Hi,

I'm not real familiar with the Merc 350 magnum, although I believe that
it is the fuel injected version of the 5.7L Merc that is in my Maxum.

First thought would be to determine if you have spark during the
time that you are trying to start the boat before it fires. If you
do, then the next thing I would check would be the fuel pressure. The
fuel injection systems require a high working pressure, and any small
leak would cause it to depressurize. Could be the slow starting is
due to fuel pressure coming up.

Another good possibility is that one of your sensors is going flaky, and
giving the ECM bogus info causing it to give the engine the wrong fuel
mixture. Usually a rich mixture will cause the engine to start right
up, but then it won't run very well. A too lean mixture will give you
a hard time starting.

As far as the engine cutting out when you hit a wake... Could be a bunch
of things: Loose connector somewhere, Shift kill switch poorly adjusted,
etc.

After you get it running, can you kill it and easily re-start it? That
would be a big clue that the problem is fuel related. How long does it
have to sit before its hard to restart?

Don W.

Electraglide wrote:
I have a 2002 chaparral signature 240 that I just purchased, the boat
was bought new in Denver. When I try to start the engine I have to
turn it over for several seconds to get the engine started, when I say
several seconds I mean like 15 to 20. I can hold the key and let the
engine turn over about three or four times and let go and it will
crank but I have to use this procedure a dozen time before she'll
fire. After it starts it runs fine it's just a pain to get running.
I live at sea level so I was wondering if maybe the ECM wasn't
adjusting to the change in pressure. I don't have a scanner yet but I
am looking. I just thought maybe someone in the group may have had
this problem and can steer me in the right direction. Oh yes I called
Mercury Marine and one of the tech's told me that the MAPT sensor had
plenty of range to adjust to the change in altitude. I checked the
plugs and they were all very "wet" so I feel like the hard start
problem that I have is the ECM not adjusting to it's new surroundings
and still hasn't leaned out the mixture. The engine has 167 hrs. on
it, runs like a top if I can get it started, it's a mcm 350 magnum mpi
300 hp with bravo lll outdrive. Also while it's running if I hit a
large wake the engine "cuts out" momentarily could this be related to
the hard start problem? Any thoughts or help greatly appreciated.
electraglide
gulf coast