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1998 Mercury 225 EFI Rough Idle up 2000 RPM then runs good? Saga continues...

crows

New member
So here is the rest of the story for my port side engine (previously posted Lower Unit stuck in forward, no shifting). This is a 1998 225HP EFI, counter rotator on a Boston Whaler with twin 225 EFI's.

After a general service down in LaMarque, TX of water pumps, steering system, lower unit fluids, fuel & ignition checks and fuel filters, I ran the boat this past Sunday.

The port engine was acting up at low speed. Running rough and vibrating like it was missing. When I powered up, engine seemed to run better after 2000 RPM, all the way up to 5600 RPM. Engine appeared to have good power on the top end, along with the starboard engine, but rough when slowed back to 1000-1500 RPM. However, this was short lived after the lower unit CHUNKED...

Any ideas what is driving the low end rough idle? Fuel or Ignition? Engine fires up great, and idles mostly okay out of water with hose water feed, until engaged with a load.

Ideas for next move are much appreciated.


Crowsnest 1998 Boston Whaler 260 Outrage
 
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