The car: 1981 GSL, stockport rebuild by Marvelspeed in Garland about 10k miles ago, Dell'Orto DHLA48 but as far as I can tell NOT an RB modded Dell, RB sidedraft Dell manifold, stock exhaust with a pipe instead of cats. Stock fuel pump, crappy Spectre (Autozone) FPR.

So here's the problem. The 7 idles just fine most of the time, but will occasionally and for no apparent reason simply die as it drops to idle. Most of the time this happens as I am braking for a stop light, but it doesn't seem to matter how hard I am braking, it simply occurs randomly. It will start back up again and idle fine after it dies.

Something which may be related is a bit of a stumble when I move from part throttle to WOT suddenly. This stumble is noticeable in every gear. The stumble is bad enough that if I go from idle to WOT too fast when launching or in neutral, the engine will just roll over and die. I realize stomping the pedal isn't exactly proper launch technique, but it doesn't seem like it should simply die.

My theory is that it's a fuel pressure problem. Either the stock pump can't keep up, the crappy FPR is causing problems, or both. Any thoughts?

 

Firstly, your stock fuel pump is not sufficient to drive that carb, those are barely enough for the stock Nikki. I believe that you have multiple issues so its best to eliminate them one at a time. Get a better pump & fpr,and an inline gauge between the fpr and the carb. Proper and accurate fuel pressure is essential to tuning your carb. Once you get those items then you can start addressing the issues.

If you are dying when you come to a stop I'd have to think that is not a pressure problem, as you are using less fuel then. The stumbling thing is pretty common and can be traced to the carb transferring from the idle circuit to the main circuit. Like I said, get those other items first and then you can start messing with the mixture, jetting, etc. to get that puppy running right!