Wayne,

1st: on a 671... no smoke usually means compression is fine. If
compression was bad, you would get smoke on startup until they warm. if
it warms and they still smoke badly... you need a rebuild fast... If it
runs after fuel is shut off or it runs away then you needed a rebuild
last year.

2nd: Do you have Racors? Is the fuel level in the tank ABOVE or BELOW
the injectors? If the answer is YES and BELOW then go buy a Racor
rebuild kit or at least buy the washer that sits over the metal ball.
That washer will disfigure over time causing the ball to not seat and
the fuel will drain back into the tank. Also make sure all other seals,
especially the top seals are in good shape (A rebuild kit comes with all
new seals)


3rd: Is the engine turning over the normal speed? If not, batteries may
be low. A slow turnover will cause an engine to slow start.

4th: DO your exhaust ports have the heat sheilds over them? If not,
you can use a temp gun to find a bad cylinder. If not, you can play with
the fuel rack with the cover off to find a bad cylinder. (Not
recommended unless you know what you are doing or have 6 fingers on your
right hand) BUT AGAIN... no smoke means you probably have 6 good
cylinders.

5th- Spend 90% of your time playing with the inbound fuel system. A few
hints: While the engine is running.. everything PAST the lift pump
(The first pump after the racor) is under PRESSURE. Check this area
first for leaks while the engine is running-higher speed the better.
Everything BEFOre the lift pump is under SUCTION. This is harder to
find because there will be no visible fuel most of the time. (See #2)
You can put some semi-viscous liquid around the seals and see if it is
sucked in but that can be difficult to see. (Spit, clean oil, etc)

Don's waste your money on a compression check ($500 +++) until you
have tried most everything else

Have fun... I am in a similar situation with one of our boats but we
have smoke and 1 bad cylinder.... kind of a smoking gun...

Ed
ed at Estrobel dot com




Wayne.B wrote:
On Tue, 24 Jan 2006 20:34:46 -0500, Larry wrote:


No valves. Intake ports and exhaust ports open as the piston
passes over them near BDC when the blower recharges the air and
blows out the dead gases.


That's what I thought but everyone else says there are exhaust valves
in the head.