The last few years the '93 750SS has had delays in getting the pop-off to open.
I chalked it up to the stock 70 gm. spring.

I upgraded to the 42 mm Keihin for a better response/no choke and it worked for awhile.

At the end of the last day out on the lake, the pop-off would not open for anything.

I put a 40 gm. spring in the 42, but it's still a no-go. I put the original carb back on and still a no-go. It runs fine otherwise.

Is there a way to check fuel pressure - perhaps by monitoring the fuel return line and pinching it for a few seconds?

Is there any guidelines on what reading I should see on the surge port?