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1990 Supra PCM 351 Problems

wetvette92

New member
"Ok, I have been battleing thi

"Ok, I have been battleing this problem for over a year now. The boat will run fine out of the water and idleing around the boat ramp but as soon as we head out of the no wake zone at crusing speed we will go maybe 1/8 mile and the boat starts cutting out and will die, it won't start again for awhile and will eventually start but repeats and progressively gets worse and ends up not running at all. Now heres what I've replaced related or not: coil, ballast resistor, points, condensor,rotor, starter, solenoid, ignition switch, altenator, impellar, battery. Any help with this will be appreciated because I'm stuck. It seems (from what I can tell) to be getting fuel fine. After all this happens the coil usually is pretty hot too."
 
"I'm a '91 Supra owner

"I'm a '91 Supra owner with a 351 Ford PCM with
similar experience. I am not a mechanic, but
was plagued with similar experience for many
months.
What I found was that water was entering my
fuel system at the stern of the boat. Look for
your fuel vent at the outside of the boat at the
very back by the swimstep. It is a black cap sort of piece. Just behind this vent cap on the
inside of the boat is a one-way breathing valve designed to allow air and over-filled fuel to escape and let the gas tank breathe. This valve is designed internally with a floating ball. So,
you drive your boat, the stern dips below the water line, the ball in the valve floats up and stops water from entering your gas tank. In order for this to work properly, the valve must be installed properly. Mine was not. The valve
was turned on its side and instead of the shut-off ball floating up, it was rollig side to side allowing water to enter the gas tank once under
way. I had to puchase a new valve with a shorter
stem in order to install it properly (with stem up at 12:00 o'clock instead of laying over at 3:00 o'clock) and the boat has been fine. Since I had experience removing the rear seat and gas tank and didn't want to do it again, I cut through the fiberglass inside the swim step ski locker right in front of the stern wall allowing
access to the valve screwed on that wall and fiberglassed a patch in later after the repair was made.
Hope this helps. Problem never was ignition, it was fouled fuel.
PS: Love my Supra."
 
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