RPTR LOSES ALTIMETER AND VERT SPD IN IMC AND OVERSHOOTS ASSIGNED ALT BY 1300 FT.

Narrative

AFTER TKOF AND ENTERING THE CLOUDS; THE AIRSPD BEGAN TO BLEED OFF QUICKLY. AFTER CHKING THE OTHER INSTS; THE ALT WAS STEADY AT 1900 FT MSL AND THE VSI AT '0' BUT THE PWR WAS AT CLB AND THE ATTITUDE INDICATOR WAS SHOWING PITCH UP. I CHKED THE COPLT INSTS AND THEY SHOWED THE SAME THING. GEAR AND FLAPS WERE RETRACTED AND THE ACFT SHOWED NO SIGNS OF STALLING. I HAD ALREADY TURNED ON BOTH PITOT HEATS AND THE TEMP WAS 48 DEGS F; SO ICE WAS NO FACTOR. I CONTINUED THE CLB DUE TO BEING IMC AND OBSTACLES. AT THIS POINT I REACHED FOR THE ALTERNATE STATIC SOURCE AND TURNED IT ON. THIS CAUSED THE ALTIMETER TO JUMP TO 4300 FT MSL. I HAD BEEN ASSIGNED 3000 FT MSL AND 4000 FT MSL 10 MINS AFTER DEP; BUT HAD NOT RECEIVED CLRNC TO 4000 FT. THE HDG WAS 170 DEGS. 10 MINS HAD NOT GONE BY SINCE DEP. DEP CTL ASKED MY ALT A COUPLE OF TIMES AND I TOLD THEM THAT IT SHOWED 1900 FT THE FIRST TIME AND THEY SAID IT CHKED. WHEN THEY ASKED THE SECOND TIME WAS JUST AFTER I OPENED THE ALTERNATE STATIC SOURCE. 4300 FT CHKED WITH THE MODE C AND I WAS TOLD TO MAINTAIN 4000 FT; WHICH I DID. AFTER SOME TIME ENRTE; I CLOSED THE ALTERNATE STATIC SOURCE AND THE PRIMARY SOURCE WAS FINE. UPON LNDG AT MY DEST; I CHKED THE STATIC PORTS AND FOUND EVIDENCE OF TAPE OVER THE PORTS. IT WAS PUT THERE DURING CLEANING TO KEEP THEM CLR; BUT SOMEONE FORGOT TO REMOVE THE TAPE; AND I FAILED TO SEE IT ON MY PREFLT; PARTLY DUE TO DOING IT IN THE DARK AND THE TAPE WAS RED -- THE SAME COLOR RED AS THE ACFT STRIPE THAT RUNS ACROSS THE PORT. THE PREFLT WAS OBVIOUSLY NOT THOROUGH ENOUGH AND SHOULD HAVE BEEN DONE WITH A FLASHLIGHT. THE ALTERNATE STATIC SOURCE SHOULD HAVE BEEN OPENED AT THE SAME TIME THE PITOT HEAT WAS TURNED ON. THAT WOULD HAVE STOPPED THE ALT INCURSION.