1989 mercruiser 3.0 stalling after 30 min

[Rupp0003]

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?




--
Rupp0003

[Eisboch]

"Rupp0003" wrote in message news:Rupp0003...@boatbanter.com...

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

[*e#c]

www.marineengine.com

Its free, and you wont have to put up with any of the fucktards in
here.

[Earl]

Yup. Same symptom as a bad stator on an outboard.

[Wayne B]

====

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.

[Hank©]

The dripping fuel makes me think needle and seat or heavy float.

[Hank©]

On 5/21/2013 11:37 PM, gfre...@aol.com wrote:

> I had that problem on an old Corvette (bad float) and it was fine if
> you didn't slow down.
>
> The tie breaker is to just check the spark when it is not starting.
> One of those enclosed gap testers is safer on a boat than the old
> screwdriver method. That is particularly true if you have gas leaking
> around/
>

Here's another one. Starts up and runs fine for a few minutes after
putting a load on. Moisture on or under the metal baseplate vaporizes
and causes crossfiring at the distributor cap.

[John H]

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.
--

Hope you're having a great day!

[Eisboch]

"John H" wrote in message
news:cchpp8t3m67o77n76...@4ax.com...

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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.

[John H]

Both times mine went bad out in the middle of Chesapeake Bay. Boat started and ran fine - and then
just seemed to bog down and die. That $100/year tow boat insurance was a good investment.

[Hank©]

I wouldn't put money on any of the suggested diagnosis, including mine,
but it would be worth checking out all of them. Most of the coil
overheating problems show visual signs like bulging or oil under the
high tension lead. Carrying a spare would be good insurance.

[Wayne B]

On Wed, 22 May 2013 11:46:18 -0400, Hank� <han...@socialworker.net>
wrote:

>I wouldn't put money on any of the suggested diagnosis, including mine,
>but it would be worth checking out all of them. Most of the coil
>overheating problems show visual signs like bulging or oil under the
>high tension lead. Carrying a spare would be good insurance.

======

The intermittent coil on my old 454 showed no external symptoms at
all. The engine had failed several times previously after it had been
run for a while but on the last occasion I was able to prove that
there was no spark even though the coil primary showed that the
voltage was being properly interrupted.

[Eisboch]

"HankŠ" wrote in message
news:519ce859$0$64463$c3e8da3$5e5e...@news.astraweb.com...

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

You're right of course but the OP's description of how the engine was
acting sound VERY familiar. I was having the symptoms for a week or
two (ran ok cold, started getting rough when warmed up and was very
evident when I tried to push that tank of a boat up on a plane after
being warmed up. I think you were still around here after the Boston
Harbor experience. When it died that time, it blew the high tension
wire right out of it's seat and indeed, there was oil on the coil.
But, after it cooled down for a while, it worked enough to putt-putt
back to Scituate. New coil fixed *that* problem and we moved onto
the next one.
That boat should have been retired from service years before. :-)

[True North]

All this is familiar to me as I had similar problems with the 25 hp Johnson on the Princecraft Yukon.
Screws had worked loose and tore up the stator.
Since I wasn't using it for charging, I had the service tech remove the bad parts and the outboard worked perfectly until I traded the boat in a year ago.

[Hank©]

On 5/22/2013 5:20 PM, Eisboch wrote:
>
>
> "Hank�" wrote in message

He had a symptom that you didn't have.

Ask Harry if he went to the Navy Seal museum just down the street from
the Disney resort he stayed at. They had some pretty interesting old
boats on display.

[Eisboch]

"HankŠ" wrote in message
news:519d4670$0$39083$c3e8da3$dbd...@news.astraweb.com...

On 5/22/2013 5:20 PM, Eisboch wrote:
>
>

> "HankŠ" wrote in message

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

You mean gas in the flame arrester? I don't remember it being like
that but I *do* remember smelling gas due to the carb becoming flooded
after several attempts to start it without success. That was before
realizing the high tension wire had blown off the coil.

[N.L. Eckert]

I had the same problem with my '88 OMC Cobra, I changed the coil &
condenser, problem solved, has been fine ever since.

Happy boating, Norm