I had this same problem on a 5.0 L Merc, that turned out to be a barely
visibly cracked ceramic neck of the $11 ignition coil !!! changes in heat
and humidity caused it to occur intermittentantly b/c of
expansion/contraction.

Another time this happened, it was because of a bad Sensor assembly - See
Mercruiser Service Bulletin/recall on this.

b-


"Scott Shirley" wrote in message
news:JuCUa.154503$Ph3.18704@sccrnsc04...
I went out to start the boat this morning before making the drive to the
lake...it turned over a few times and never fired (normal when it hasn't
been run in a few weeks). When I turned the key again, I hear a single
click
from somewhere near the rear of the boat and the engine would turn over.
Tried again a few more times...nothing. I replaced the battery a few weeks
ago, so I know there is plenty of juice back there. I tried the old trick
of
tapping the starter (this is an inboard/outboard Mercruiser 5.7L). Tried
turning the key again, and voila...it turns over. Waited a few
seconds...and
again...no dice, hear a single click when the key is turned to start. I am
not too crazy about getting stranded in the water, so I called around to
get
some prices on starters. OUCH...$278.00 for a new one seems to be the
standard price at all the marine parts places here in Dallas. One person
that I spoke with at the parts store recommended hooking up a test light
to
the solenoid to see if I was getting juice across the relay before sinking
$278.00 in a part that can't be returned if it didn't fiz the problem. The
crappy part is....I got home this afternoon and can't replicate the
problem.

My thoughts are that when a starter goes bad, the problem might be
intermitent for awhile. I have yet to see a solenoid/relay exhibit this
intermittent type of behavior. Has anyone ever heard of a solenoid/relay
that is going bad do this or do they just go caput and not work at all
once
they go "bad" ? I'd like to get the problem (whatver it may be) corrected
before heading to the water again. Should I just sink the $278.00 into the
starter and be done with it?