456 cutting out 7-12 every now and then

have had this a couple times, and currently in the shop for a similar ailment.
possible causes
- ecu is out. yes you have to replace since it is a sealed unit. they are expensive - about 2500 chf/per side.
- coil is somehow defective, pls have technician check
- o2 sensor, have tech check
- a few spark plugs or wires, pls have tech check
- fuel pump - this is the current track that the dealer is on with my car.

 

Roos, did you change the ECU already? How did it turn out?

 

They think the ecu is ok and trying the fuel pump now.

 

There are two (2) crank position sensors - one
for each bank - at the lower rear of the engine
that can create this problem.

Swap them.

If the problem changes sides,
you have your answer.

Try the same thing with
the two - yes 2 - engine ecu's

 

How did this turn out ?

Yes, the 456 cars are VERY hard on fuel pumps,
and they will stop a bank of cylinders.

Scott

 

550 as well. I had a cracked pressure hose on one of my pumps and it took out an entire bank. Well, it provided enough pressure to idle, but no more.

 

It is my understanding that the fuel pump itself is quite robust, but the weakness is with the rubber associated with the intank system, correct?

 

Yes

 

see my posts on the Fuel pump gaskets.. takes some work but source the gaskets from Alfa and save a bunch. what you describes could be a tank full or rubber pieces clogging the fuel flow, just like mine did

 

Good advice.

I am at the point where every time I get a
456 or 575 (4 total) I automatically go into
the fuel tank ( not that hard, - if the car
is almost out of gas....) and look at the rubber bits.

If there is ANY visible deterioration of the
black rubber parts, I replace the rubber stuff.

While in there, I usually just also replace
the fuel pumps, too, and forget about it.

Also not a bad idea to replace the fuel filters
near the tank (these have often been ignored
for the life of the car)

IF there has been "rubber sludge" in the tank,
change the filters again soon,
or the sludge will "block: the filters again,
and you go to 6 cylinders again...

Cheap and quick to do.

 

There are no rubber part in 575 pumps, completely different from 550/456 pumps

 

Dave-Are the 575 pumps interchangeable with the 550 or 456?

 

Not directly, see this for more info.

http://www.ferrarichat.com/forum/456-550-575-sponsored-bradan/417423-575-fuel-pump-550-a.html

 

Another thing I toyed with doing was using sheet Viton and rolling it around the pump, essentially making a gasket ( sort of a "pig in a blanket" manner) for the pump to be surrounded by. I actually bought sheet Viton, as it shouldn't degrade the same way the gaskets do over time, but making something I felt really secure about proved more challenging than I thought.
In the end, I used the Gasket from the Alfa 164 and it ran great. Hope the OP you can solve his problem easily- TZ750 is on the right track for sure with his list of differential diagnoses, but in medicine we always stick with "common things are common", and in the 456, the newer gas destroys the gaskets in them. Dave, IIRC the tank covers are different on the 456 and trying to go gasket-less with a 575 system isn't easy. Its been a few years but I remember looking at every possible option, because no one in the USA had any gaskets for the 456 pumps at the time mine failed. I even called italy- they said occasionally, when forced by market, they make a production run of the gaskets but its of the same crappy material. I even looked at fabricating my own tank plate covers, making a 575 like system. But, When I pulled the pump and realized it was the same set up as the 164 ( even the same model number bosch), i just stuck with that. One of my pumps was destroyed by the Rubber particles and that accounted for my right bank being out.