Clean the idle passages again, and leave the new fuel pump in the box. Read the model tag before a jet or a spark plug goes in the cart. The motor is a carbureted 88 hp Johnson or Evinrude on a Whaler. The year is not known. It had been used, the previous owner could start it in the water, and it would not idle. It did not sit for five years. The carbs were cleaned and put back. After a ride, the idle was still bad.
Idle still missing after a carb clean
| Fact on this motor | Next | Not next | Shop |
|---|---|---|---|
| Carbs cleaned, idle still dies | Another pass at the small passages, carbs off | A set of used carbs from a listing | View Carbs cleaned, idle still dies (affiliate) |
| A new fuel pump, uninstalled, old pump not proven bad | Leave it as the spare | Installing it in the same afternoon as the carbs | — |
| Hard, random revs in gear, and the boat still speeds up with rpm | Stop. Find what is opening the throttle | Backing the idle screw out and going again | — |
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The passages a dunk misses
The idle circuit is a small brass jet and a drilled passage beside it. Varnish in that passage leaves the motor able to run on the main circuit and unable to sit at idle. That matches a motor that starts, pulls, and dies as the grip comes back.
Berryman 0117C is the B-12 carb cleaner that Berryman marks VOC compliant in all 50 states. The older 0117 can is not legal to sell for use in Massachusetts, which is where this boat is. Spray the removed carb, and run a fitting wire through the idle jet. A wire larger than the hole enlarges the jet. Start with the smallest wire that passes.
The surge
On a later run this motor idled badly and also surged hard at random, including in gear. The boat still picked up speed as the rpm rose, so the prop hub was not slipping. That surge means something is opening the throttle by itself: a cable, a link, a sticky cam. Unscrewing the idle stop "a bunch," which was the plan on the dock, lowers the stop the plates are supposed to rest on. It does not fix a linkage that has already left the stop.
Stop the motor when it surges under load. A two-stroke that runs away in gear is not a test pass. The idle screw, the spark plugs, and any link-and-sync procedure wait until the tag is read. A plug number from an 88 SPL chart is how the wrong part gets onto a motor whose year nobody has confirmed. Used carburetors from a marketplace listing stay off the boat. The bodies already on it are the ones to finish.