One day when I was leaving UCI on the 178 the bus passed on a stalled 79 whose driver couldn't restart it. Coincidentally the 178 ran into a problem of its own as a mile later it got hit by a car. It was a bad day for OCTA buses all around.
@venom2nd - when a cng bus is low on fuel...that bus will start running funny, misfiring, and jerking. If anything it probably had something to do with the Cummins ECM ( Engine Control Module )
I rode on an LACMTA NABI 40-LFW CNG on Local & Express line 460 to Disneyland. It stalled once on the I-5, where the operator pulled over to the farthest right lane where it stalled. It was restarted after 4 tries in one-minute, where we made it uneventfully to Disneyland.