MESSAGE TO TECH HELP:

IM WORKING ON A 1986 300 E MERCEDES BENZ AS A STUDENT AT JOHNSON COUNTY COMMUNITY COLLEGE IN OVERLAND PARK, KS. THE VEHICLE IM WORKING ON MAY SIT FOR TWO - THREE DAYS WITHOUT BEING STARTED. WHEN I START IT, IT MAY RUN FOR 10 MINUTES THEN SHUT-OFF. AN HOUR LATER START IT UP IT RUNS OK. IM TRYING TO FIND WHAT THE PROBLEM MAY BE . DO YOU HAVE ANY IDEAS WHAT THE PROBLEM MAY BE ? THE VEHICLE HAS 150,000 MILES ON IT. I JUST PUT A NEW FUEL PUMP ON IT. THE GAS GAUGE HAS BEEN MALFUNCTIONING INCORRECTLY LATELY.