TRACON Controller described a likely MVA infraction when the Data Block of an opposite direction departure failed to acquire and the aircraft was climbing slow because of an engine issue.

Narrative

Aircraft X departed ZZZ; which was on Runway XX procedures; a configuration I have not worked often. Upon departure; Aircraft X did not acquire and was primary only for about 1.5 to 2 miles. The aircraft was now on a heading opposite direction ZZZ1 Runway YY arrivals and unidentified. Once the transponder issue was taken care of; Aircraft X was observed at 900ft and RADAR identified. Using anticipated separation based on standard climbing rates; Aircraft X was issued a turn into a higher MVA that would have been legal based on the 900ft rule. As the aircraft turned and subsequent miles after being established on the new heading; the aircraft was observed making very little progress in the climb. Now headed to an even higher MVA; the 900ft rule was now being violated again. This airmen ended up coming back to ZZZ about 10 minutes later returned because he was having engine troubles and was unable to maintain altitude. Recommendation; to prevent this event from occurring again; before turning the aircraft I will allow more time to observe the climb rate. I will then question the pilot about his climb rate; and asked if he can maintain his own terrain and obstruction clearance. I would also vector back towards a lower MVA. Another thing I could do is turn a slow climbing aircraft on a Southwest heading to allow more time to climb then loop the aircraft back Northbound. I would also recommend a procedure change; an assigned heading of at least a turn to a 200 heading to place the aircraft into a 2000ft/1600ft MVA because the aircraft are only climbing to 2000ft.