Peter out is an expression that means a fading effort or something that starts off well but eventually dwindles to nothing.
"I rebuilt my engine. There were some extra parts. I was surprised when it started. It ran for a bit but then petered out."
There's a few theories on the origin of this expression. One theory is it comes from the biblical account of the
Apostle Peter and his actions shortly before Jesus's
crucifixion. In the Garden of
Gethsemane Peter was a quick defender of Jesus. He cut off a Roman soldier's ear in defense. However, Peter's efforts in defense of Jesus Peter out. He denied knowing Jesus three time.
The other theory it comes to us from the
Ohio Valley and the actions of a big talking day laborer named Peter Schmidt. This Peter was renowned for talking a big game, making a big show of things on the job for a day or two but then quickly
slacking off.
A more
odious explanation is that it comes from the French word
peter, which means to
fart. So like a, umm, fart, it comes on strong but then dissipates.
Another theory is the use of
saltpeter in mining. Saltpeter was used in blasting caps used by gold-rush miners. The explosives allowed quick access to the richest gold deposits but eventually the gold haul would peter out. This last explanation might be the strongest as the first known use of the phrase was found in reference to gold mining.