After a couple days of googling and not finding a suitable answer I’l turning to the community. I have a 1970 cougar with a 351C. The engine was rebuilt about 25 years ago and the carb (Holley 750 4bbl) about 4 years ago. On cold starts it runs very rough and I have to play with the manual choke and give it some gas before it idles well enough to put it in gear.
I’ve noticed that the fuel pressure reads 12 PSI with a stock fuel pump which is way too high considering that only 5-7 PSI is recommended. After the car is at operating temp, it runs smooth and accelerates fine. The fuel pressure then drops to a steady 3 PSI.
Thinking that the 12 PSI is pushing the needle off the seat and flooding the carb, I installed a fuel pressure regulator. Cold starts and idling is much better, but not perfect. Fuel pressure reads around 7PSI. After driving it around and letting it warm up, the fuel pressure now reads about 1PSI! How is this thing still running? It didn’t feel like there was fuel starvation under heavy load.
Does this sound like a carb issue and I just need some fine tuning, or is this a symptom of a larger issue (bad fuel pump, wore cam, etc.). I’ve read that some of these liquid filled pressure gauges can be junk so perhaps these are false readings? The gauge is only a few months old.