Reply To: 1956 Johnson 30hp High Speed Tuning

[rhalbert10@outlook.com]

Thanks for the very good info above.  Here is the update from my runs yesterday:

• I cut down the fuel line by 4 1/2 feet – it was way too long in the well anyway and kind of drove me crazy…
• I added some Sea Foam engine cleaner to the gas tank just to rule some gunk in there that may be causing issues.
• Was able to run almost indefinitely at 19-21 MPH and definitely a bit longer at 25 MPH but it still would crap out eventually – especially if I hit wakes hard which is a behavior that I find very strange.
• I had my dad drive and I sat in the back with the motor.  If I occasionally pumped the fuel bulb we never had an issue and could maintain speed.
• That led me to the fuel pump does not have the proper throughput to hang at full throttle. That appears to mirror what you all are saying as well…

As far as replacing the fuel pump (the suggestion above was with the Sierra 18-7351) does that unit truly fit the 30HP motor as when I go search that on the web it mentions 9.9HP or 15HP engines.  Just don’t want to get under powered again.  And is this a fairly simple swap out of what I have already.  Having trouble completely visualizing this one installed.

Thanks again to everyone – this info is invaluable!!

Rich