I'm working with a '91 740 turbo 745 13 months ago the previous owner replaced both fuel pumps with new ones. My car is suffering from an intermittent lean
issue, how do I know probably 50 years working on cars. car starts idles just fine
I take it out and drive it hard the issue begins seems to be solved generally by time. i.e. take home put in garage an hour later all is well again until it begins this once more. this episode does not occur every time I drive the car just every 2-3 times. I removed in tank pump to confirm hose is sound & bench tested with 12 Volts I reinstalled in tank pump while filter & inline pump removed turned key on an adequate amount of fuel being pumped out. How do I know it was adequate It appeared sufficient to supply in line pump. I installed new filter & bench tested in line pump with one end stuck in gasoline yep scary it shot a strong stream of gasoline. (BTW) WHEN I REMOVED THE GAS LINE FROM FILTER TO ENGINE A VERY STRONG AMOUNT OF PRESSURE WAS EVIDENT. I was thinking can it be a clogged vent line to gas tank? I'm going to try driving with gas cap loose to eliminate this thought. It seems relay is relaying but I'm going to try jumpering relay to confirm an intermittent relay issue yes or no. if this all fails I'm out of ideas help please. thx, Bill

what is the correct PSI AT ENGINE FOR FUEL DELIVERY?