"John H" wrote in message
...

On Tue, 21 May 2013 20:41:39 -0400, Wayne B
wrote:

On Tue, 21 May 2013 02:55:41 -0400, "Eisboch" wrote:



"Rupp0003" wrote in message ...


1989 merc 3.0 starts fine, runs fine for about half an hour at any
speed
or rpm then starts to miss and will eventually stall. Fuel dripping
from
flame arrestor but only once rough running starts. Will sometimes
restart after a few minutes and run ok other times will continue to
run
rough and stall.

Are there any members out there that might have some insight into
what
the problem might be?

--------------------------------------------------------------------


Bad coil. (Goes bad when warm .... ok when cold.)

====

Probably right. I had that problem on one of my old 454s. To make
it worse, some genius decided that the coil should be mounted very
near the exhaust manifold.


The dummies who built my old Proline put the live well right above the
coil, with no sealant. Took
me two coils to figure out where the problem was.

I think Eisboch nailed it. At the price of coils, it's well worth
giving a replacement a try.

John H.

----------------------------------------

Maybe. Educated guess due to similar experience. The fact that the
OP says it runs fine at any speed for about half an hour makes me
think it's probably not carburetor related. Sounds more like
something heats up and fails which is more likely an ignition problem
and the coil (especially if it's older) is suspect.

Had the same thing happen one morning on the old '82 Century. Mrs.E.
and I were taking a ride up to Boston Harbor from Scituate. It was
probably just about in the same timeframe that the engine sputtered
and died, right in the path of one of the Boston to Provincetown high
speed boats that was just getting up on it's hydrofoils. It blew by
us in a rush with it's horn blaring. After sitting dead in the water
for a while the coil cooled off enough to restart the engine and we
limped our way slowly back to Scituate at idle speed.