This may not be a help, but here is a some insight from my experience. I have a '85 - 60hp 2 stroke. It was dripping gas at the motor from the gas line quick connect after I disconnected the the tank fuel line.
I went out on e-bay and purchased a aftermarket replacement check valve/quick connect fitting.
The aftermarket fitting went in smoothly appeared to worked well, eliminated the drip I was trying to correct, my thoughts great.
Went to the lake, boat started fine, throttled up fine, and then after a short time the motor appeared to starve and die.
If I throttled back it would continue to run just fine at about 1/2 throttle.
I had just thoroughly cleaned the carbs and the motor had run fine prior to changing the quick connect fitting.
The aftermarket fitting was plastic, the original oem fitting was metal, they looked the same, the fuel line connected properly.
Pumping the bulb didn't help. But it was the only think I had changed.
I finally stopped by the marina and purchased the oem parts at four time the price of the aftermarket fitting.
The motor has run fine ever since.
My conclusion was that there was some restriction in the aftermarket part that was not there in the oem version
or the aftermarket part was not the perfect replacement for my particular motor model even though it looked the same from the outside.
Think, what have you changed?