mk 2 or mk 1 fuel pressure

[Spike]

A few months ago i asked about fuel pressure on a mk2, eventually sorted found the mk 2 fuel pressure to be 3.5 bar, and the mk 1 should be 4.0 bar, my own fuel pressure was 46psi (mk2) , about 3.1 bar so way down, have since repaired this back to 50 psi which is closer and got a definite boost in midrange power. i have now made a 4.0 bar regulator to fit in the std position in the tank and am looking to fit this in the near future, has anyone got any comments on this? i will do it anyway but would like to put it to open disscusion first, also thinking about a pump upgrade, but want to stick with the in tank pump assembly, again any comments, does anyone think there will be any merit in this? i think the car is running weak at the top end and do not think the standard pump is up to the job anyway. bosch said the pump is rated at 380 kpa (3.8 bar) at 90 litres an hour, is this enough? yes i realise its std fitment but when did any manufacturer build to spec, more like price.
i will await comments.

 

[Spike]

POSSIBLY THE PUMP WAS SUSPECT, I BUILT A TEST RIG THAT ALLOWS YOU TO TEST THE PUMP IN THE CAR BUT AWAY FROM ECU CONTROL, PUMP PRESSURE WAS DOWN TO 46PSI, SHOULD BE 51 ISH, BUT WHEN THE OUTPUT WAS CLAMPED THE PUMP ONLY MADE 70 PSI BEFORE GOING INTO A SPASM, FITTED A VECTRA PUMP AND DIFFERENT REGULATOR AND NOW THE PUMP UNREGULATED MAKES 88 PSI, WITH 50 REGULATED, CAR FEELS MUCH STRONGER BUT LAMBDA READING AT TOP END PULLING HARD STILL READS ON THE WEAK SIDE (NOT WILDLY), MAYBE NEEDS MORE PRESSURE..........OR A WALBRO PUMP!
IF YOU DO THE RULE OF THUMB FOR FUEL DELIVERY YOU NEED 0.12 GALLONS PER HORSEPOWER THIS EQUALLS 138 LITRES PER HOUR, WELL BEYOND THE STANDARD PUMP OR THE VECTRA PUMP BUT WITHIN THE SPEC OF YOUR WALBRO.......