Home › Forum › Ask A Member › 1953 Mercury Mark 15 Test Tank Day
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Buccaneer.
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April 29, 2026 at 6:10 pm #317089
I struggled to just get the Merc mounted on the test barrel. Heavy bugger!
Hooked up the newly refurbished Mercury pressure tank, and couldn’t
get it primed up, but it would fire up on fogging oil.One issue, beside the primer pump not pushing gas to the carb, was
that the pressure relief valve was leaking pressure.
I played with that but still could not get the tank to move gas.
I tipped up the motor on the tank, and covered it with plastic with
thoughts of “calling it a day”, when I got the thought of using the OMC
pressure tank.The Merc tank took about 20 squeezes on the primer trigger to get a
half an ounce of gas moved. When I hooked up the OMC tank,
I had gas to the carb in 4 pushes of the primer.
New diaphragm in the Merc tank, so back to the drawing board.The carb inlet fitting is leaking bad where the fitting swivels in
the nut. Is the fitting even supposed to swivel? Tightening the
nut did no good.There’s occasionally a “rattle”, but I’m not sure if it’s from the mag
or rewind.The throttle is not “holding position”. I can’t remember if there’s
a friction adjustment anywhere but I didn’t see anything obvious.
Throttle will go “wide open” while in any gear when motor is off.
Don’t think it’s supposed to do that.Much homework needed tonight before garage time tomorrow!
Video….
https://youtu.be/fq-w6LYU8isPrepare to be boarded!
April 29, 2026 at 8:19 pm #317106Great looking motor.
Bob
1937 Champion D2C Deluxe Lite Twin
1954 Johnson CD-11
1955 Johnson QD-16
1957 Evinrude Fastwin 18
1957 Evinrude 3022
1958 Johnson QD-19
1958 Johnson FD-12
1959 Johnson QD-20
1982 Evinrude 25hp“Every 20 minute job is only a broken bolt away from a 3-day project.”
"Every time you remove a broken or seized bolt an angel gets his wings."April 30, 2026 at 6:09 pm #317184The fuel inlet fitting on the Merc must be worn out, hence leaks.
The tube inside the nut has a slight flare on the end.
I tried to re-flare it tighter with a ball bearing. It stiffened
up slightly, but when the nut is tightened on the carb,
you can still wiggle the fitting slightly.I found a fancy 90 degree swivel fitting on the Net, but for
$36 I said, “no thanks”.I found a “non-swivel” fitting to replace it.
Haven’t run it again yet, but I can’t imagine it’s going to leak.Found out that the set screw on the “Shift Lockout Barrel”
had slipped, allowing shifting at any throttle speed.
Hard to get at with the Allen wrench, but it’s reset.I made an extension for the high-speed needle so
I’ll be able to adjust the carb “on the go” without
trying to hit the slot on the needle with a screwdriver
while bouncing around on the lake.Bought a “Timorn” Tach / Hour Meter last winter and need
to figure out how to use it before I crank up the motor again.
The manual mentions three different desired speed adjustments.Prepare to be boarded!
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