Infamous pink wire

ALF750 · July 11, 2015, 07:56:33 AM

Once again I have crossed swords with the infmous pink wire (pink/white actually) that supplies power to the electric fuel pump (or, is meant to supply power) on the 75TS. I thought I had this weakness fixed by bypassing the connectors in the loom (RHS fwd of firewall and behind above fusebox) and securing/heat shielding the four EFI relays on the LHS inner guard. But last evening, far from home, it stopped without warning. After checking all the usual things a call to an experienced friend yielded a temporary solution - lift the back seat and connect the yellow tail light wire to the pink fuel pump wire (requires cutting wires of course). And off we went, as the first drops of rain started to fall and the sun set. I owe you a bottle of your favourite Julian.

So, I'd like to ask the collective wisdom is there a definitive fix for this problem, or a recommended approach to re-wiring the fuel pump circuit completely, before I start re-inventing the wheel?

Divano Veloce · July 11, 2015, 08:28:39 AM

I recently purchased a 75 twin spark that had a wire running from the battery to a switch in the cabin and then down to the pumps.... no fuse of course.

What I found was that the pink/white wire had simply come off its terminal on the back of the fuse box. I gave the terminal a squeeze with a pliers and reattached it and all is now well (with the fuel pump wiring anyway....)

I hope you find something as easy to fix as this!

ALF750 · July 11, 2015, 01:38:19 PM

Yes, I have heard of the permanent just-in-case wire - I was hoping for something a little more elegant! My thought was carry an emergency jumper wire that plugs in to the rear cigarette lighter socket that will reach to a blade connector on the pink wire under the seat. Not elegant either and fails the beloved wife test. I'll search further re. fusebox and miscellaneous connectors. I read a blog about a guy and his Ferrari (testarossa) from this vintage - sounded very similar with scorched connectors and plastic trim turning to goo. Apparently they sometimes even catch fire!

GTVeloce · July 11, 2015, 03:21:19 PM

I had huge problems with this but the final thing that actually solved the problem for me was replacing the green black wire that goes from the ignition switch (well, actually the brown wire when it comes out of the first plug) to the set of four relays. Mine had got old and hard. It was obviously struggling to carry the current to feed the fuel pump relay. I just fed the wire from the ign switch plug, through the firewall grommet, across the back of the engine and down to the relay.

In the mean time, a quick fix (if you need to get home) is to disconnect the lambda heater as it is fed from the same fuel pump relay and uses precious little electrons!

GTVeloce · July 11, 2015, 05:45:56 PM

To make my response clearer: I too was not getting current through to the fuel pumps. I ran a new wire from the fuse box to the pump direct (bypassing all plugs). Problem returned. I ran a new wire from the relay direct to the other new wire. Problem returned. Installed a brand new pump. Nope. I then discovered if I disconnected the lambda heater it would sometimes work. So I looked further up the tree and discovered the relay is fed by this green/black wire. Changed that and have not had a problem since, including reconnecting lambda heater and routing new fuel pump wiring through the fuse box as per the original.

I suspect most of my work was a waste of effort as the real culprit for me was the green/black wire.

ALF750 · July 11, 2015, 10:36:11 PM

Thankyou GTVeloce for the description. I'll have another look at it tomorrow. Thanks all.

ALF750 · July 13, 2015, 08:42:29 AM

Sorry, couple more questions....is this a 75TS only problem, or do the V6 75/Milano also suffer? Or, is it only RHD 75TS??

shiny_car · July 13, 2015, 11:39:40 AM

It can be limited to the TS because of the specific relay setup. But it depends where the fault lies. The V6 does feature a pink/white power wire to the fuel pump originating from the Combi Relay in the engine bay.

Craig's Place description of TS relay sequence: http://www.users.on.net/~craigf/ts_start.htm

Generally, I think it's a good idea to upgrade the power supply through the pink/white wire, by using a relay. The pink/white wire can trigger a relay (ie: go to terminal 85 on a typical SPST Bosch-style relay); then take a dedicated power supply to feed through the relay. You can take a power feed from the fuse board and mount the relay in that area which is also where the pink/white wire passes, so it's all relatively within easy reach.

ALF750 · July 13, 2015, 02:29:47 PM

Thanks Shiny, I've trawled Craig's 'site quite a few times, and this one http://www.alfamilano.com/. Haven't found a TS-specific wiring diagram yet anywhere on the web, only older combined 1.6/1.8/2.0/2.5 manuals and diagrams. Relay sounds like a good idea, but need to find my fault in the pink/white wire yet. I have a short after fuse #13 somewhere.

Divano Veloce · July 14, 2015, 09:20:46 AM

http://david.alfa-romeo.eu/alfa/AlfaRomeo75/
and
http://david.alfa-romeo.eu/alfa/75/

lots to download and sift through!

Divano Veloce · July 14, 2015, 09:35:24 AM

http://david.alfa-romeo.eu/alfa/75/75_ee_diag_e.zip

this file contains the diagrams below as well as the key to wiring diagrams (E-119 to E-125) and wire colours (file E-003 to E-004)

ALF750 · July 15, 2015, 11:41:21 AM

excellent, thankyou.

GTVeloce · July 15, 2015, 03:17:28 PM

These may help as well. Especially if you are chasing fuse 13. IIRC the output of fuse thirteen goes into the loom above the fusebox and down the drivers side (RHS) of the floor all the way to a plug underneath the right rear seat. It then splits into two with one going to either of the pumps. I quick check with a multi meter will tell you if there is an issue in the continuity of the wire. Also, check the earth to the main pump at both ends. On the pump itself and where it connects to the body which is also under the right rear seat. No harm in giving them a good clean and spray with contact cleaner while you are there.

GTVeloce · July 15, 2015, 03:18:08 PM

Too big for one post.

ALF750 · July 17, 2015, 10:03:38 AM

thanks, I was wondering about the routing of the pink wire. I definitely have a short in that run, and plan to retire that wire from use. Found the pump wire earth point on the inner sill - all clean now. Also pretty sure that connector H6 on the back of the fusepanel is the supply to the pump/pink wire. My current plan is to run A NEW CONTINUOUS WIRE FROM h6 that switches a relay under the rear seat. Then, take pump power from the rear cigarette lighter circuit (maybe) or run a dedicated power wire from the battery, or the L connection on back of fusepanel. Thoughts?