Issue with fuel pump, and have replaced with a new Walbro, but now need to run down electrical issues related to the pump. The fuel pump fuse did not blow (was correct amp) and instead melted the fuse block (see picture). anyone know how to remove the wiring from the fuse block? would like to either remove the fuse sockets and clean up the block, or install a separate fuse for the pump. all of this after tracing the electrics looking for any issues, but also looking for suggestions as to where to look. thanks

[img]https://docs.google.com/document/d/1OxdjXI5lDZDcJ8SgMSAKWzu24CRS3WiCbzmePoD10Ng/edit?usp=sharing[/img]

Ouch - how very Morgan. I would be very cautious with the wiring if I were you and perhaps get an auto electrician to look at it unless you really know what you are doing. Auto electricians can appear expensive but far better than a fire.
Chris

Welcome to Talk Morgan Louis. I would suggest that the problem was not the fuel pump but a poor connection to the fusebox, high resistance at the connector leads to localised heating. I think there is a spare fuse space if the holder is damaged beyond recovery at that location.

thanks for the welcome...glad to be part of this group.

agree on the high resistance, as i've been tracing and checking the circuit back to the pump and have not yet found any issues. the spare fuse space is already taken (the fan kit used that slot), but i can add an auxiliary fuse block and move the fuse there (second fuse block is planned to support fog lights, heated vest for winter driving, etc.). issue is i cannot disassemble the fuse block. one of the locking slides comes out easily, but the other is stuck...likely melted to the block from the heat...and the wiring to the block is too short to turn it over to see what's going on. any suggestions on how to remove the fuse block greatly appreciated.

Looking at the distortion I wouldn't bother trying to re-use that fuse socket, as it will also have heat damage to the connector / cable below & oxides leading to bad continuity

I would carefully snip out the two wires from below and add in an inline fuse holder on fly leads with soldered connections into the existing wires, plenty of options online that take the same blade fuse as OE, you may even find a holder that clips onto the end of the existing grey base in your photo

I changed the walbro 250 liter hour pump to a walbro 160 liter hour pump, it consumes fewer amps and less noisy, it may be GS 278 the reference.

Thanks for the info, and wonder if this isn't a common problem (well, at least more than just the two of us). happened to me with the stock pump, although if the issue is a faulty connection in the fuse block this would melt the connection but not blow the fuse. just odd that we have the exact same symptoms, but in any event, have now solved with a solution just like yours.

It is not a common problem, most failures are of the original specification fuel pump, not the power supply. There have been very few (none?) fuel pump failures reported after changing to the Walbro GS342 fuel pump. The Range Rover V8 EFi owners researched the issue with the standard pump pretty well, although I will agree it is vastly over specified for the S&S X-Wedge requirements.

I think your problem is with the fuse box installation and it's poor connectors. Maybe a good idea to break and make the fuse box connectors to ensure good connections? I suppose we have a mentality that M3W's are still "new" cars and shouldn't suffer from problems like corroded electrics, thats for "old" cars, but some are now over 10 years old and have sat in cold damp garages. Not saying that applies to your car Louis but it may to others in the future, you may just have a loose connector.

This is not at all unusual Louis in any electrical circuit high or low voltage, AC or DC. The heat damage occurs due to build up over a significant amount of time often due to the tiniest additional contact resistance allied to constant significant current draw. The power (i2r) loss that creates heat at this point being proportional to the square of the current! In your situation this won't cause an increase in overall current draw from pump, it might even be a tad less so fuse won't be effected.

As an example I had a suitably fused high current DC connection on a boat secured solidly through 15mm plywood by M12 nuts and bolt. This hefty fixing got so hot it charred the wood that supported it!

I suspect you either has some moisture/dirt grim or the fuse wasn't in snug, leading to poor contact. That will lead to heat which will make the contact worse over time until you have a failure. I would take out all your fuses and clean with contact cleaner and reinsert them just for good measure.