No power to the L/H bank fuel pump

I have a problem with a 1990 Testarossa. The fuel pump feeding the left hand bank has no power to it. I've done all the usual checks around the fusebox and there's power coming from there. Fuses and relays are ok and connections are not burnt. There is power out. There appears to be a break in the wire from the fuse box bottom connector to the pump itself. Any ideas where the break is likely to be? Is there a connection somewhere that may have worked loose?
Thanks in anticipation!

 

Hi Steve
Thanks for the reply. Yes, checked the output at both pump feeds from the fusebox and all is present and correct. If I run a wire from the box output direct to the pump, it runs as it should. A bit of a mystery! It would appear that I just have to run a new feed from the box to the pump.
Just to add to the confusion, it would appear that I also now have a cold start problem.
All fine when fully warmed up but very reluctant to start when cold.
I'm guessing the brown sensor but havent yet checked the resistance. Anyone know the correct fuel pressures off hand? I'd like to check that these are ok.
Thanks again!

 

The car is a 1990 Euro spec.
Not sure of the engine family. No cats. Its a new acqusition for a friend of mine and it started well enough when we initially saw it (a week ago), even when cold, though the performance was very flat. This was clearly because of only running on 6 cylinders.
There is a good spark on both banks and all 12 are now firing with the pump wired externally, though the left bank (7-12) seems to be a bit weaker, somehow. Its taking a longer time for the exhausts to get properly too hot to touch, whereas the right bank is heating up quickly. This is the bank (7-12) that also has the fuel pump problem.
When starting cold, it is very reluctant to catch at all. When it does eventually catch, any throttle immediately kills it and it will only catch on no throttle. During warm up, it eventually starts to accept throttle but pops and bangs a bit. When fully warm, it responds ok to throttle with perhaps a hint of hesitation. I'm guessing there should be none.
On reading other posts, sounds like it could be tachometric relay perhaps?
Cars had new plugs, leads, rotor arms (they were all a bit flakey).
Compression is 160psi+ on every cylinder. The service history shows that it had the fuel metering heads cleaned and recalibrated about a year ago when it had an engine out cam belt service.

 

Well, its an F113B engine, as suspected.
And, there is no power at the red wire when cranking. So, the diagnosis of a faulty protection relay may well have been spot on. Any other checks to confirm this? I'm about to delve into the front to check out the relay.

 

Apologies... I'm muddling my front and my back ... always dangerous!
Checked out the protection relay in its magical box and found a fault with the wiring inside the box. All repaired and the engine fired up immediately and runs smoothly.
I think I'm nearer solving the pump wiring too. Behind the fuse box, one of the pump feeds (the faulty one) disappears into a plastic black box and reappears again. Definitely a lot of non-Ferrari splicing been going on and I'm guessing this is where the problem lies. It may be part of an alarm system. Not sure yet!
Fuel pressures are both identical so no pump problems evident, though one bank still seems a little weak.

 

Yep.. now Ive unearthed it the box is marked with an alarm sticker. I'm guessing its one of those darned Valet mode units to reduce the power by cutting out one bank. Well, its faulty!

 

Missed out the faulty alarm module and now have two pumps working as they should! We also have a car that starts on the button and runs very nicely. I think that the weak bank is in need of an 'Italian Service' - probably after running for so long as an air compressor! It seems to be getting stronger all the time.
I must thank Steve for your absolutely invaluable advice. Your posts are real 200% posts - you answer the query in full and give every bit of surrounding advice unprompted. Without your info on the protection relay, I'd have been on a wild goose chase all over the place. Even though the relay wasn't faulty, you pointed me in the right direction. Thanks again. Your knowledge is quite remarkable.

 

Hi Steve

The fault was with the red wire that goes to terminal 87 of the protection relay. It was kinked over just before the crimped terminal at the relay and had broken internally.
I just cut the wire further down and fitted a new terminal. All the other wires were absolutely fine.

Another area where the connections were not as good as they could have been (showing a slight resistance) was where the round multi-connectors actually connect to the box. A good clean with contact cleaner and a coating of contact gel and all was measuring A1.