We are assuming you are SURE your don't have a diry (clogged) carb or carbs.
OK?

First have someone crank the boat and do a static spark test. If all 6 spark
then your low speed stator winding is OK and (barring a thermal
intermittant) so are your switchboxes, coils and trigger.

Now while on the water try to determine what cylinders are not firing at
speed using an inductive timing light as a test tool. If they are all
firing - back to the fuel system you go.

If some are not firing at speed - suspect the high speed winding in the
stator and/or a thermal intermittant in a switchbox or coil. This will be
hard to track down.

Your motor uses Alternator Discharge Ignition (ADI). You need to 1st ohm
out the stator to see if it meets specs, if not replace it. (and hope that's
the end)

Then ohm out all the little ignition coils seperately to make sure they are
all good (at least when cold)

From there try to find it by swapping - you get identical 6 coils and 2
identical switchboxes. Try to swap stuff around to see if the problem
follows any one part.

-W








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PLEASE NOTE: Email address change from to

"Bob La Londe" wrote in message
...
Trouble shooting Mercury 1882 150 V-8

Sounds like it isn't running on all cylinders, and power loss problem is
getting worse.

I check all my connections at the battery. I cut off all the battery
connectors and soldered on new replacement ring terminals (+ & -) to make
sure I wasn't having any bad ground issues there.

It has new plugs, I did a compression check per the manual and I got
130-135
psi on all cylinders 6 cylinders.

When I first noticed the problem it would lose power going down the lake.
Now it sounds more like it is running most of the time on less than normal
cylinders and occassionally starts firing on the rest for a few seconds.

I didn't see a coil test procedure in my service manual. Would that be
the
next step? Or how how the control boxes? I believe it has the flywheel
alternator ignition setup as described in my manula, but I have not pulled
the flywheel to look.

My fuel tanks are below deck and very difficult remove, or I would flush
them out to make sure there is no water. I have new fuel line from the
tank
to the motor. I am just running on one tank for now until I get this
figured out. I did order a water seperator for it which will arrive
wednesday. I just don't feel like that is the problem since it has gotten
progressively worse, and I have run a couple tanks of gas through it.

It feels like ignition to me.

What do I check next.


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Bob La Londe
Yuma, Az
http://yumabassman.4t.com