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1973 Evinrude 18 HP Fastwin- bogs when Running WOT in Forward. Runs consistent, just no power

M

muddywatercustoms

New member
I am looking for some advice on a 1973 Evinrude Fastwin 18 HP (Model 18304) that is still lacking power in forward gear.

Here's what I've done so far:

  • Rebuilt and cleaned the carburetor thoroughly. Made sure high speed jet was clear
  • Set the float to factory specification.
  • Installed fresh 50:1 fuel mix.
  • Checked compression, which is approximately 100 PSI on the top cylinder and 110 PSI on the bottom cylinder.
  • Replaced the propeller with a known good prop.
  • Changed the lower unit gear oil.
  • Checked the ignition system and confirmed both cylinders have spark.
  • Inspected the shift linkage and adjusted it to ensure it shifts into forward, neutral, and reverse.
  • Rebuilt the fuel pump and used a fuel pump that I knew worked from one of my other motors
  • I am buying a brand OEM new fuel pump to try
  • Cleaned and set points to .020
  • Ohm tested ignition coils- they tested to spec.
The engine does leak water from the bolt holes on the manifold cover on the side of the engine and thermostat. Not much but you can see water dripping. Could water be getting into the cylinders?

The engine starts easily and idles well. It revs freely in neutral, but when I put it into forward gear and try to accelerate, it bogs down and won't produce full power. It almost feels like it's isn't fully engaging forward gear or is being held back somehow. Reverse seems to have much better thrust than forward.

Has anyone run into this on a 1973 Fastwin? Could this be a clutch dog, forward gear, shift linkage adjustment, ignition timing, or something else that I'm overlooking? The customer changed the ignition coils, condensers, and points. I didn't test the condensers. Any suggestions on what to check next would be greatly appreciated
 
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