Fuel starvation

[eb61636]

I'm having a strange problem that I cannot seem to figure out and could use some help or more ideas on what it could be.

Here is the situation:

1966 912 with rebuilt motor with 2700 miles on it.
It ran awesome all last year up until about December when I parked it.

The problem began as a mild roughness at revs over 4K RPM.
I also had an intermittent backfie through one of the carbs when I would blip the throttle after coming to a stop.

It was suggested to me (and I agreed) that my fuel pressure could be the problem since it was too high (4.5-5psi at idle).

So I installed an in-line fuel pressure regulator and got the fuel pressure to a dependable 3.5 at an almost constant rate, of course it dips at the first rev, but then catches up.

While in the process of tuning the carbs for the new fuel pressure, the engine started to die and looking at the fuel pressure gauge I had installed indicated that the fuel pressure had dropped to almost 0...it was like.5psi.

I removed and replaced the year old fuel filter and thought i had solved it, but I did not.

A freind suggested it could be points float, so I re-installed the Pertronix unit on the new 050 and tokk the car for a spin...same problem.

Now when I drive the car, it runs like a champ and feels nicely tuned, but when I get on it it goes like ti should for the first half mile, then it runs like it isn't getting any gas...it has no power at all. If I come to stop sign and idle for a minute then take off, it goes again very well and normal for about the first half mile then runs out of gas.

It seems to me that the float bowls are running all the way down out of gas and then not refilling fast enough...but this was happening mildly (all of a sudden) before I installed the fuel pressure regulator!!

I'm thinking that the float bowl settings are off or one of the floats has developed a leak?...neither answer makes sense to me though.

I set everything in these carbs according to the Weber book and Tony Simeon's suggestions.

BTW: The Webers have:

135 mains
55 idles
50 pumps
32 vents
200 airs
F11 emulsions

My timing is 9 BTDC and 33BTDC at 3500+ RPM.

Thanks in advance for any help!

erik.

[h.beard]

Clogged fuel line coming from gas tank, maybe.