Engine stops revving abruptly!!

[manxter26]

The car is a 72 911T with a 78 911SC 3.0 with 40IDA3C Webers. It had set for several years so all fuel lines, fuel tank, carbs have been cleaned replaced or rebuilt. The fuel system consists of a Facet fuel pump(rated at 32 gal/hr) in the stock location by the left rear suspension, feeding into a Fram canister style fuel filter in the stock MFI filter location, feeding into PMO bypass regulator with gauge, then returning to the tank. The line returns at the regulator, so there are two lines that dead end at the carbs. My thoughts were that the Fram filter would help stabilize the pulses of the pump and give a smoother flow to the carbs, not sure where that idea came from but it made since at the time. The car is running the stock 78SC ignition system.

So here's the problem. The car drives great and is very smooth, but there have been a couple of times that I have really romped on it. Like 6200rpm shifts. The first time I tried this, I went thru 1st then 2nd then 3rd, and about 4200rpm in 3rd it just stopped pulling and about jerked the car off the road. This has happened 4-5 times, always at about 4200rpm, but sometimes 2nd, 3rd and 4th. There is no backfiring or missing, the engine doesn't quit, it just scares the crap out of me. I'm pretty sure that I am just emptying the carbs, but the fact that it happens at about the same rpm every time makes me wonder if it couldn't be electrical. If I ease into it, I don't seem to notice it until the upper gears. I know the Facet isn't one of the favored pumps but it seems like there is alot of you guys using them. How much fuel, gal/hr are required to keep the Webers happy? Is the Fram filter restricting the fuel to much?

Let me know what you think, I'm open for suggestion.

[T77911S]

other things to think about:

problems with the rev limiter

advance

cross firing of ignition wires

CD unit


coil

dist pickup unit

cracked dist cap

with carbs, i would think not enough fuel would be more of a slow thing, like the feeling of running out of gas. it sounds like you are saying it is a sudden loss of power to make the car jerk.

[manxter26]

I agree with the fuel thing. It doesn't act like its running out of fuel, its very abrupt. I would think most of the electrical things that you mention would cause a miss or a backfire. This is like you just turned the key off, but when I let off the gas or push in the clutch, the engine is still running. This is such a sudden thing, that if it happened in mid corner I'm pretty sure that you would go in butt first. How does the rev limiter work on the 78 SC ignition?