cut-outs after reving above 4500rpm

[iani]

Do you have a fuel pressure gauge? It would be useful to see if the pressure is dropping at higher RPM, that would suggest either too narrow a fuel pipe or, more likely, a tired pump.

[GinettaG15]

as said above: the problem is present with mechanical pump and with electric pump..so it cannot be the pump. the fuel-pipes are the usual ones...nothing too narrow...those pipes could feed a 8L v8 engine

[GinettaG15]

Problem solved!!!!

i was right in my assumption "the problem must be fuel related"...but i was wrong with the Needles.

It was the fuel-pump!!!

how comes? the car was originally a 2000cc model....the pre-previous owner fitted an electric fuel pump (his garage fitted it!!). the pump was from a quality brand "Hüco" (they say "made in germany"....but its also distributed as Hitachi Pump...the pump costs ~80pound). this pump is often used from historic car owners to convert from mechanical pump to electric pump. due to its low-pressure which makes it easy and simple to install without having trouble with the float-valves in the carbs.

the pump was installed around 8y ago and the car showed no troubles at the former owners. at least those owners did not recognize anything negative.
the previous owner converted the car to a standard 2500 engine....drove it even long distances to certain meetings...but never rev-ed it, nor drove high speed.....as the engine was consuming oil, a refurbished and slightly tuned 2500 engine was finally installed. the car was driven just 1000miles before selling it to me. due to the running-in period, he never rev-ed it above 4000rpm.

so it was the first time under my ownership, when i really stressed the car and its enigne...and the problem came up.

as the car came with a spare mechanical fuel pump (leftover from the refurbished engine), i temporary installed that pump and the cut-outs were identical. this was misleading me into the direction of the needles.

last weekend i was tidying up the garage and i found a new electric Facet-Pump (the one with the square design) and a Filter-King pressure regulator with fuel-filter
so i thought: why not give it a try and install those parts instead the Hüco pump. i removed the Hüco-Pump, installed the Facet --> test drive-->all fine!!
next day i installed the Filter-King --> all fine!!!

later i inspected the Hüco Pump and found a marking on the pump-body, called "top"..and how was it fitted from the garage 8y ago and no-one recognized it, even 2 former owners? the pump was fitted upside-down!!!

room for speculation left: was the pump tired? or was it due to the wrong mounting-direction?
fact is: problem solved --it was the pump.

[valencia]

It's good to hear that your car is now lively and performing well, if anyone has done a modification previously maybe not a bad place to start the fault diagnosis. If I have a problem with my engine I tend to start by thinking "what did I change from standard spec?"