Locating fuel flow/pressure problem with Webers

[jstein]

Brothers,

I think I have a fuel pressure/flow issue.

Here's the skinny-

For as long as I can remember (which, in reality, isn't that long) the fuel pressure gauge in my fuel circuit has registered zero. I always assumed that the thing was just broken - because the car seemed to be running fine.

Except for some weird hesitation/gargling under heavy acceleration - especially right around 3500-4000 RPM.

The thought was to try and go to bigger main jets (oh, did I mention - 79SC with webers - converted by PO).

For various reasons, I haven't gotten to changing the mains yet, but just the other night it occured to me that maybe the problem is further upstream of the carbs - so I began poking around the fuel lines.

The regulation ckt on this car is the PMO type with a clamp on the return line from the manifold (proper term?) right out of the filter. So - fuel comes into the filter from the pump out of the filter into this silver box (again - manifold?) and splits from there to four taps:

1) Left carb
2) Right carb
3) Fuel pressure gauge
4) Return line

There is a clamp, with two bolts on it, on the return line - my understanding is that you clamp down the return line (with the engine running) to the point that the pressure reads ~3.5PSI- and call it "calibrated" (my clamp even has epoxy on it to keep it from backing out - cool!)

Of course, I don't really want to mess with the clamp until I have a working gauge.

Then, on a lark, I was checking the car at idle and decided to pinch off the return line with a (hand) clamp. Guess what? The guage popped right up to 3.5 PSI! Aha! I think. Something must be wrong with the ("PMO") clamp.

I bring the car into work today for a little lunchtime wrenching (and Portillos ) I duplicate the clamp experiment, and low-and-behold, the gauge barely moves!? WTF?

But then I began to think more rationally. What are the chances that a CLAMP is going to fail? It must - MUST - be something else.

*sigh*

So, I would like some opionions...

1) Is it possible my fuel pump is 'kind-of' working - to the point where it spits out a very low pressure, but high enough volume to keep the car running?

2) Maybe my fuel filter is so clogged with crap that there is a giant pressure drop on the thing?

3) Could the gauge really be the problem? (This seems unlikely, as I'm convinced that my hesitation issue is a fuel pressure problem).

Big issue - I'm going out of town this weekend and then on business travel next week. The next DE is next friday, and I want to be ready. What should I try first?

Thanks!