TR Fuel pump help

First thing to check for such intermittent operation are the contacts in the "y" white connector and on the fuse-relay PWB for the fuel pumps -- they are the positions with the large P (beige) wire and large PN (beige/black) wire. Look for signs of "overheating" as shown in these photos:
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These M (brown) wires are the AC +12V power -- another high current connection that often has trouble.

Yes, that's your fuel pump trouble.

The weak point is the small contact area (and small contact force) between the male and female connector parts (which generates a lot of I^2*R heat because the current is so large, causing the resistance of the connection to go up, which generates even more heat, in a death spiral to failure). If you do a search on "TR white connectors" you should get many threads on the subject with many possible solutions. My personal solution was to add another high current capable wire directly from the relay terminal 87 to the corresponding wire leaving the white connector. This photos shows the interior detail for the wires I initially added for the AC and water fans:
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but I eventually also added wires for the fuel pumps (two yellow = AC, light blue & light blue with black = water fans, brown and brown with black = fuel pumps):
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And this photo shows the corresponding brown and brown with black wires added into the harness to bypass the white connector for the fuel pumps (note that it also shows the same "burned"' AC position in the "k" connector):
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First, I need to correct myself, because, on the fuel pump relays, they used terminal 30, instead of terminal 87, as the "output" terminal to supply the +12V to run the fuel pumps (so, in that case, I added a high current capacity wire from terminal 30 of each fuel pump relay to the P and PN wires in the harness leaving the white connector).

I believe the reason that the PN wire terminal has more trouble than the P wire terminal (even though they carry the same current) is related to the trace geometry on the PWB. This jpeg that Robert Hayden took during his PWB repair shows that the trace for the P wire is quite a bit wider than the trace for the PN wire -- so this helps conduct the heat away better from the contact point between the male & female terminals so they would run at a little cooler temperature for the same I^2*R heat input (this is the "backside" of this layer so you need to reverse L-R to have the same view as when you face the PWB in the car).
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Uh oh Rocco, I hope you're not down for to long.
Although, with Steve's direction I think you'll be up and running in no time. He's a wealth of information, way to go Steve!

 

Is it possible that the fuel pump is getting weak, drawing excessive amperage, putting heat into the board at its weak point? It would be easy to check with a clamp on amp meter. Steve, thanks again for you detailed pics and explainations. I have been randomly printing them to put in my TR shop manual for future reference.

 

Sorry about that Rocco -- didn't mean to cause you extra work. It is indeed exactly as you are guessing here -- the early F113A euro TR use the 87 terminal of the (...113) relays as the output terminal for the fuel pumps; the US F113A040 TR (mine) and late euro F113B TR (Robert Hayden's) use the 30 terminal of the (...101) relays as the output terminal for the fuel pumps.

 

I would call what you (and I) did a "permanent fix" (compared to just replacing the stock parts -- which would just have the same high probability of having a future problem again IMO) -- at least I'm counting on it being permanent . Haven't heard of anyone doing a "better" overall replacement, but there have been some other reasonable fixes IMO that do address the poor male-to-female connector contact -- like some going to a female spade connector that grips the stock male tab connector on the PWB better (although that makes it harder to plug/unplug):
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Glad to help out, and glad to hear that it seems to have resolved the problem (and thanks for leaving the feedback -- it's very frustrating for me when someone asks for help with a problem, and gets some good suggestions from the members, and we never hear about the outcome).

Couldn't agree with you more that it's a question of "when", not "if"

 

Steve, i soldered my wires to the actual circuit board, though with hindsight i should have used the corresponding coloured wires. Just wondered if yours is a better fix than mine or if there's no difference?
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Hi Si,

You have done a great job there but I cant understand why have you wired up to pin P75 of the "w" connector?

 

Because that terminal was burnt Phil and it is P60 on the "Y" connector which is the fuel pump (beige/black) which goes to P75 on the "W" according to my information.

http://www.ferrariaustralia.com/Technical/Testarossa%20Fuse%20Panel.pdf

 

I have taken the Robert Haydens diagram and added some further information to help others.

Will you all take a look and check that I have it correct - Thanks

I noticed that Robert added another wire fix and that goes from fuse 5 to P29 and I dont understand that, any ideas?


http://www.ferrarichat.com/forum/attachment.php?attachmentid=931083&stc=1&d=1241437780
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If you are right then Barabus may have his wired up wrong as he is using R70 and R75 as shown in his photo above
I am off to research some more.

 

Barabus has a F113B (late euro) TR which uses terminal 30; Rocco's is a F113A (early euro) TR that uses terminal 87.