F150 Stalling At The Dock
by Ron Zastocki, Senior District Service Manager
Article published in the ON BOARD, October 2018 / Volume 8 - Information for the Yamaha Marine Service Professional
A technician and I were working on a fairly new F150 engine that was tied to the dock, and no matter what we did, we could not stop this engine from stalling. We adjusted everything the best we could and made sure all the stats were showing perfect. We added clean and fresh fuel. Still, the engine would stall every four or five shifts, and in some cases, the flywheel would stop or come close to stopping. Before we could conclude why the engine was stalling, the customer arrived early for his appointment and immediately wanted to go for a ride.
Knowing we had everything set correctly, we crossed our fingers and went for a ride. The customer ran the boat a mile out from the dock, then slowed down to an idle. He then began shifting to see if the stalling issue had been fixed. He shifted the unit unmercifully at various forward and reverse speeds, and then engine never stalled. The customer was extremely pleased the stalling issue was corrected.
Here is the conclusion I came to: shifting a unit while it is attached to the dock puts the engine under more load. While underway, the propeller has water coming to the blade, but being tied to the dock adds more load because the blade is pulling water to it. This is a four-cylinder, four-stroke, and two cylinders will fire per revolution. If face with this issue, perform adjustments and run the boat away from the dock to clean out the cylinders. If leaving the dock is a hassle, title the engine up partially and direct some prop was to the surface, this reducing load and the clearing the engine. Either way, the overall purpose is to reduce any additional load on the prop. If the engine doesn't stall after two to three shifts, run the boat in open water and test shifting away from the dock.
NOTE: If the sync-and-link procedure in the service manual is followed correctly and the unit stalls when not moored at the dock, you probably have other issues. These can include a sheared flywheel, poor fuel, partially clogged or failed injector, fouled spark plugs, heavily carboned cylinders, a wrong style propeller, or too large of a prop for the application. These are just a few factors that contribute to stalling. The engine should turn 5800 - 6000 rpm at WOT moderately loaded.