Most of the piracy along the America's Pacific Coasts were privateers, not piracy, and were limited to the South American Coast. It tended to not be as blood thirsty and prisoners were routinely released. And it was nowhere near as common as it was in the Atlantic, Caribbean/Gulf of Mexico and African coasts.
Keep in mind that Spain had a pretty good strangle hold on Pacific Ocean and guarded the Southern Passage between the Pacific and Atlantic Ocean's pretty heavily between Drake's voyage and into the 1800s. On top of that, the Spanish didn't like to advertise that ships had been lost so they tended to keep things quiet when they were. They routinely surpassed ships logs and maps created by even their own explorers in an attempt to keep the "undiscovered" "Northwest Passage" a secret from other European powers. But even in the Pacific Ocean and with all their military might they still ran huge heavily armed Galleons and trade fleets to discourage piracy.
The other huge problem is logistics. From the 1500s through to the 1750s or so, Spain ruled the Pacific Coast and many the coastal cities there. From about the area of San Francisco northward was "unsettled" land populated only by Indians. If you were a pirate there were few places to go to get supplies or sell the treasure so you had to attempt to cross the Atlantic to China or India, or sail back around through the Southern Passage. There are some rumors of Spanish Pirates working the Pacific Coast, which makes sense as they would have been able to hoist up the Spanish flag before sailing into port to sell their goods.
The most famous privateer was Sir Francis Drake. He was involved in several expeditions as early as 1563 on the African Coast and in the Caribbean. In 1572 he commanded an expedition that successfully raided around Panama in 1572-73, and even captured the Spanish Silver Train at Nombre de Dios. That success led to Elizabeth I sending him to the Spanish owned Pacific Coast and in 1578 he captured a Spanish ship near Lima, and then chased down and captured the treasure ship Cacafuego. From there his travels are murky, speculation is that he may have sailed as far north as 55 degrees Latitude before turning around due to the cold weather. That would have put him somewhere about the Alaska Peninsula. He definitely claimed land for England. The exact location he did so is still unknown but today is generally accepted as being Drake's Bay in California. He might have even planted a colony there, an fact that is supported by how many less men he had later on. But the English falsified Log books and maps to keep Spanish spies from getting them. And all of them from this expedition were lost in a fire in 1698 at Whitehall palace.
From there out most piracy was at the hands of Privateers actively challenging Spain's military might and supporting various South American countries in their attempts at independence from Spain. In the late 1700s England was directly challenging Spanish control of Pacific Coast between Northern California and Alaska. The Russians were pushing down the Alaska coast, and Spain was still dealing with rebellions through out South America which had severely sapped their military might in the previous centuries. A lot of these privateers were working incognito to dodge Spanish Spies in Europe, and again records were still routinely falsified so concrete evidence is hard to find.
The Spanish pushed back at these incursions. In 1789 the Nootka Incident happened after Esteban José Martínez seized two British and two American ships in order to strengthen Spanish Claims on Nootka Sound. The ships were later returned, and a treaty between America, Britain, and Spain established a trading zone that all three countries violated years later. Two of the ships involved in this incident (but not seized,) are still well known. One was the Columbia Ridiviva, of which the Columbia River was named after. The second is the Lady Washington, who's replica is a well known tall ship used in the Pirate of the Caribbean Movies.
But....
There are also tantalizing Native American legends all up and down the Pacific Coast that tell tales of what can only be ship battles and ship wrecks. Stories of huge "war canoes" crewed with light skinned men and creating clouds from their decks are a common tale. Men landing on beaches, killing captives and then burying them and heavy chests on the beach. Early explorers running across extremely fair or dark skinned Natives who must have taken ship wrecked crews into their tribes, Chiefs of tribes who are of obvious African decent, and even an occasional gold or silver trinket. Many of these legends still fuel rumors of pirate treasure, one of the most famous being of a location called "Neahkahnie Mountain." Here is a copy of the legend I picked up many years ago for those who want a flavor of the tale. I personally know people who still travel here after every major storm with metal detectors and shovels.
It doesn't help that for many decades huge slabs of beeswax were found washed up on shore nearby directly fueling further speculation of treasure.
There are enough tales that I find it hard to believe that a portion of them aren't true, even accounting for people stretching the truth.
Another tale surrounds Iron Jim Sallow, who was said to have buried treasure somewhere around what would become Seattle. But any information about him is of the same, rumors and uncertain stories with no evidence to back them up. In fact I can not find a single primary source for him, and suspect he may be a creation of one of the local "Pirate" groups that put on shows throughout the summer.