Burnt Fuel Pump Wires
 

With the help of member 80stech, I have traced my non-start issue of my E70 x5 4.8 to either the fuel pump or the fuel transfer pump.

Just yesterday, I took apart and removed the rear (comfort) seats. This allowed access to the fuel pumps under the seats. Upon removing the carpet, I can see that the wires have melted. Now I am not sure if this is normal and if it is the reason for the no-start with no fuel pressure. Has anyone experience this?

https://imgur.com/a/GrlAKwK

I might be wrong but I think that is a known issue and maybe even was a recall ??

Yeah, I think there was a recall, and I think it was done on my vehicle already in ~2017? Unless they botched the job or didn't replace anything. The wires seem to be in pretty poor condition. Should I contact BMW of North America if it is recall related?

Yes, you could try that.

Quickly looking at the recall information from the NHTSA government website: https://static.nhtsa.gov/odi/rcl/201...6V746-7192.pdf

I see that the wire that was melted on mine seems to be supposed to be part of the recall, and should be replaced? I want to make sure that I have valid reason to contact corporate BMW first.

I’d call your local dealer and tell them you have a car to bring in for the recall, vin: xxx. Let them sort it out. Maybe toss in the conversion the fact that the fuel pump wires seem to be shorting and arcing. That should get their attention.

I was digging through my service history receipts, and found that the Airbag and Fuel pump and harness recall was performed on Nov 7, 2017. And the car doesn't start, so I can only tow it to the dealer :(

Dealer receipt/report from 2017: https://imgur.com/a/Xwnqa2B

You can patch the wires to get it to run just leave the seat off and make sure everything is insulated.


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It's not really the wires that are the root of the problem it's excessive resistance in the connections.

If the connectors are melted then might be a solder situation. That's pretty scary to see. Hopefully that is covered under recall

This happens because someone cheaps out on the metal used on the contacts. If the harness was repaired under the recall and the pump wasn't, then it's possible only half the problem was fixed heading towards the same problem happening again. Even worse, if the connectors on the replacement harness aren't much better than the original ones.

Burnt Fuel Pump Wires
 

Deoxit pro gold! Any contacts. I've literally measured a 160x improvement with two drops of the stuff In a maglite contact!


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I bought a new harness (61-12-9-387-439), stripped some new wire, and redid the connection. I put heat shrink over the connection, and also electrical tape over the heat shrink.

The car does not hesitate when going uphill anymore. However, the wires are slightly warm to the touch. Is the warmth normal?

Again, the critical part is the connection, if the pump side of the connectors are poor quality and/or oxidized you still might have a problem.

Crimps/soldering needs to be done properly as well.

I am assuming you are talking about the socket that plugs into the pump? The part number that I included in the last post includes the socket. So it is new.

I soldered the wire. I first twisted the stranded wire, then tied it in a Western Union knot. I then put solder over that. After that, I head shrunk the connection.

Usually the warmth is from the connection. Did you apply any connection help? Deoxit Gold is the best I've been using since the 90s.

No connection help, just Western Unioned the wires, soldered, and heat shrunk it.

https://imgur.com/a/6UKKFPa