rx7club.com/3rd-generati...n-off-1022889/

Adi Nugroho

Hi,

Relay is fine. I can hear it is clicking when I put it into the socket.

bbirdwell

Relay should not activate when you"put it into the socket". It should only activate when the Motor Electronics pulls the relay solenoid to ground. Look for a short to ground on the wire that does *not* have 12 volts with key off.
Post your VIN and when I have time I'll see if I can look up wire color and connector/pin number. Also check Pelican Parts' fuel pump troubleshooting section in their tech articles.

Adi Nugroho

Thank you for your help. VIN is MHL210037OL032298.

Can you share with me the Pelican Parts URL? I already search it but not found the "fuel pump troubleshooting" article.

Additional Information:
I change the K40 and I still have the same issue.
I check the relay under the rear seats using a voltmeter and found that one of the terminals (86/85 not sure which one) always got around 9-12V which I believe should not get that voltage except I turn on the ignition key.

bbirdwell

Adi, PM your email address to me so I can email you some information.

Adi Nugroho

I sent you my email address.

bbirdwell

Adi, check your email.

Also, reviewing the schematics, I found another plausible explanation which would negate my email explanation. Remember, the following is for a 2001 W210.

In this hypothesis, the ME pin 1, connector "D" is always connected to ground internal to the ME box. The fuel pump relay pin 6 should NOT be hot with key off. That pin is supplied by fuse 5 in the passenger side fuse and relay module box. Fuse 5 is powered by the "polarity protection relay (PPR)" (top of page 17) which, in turn, is activated via the ME through the electronic ignition lock control module (top of page 16). In this case, the ME supplies 12 volts to activate the PPR which then supplies 12 volts to fuse 5. If you have this circuit (big "if"), and fuse 5 is always hot, the PPR relay is most likely stuck in a "closed" position. To verify, leave fuel pump relay inserted, and begin pulling the other relays until the fuel pump quits. If so, that is most likely point of failure.

Remember, I am a shade-tree mechanic, not factory-trained, so perform at your own risk.