Thread: Fuel Pump Permanently On
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Old Jul 18, 2015 | 11:40 AM
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BrenLW's Avatar
BrenLW
Joined: Jul 2015
Posts: 5
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From: Manchester, England
Default Fuel Pump Permanently On
Hi Guys,

I'm actually a 2002 SLK 320 (R170) owner but I believe that the SLK and Crossfire are close relatives from what I've discussed whilst trying to resolve this issue.
I hope that's correct and you guys don't mind me seeking assistance here.

Anyhow, only had the SLK a few weeks and the blue 15amp fuse in the F5 slot of the K40 relay (Relay Control Module) kept blowing.
(On UK models the K40 module sits under the bonnet (hood) on the drivers side right next to the battery.

I noticed some electrical tape in this area so I undid it to find this mess.

http://s18.postimg.org/jrkyssjrd/01_Wiring_Mess.jpg

The red wire (yellow arrows) had been cut in half and one end taped up and left dangling, the other end crudely joined to the pink/green wire (orange arrows)

I undid this mess and returned it to its original set up the best I could.

Hey presto the fuse has stopped blowing however now the fuel pump will not turn off.
At least I think its the fuel pump, its a humming from behind the rear wing where the fuel cap sits (drivers side).
Its constant, I have to disconnect a wire or the battery if the car is left for a few hours otherwise it drains the battery.

What would the reason be to rewire the area shown in the image?

They've also knackered the plug on the end of the dodgy wiring that connects to the K40.

http://s18.postimg.org/5jva4572h/02_Plugs_Mess.jpg
http://s18.postimg.org/dbc02pb7t/03_Busted_Plug.jpg

Other than the fuel pump issue the car now runs fantastically, I do a 35 mile round trip commute every day. Is it likely the fuel pump is knackered even though the car runs great, could it be the K40 or the relays inside it even though it looks like new, the solder seems great, there are no charred areas at all or cracks, I've done a lot of reading on this K40 module I feel like I know it well, or is it likely to be the wiring itself between the fuel pump and the engine bay?

I'm happy to send it to the garage but I want to try and learn things before I pass it on and I have little faith in the diagnostic skills of 'some' garages if I'm honest, been burnt before.

I'm trying to locate a replacement for the busted plug but no internet search is showing anything resembling that plug, anyone know what it's actualy name or part number is?

Any suggestions would be most welcomed, I hope the images load ok and this is enough info for you guys.

Thanks in advance, Bren
 
Attached Images
File Type: jpg
Wiring Mess.jpg (130.8 KB, 175 views)
File Type: jpg
Plugs Mess.JPG (127.5 KB, 129 views)
File Type: jpg
Busted Plug.JPG (62.6 KB, 135 views)
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