Corroded main fuse panel

Your pumps and in-tank filters have to be replaced: the pumps draw too many amps.

Good luck finding a clean fuse box. Some repro were made for the 328. Could be used for your car but expensive.

 

Make sure your pumps are no shorting out, ideally remove both, you will be surprised what you can find in there. It is easy to, all the parts are readily available and not expensive. I recently did them, happy to guide you through it.

I would not waste money on getting a new fuse board, it will be expensive and not necessary. Rather what you can do it first clean all the connections, fuses and relays, and then for the high amp ones make a separate circuits - namely the pumps, radiator fans and the lights; foe the rest the fuse board is more than adequate.

 

Hi Britward,
As I mentioned on FB, I have an 86 412. Most of my discussions on this forum have been regarding troubleshooting a recurring and somewhat random "one pump out" situation.
At the recommendation of another owner I replaced my relay panel in the passenger side footwell first. I was able to source it from GT Car Parts in Arizona. At the same time I replaced two of the connectors and maybe four pins in the connectors where there were burn marks from high current draw. I also replaced all the relays, because I was there and looking to avoid the future mystery game.
I still had the same fuel pump problem although it seemed better.
Checking resistance from the white connector at the relay panel to the connector closest to the pump in the trunk, the right side was very different from the left. By this time I had already replaced both pumps and all the rubber bits that had turned to gum inside the tank. Both of the old pumps had been replaced by a PO, and still worked. I have new pumps anyhow.
There is ONE connector between the relay connector and fuel pump connector. It is at the firewall, behind the battery. Remove the battery and you should see it. A wiring diagram helps here too. I cut the fuel pump wires from the connector and wired into a heavier duty connector. Resistance to the rear was now the same from both circuits and both pumps worked. Car runs on 12 cyl, all the time.
Search for my other posts. I was working on it last year at about this time. There should be photos still there.
Good luck.


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I've posted the pictures from your thread.

Are both fuel pump cables in this connector? How did you route the new cables?
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Both are in that connector. I simply wired the second connector in parallel with the original. Added a little wire length.
I must not have been proud of my soldering job as I did not take pics! Intent was to solder the wire extensions and cover with shrink tube. It was kind of tight, so not as neat as I envisioned. A crimp butt splice with heat shrink jacket would probably work better.
I bought these connectors on Amazon; IEUYO 1/2/3/4/6 Pin Way Waterproof Electrical Connector kit 2.5mm Series Terminals Water Resistend Connectors Quick Locking Wire Harness Sockets 6sizes/9sets
Kit3/122Pcs/6Sizes/9Sets and picked one from there. $15.
I'll try to grab a photo later and post.

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Great, but how did you get the "extra" wire from there all the way to the pump?

But this still keeps all the amperage on the original fuse board.

Another way would be to add two new relays in the trunk, and have those fed independently, this way the only tension on the fuse board would only be the minimal current needed to "close" the relay.

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There was no problem with the wire. I confirmed resistance with the new connectors and left it in place.
The problem was with the connectors.

There are other options to solve the problem. I chose to keep as much of the original as made sense, esp since I had a new relay board ( new manufacturing methods vs mid eighties early multilayer circuit boards that were more likely to have failures with heat cycles).
My connectors at the relay box and firewall showed burn marks for the fuel pump circuits. The connector pins were also soft / guessing heat annealed them.

That's what I did, and it's worked for me!

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Photo of the connector. The wire is pretty good gage, but orig connector was too small. Image Unavailable, Please Login

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Clearly the 412 is wired different than the 400i based on comments above. I believe the correct solution is what I posted several years ago and seconded by 360 modena above: "Another way would be to add two new relays in the trunk, and have those fed independently, this way the only tension on the fuse board would only be the minimal current needed to "close" the relay." For the 400i my two relays are underneath the rear seats which is just above the fuel pumps and the 400i wires pass thru 2 grommets at that point. I used a #10 or 12 wire with 30 A fuse upstream of the fuse panel. Its neat and I have never touched the pumps since.
Ken

 

This is the best fix I've seen so far on the late type of fusebox:

https://www.ferrarichat.com/forum/threads/wire-diagram.564951/#post-145692676

It is also possible to beef-up the tracks with additional wires, and add silver grease to the connector pins.

 

Can you share his contact info? Cost?
Ken

 

Ken, I started a conversation about your fuseboard.