Commercial Fixed Wing
Flight Crew Air Transport Pilot (ATP); Flight Crew Instrument; Flight Crew Multiengine
Aircraft Equipment Problem Less Severe; Deviation / Discrepancy - Procedural Published Material / Policy; Deviation / Discrepancy - Procedural Maintenance
General Maintenance Action
Aircraft; Company Policy; Environment - Non Weather Related; Procedure
We planned 26K Bleeds Off Takeoff due to Right Pack Inop and per MEL we applied Engine Bleed Off Takeoff or Landing with the APU Operating procedure.  Cleared for takeoff on XXR. At 40% N1 CA TOGA. Both Engines advanced. Engine #2 achieved takeoff thrust of 100.8 N1. Engine #1 stagnated at 85.0 N1. Auto-throttles were on. I pushed on the #1 throttle lever to get a response; but engine stayed stagnated. I was not sure if it was an engine failure or bird strike; so I commanded PF to Reject. We Rejected below 80 knots. Announced Reject with Tower and they directed us to exit first available taxiway. We decided since we were not sure of the nature of the problem; it would be prudent to taxi back to gate and let maintenance troubleshoot the problem.A cascading effect of maintenance issues:  During pre-flight the ground crew pulled the external power without our concurrence which caused a power interruption. Had to rebuild/recover several pre-flight items. Five minutes prior to pushback right PACK light illuminated. Could not reset. Maintenance MELed right pack. During pushback/engine start we could not get N2 rotation on #2 engine with Engine Start switch in GND and Start Valve Open light illuminated. Isolation Valve switch was in the Open position. We made several attempts; but each time we moved the Engine Start switch to GND the Isolation Valve would close; and we would lose right duct pressure. We decided to return to the gate via tug and made a logbook write-up. Maintenance fixed the problem and we pushed off the gate for a second time. The low speed reject was the subsequent event.First; more vigilance/coordination from ground crew prior to pulling external power. Second; local ZZZ maintenance mentioned the plane had been sitting idle for more than 60 days. I cannot verify this information. Maybe more Maintenance pre-flight or systems tests if aircraft has been sitting idle for an extended period?
Air Carrier Captain reported a rejected takeoff due to mechanical issues with an aircraft that had been sitting for a couple of months.