Narrative:

Shortly after we started a single-engine taxi (#1 gen bus on APU and #2 gen bus running off of the #2 engine); my first officer noticed a strong electrical burning smell. At first I did not smell it but then it became very strong and the smell filled to cockpit. Shortly after this; we had what I will call a partial loss of electrical power. The APU shut down un-powering the #1 gen bus. We also lost additional items. Both IRS went to standby power and; although I appeared to have radios that were working; I could not transmit or talk to the flight attendants in the back. The emergency evacuation lights also came on in the back. I tried to reset the #2 generator by taking it off line and putting it back on line but none of the generator control switches would respond. I could not take the #2 generator off line. The smell of electrical equipment burning was dissipating as we returned to the gate. I had to open the cockpit door to communicate with the flight attendants what was going on. We removed the passengers for the aircraft through the front entry door. We were not able to restore any power to the aircraft until ground power was hooked up. After we received ground power; the aircraft went back to a normal power state except the APU was shut down. It was almost like some relays were stuck and they reset when ground power was attached to the aircraft. Dispatch was called and I spoke to [them] about the situation. Maintenance responded to the aircraft and started to troubleshoot. A logbook entry was made. We were given another aircraft and continued to [destination] without further incident.

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Original NASA ASRS Text

Title: B737-300 flight crew reported noticing strong electrical fumes and electrical system anomalies during taxi. They returned to the gate for maintenance.

Narrative: Shortly after we started a single-engine taxi (#1 gen bus on APU and #2 gen bus running off of the #2 engine); my First Officer noticed a strong electrical burning smell. At first I did not smell it but then it became very strong and the smell filled to cockpit. Shortly after this; we had what I will call a partial loss of electrical power. The APU shut down un-powering the #1 gen bus. We also lost additional items. Both IRS went to standby power and; although I appeared to have radios that were working; I could not transmit or talk to the Flight Attendants in the back. The emergency evacuation lights also came on in the back. I tried to reset the #2 generator by taking it off line and putting it back on line but none of the generator control switches would respond. I could not take the #2 generator off line. The smell of electrical equipment burning was dissipating as we returned to the gate. I had to open the cockpit door to communicate with the Flight Attendants what was going on. We removed the passengers for the aircraft through the front entry door. We were not able to restore any power to the aircraft until ground power was hooked up. After we received ground power; the aircraft went back to a normal power state except the APU was shut down. It was almost like some relays were stuck and they reset when ground power was attached to the aircraft. Dispatch was called and I spoke to [them] about the situation. Maintenance responded to the aircraft and started to troubleshoot. A logbook entry was made. We were given another aircraft and continued to [destination] without further incident.

Data retrieved from NASA's ASRS site and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.