Fuel Pump relay MAS type failing....?? on 1992 Mercedes-Benz 300TE

When I jump pin 1 and 2 I ghet excellent flow fuel into a
small container for good 30 seconds...
then I install MAS relay (which has fuel pump relay inside)
and only get trickle for 2 seconds...tried used spare....flows good for only 3 seconds....
is it possible both MAS relays defective.......or isthere other possible electrical vudu thing going on ???

Asked by for the 1992 Mercedes-Benz 300TE