Hello,
I have a 4.3L Volvo (Chevy) motor in a 1998 Larson ski boat. This motor
has the 'upgraded' 4bbl carb. from the factory. Last year the engine ran
great. I have had it out 4 or 5 times this year and have noticed a problem
that gets worse every time I take it out. During the first trip I noticed
on two occasions, the engine cut-out for a fraction of a second when I
accelerated from a stop. It did this a little more often on the second and
third trip. On the 4th trip out, it started cutting-out completely for a
second or two while cruising. During the 5th and latest trip, it would
cut-out and quit completely. It would take a couple of tries to get it
restarted.
At first it would only cut-out during acceleration, but now it will
cut-out either at idle or during cruising. It will run great until this
happens, and it gives no warning. It will run fine for 10 - 30 minutes
after I launch it before it starts this problem. Once it cuts out for the
first time, it usually keeps happening fairly constantly thereafter, but
runs great until then.
I thought it may have been a problem in the ignition system, so I
replaced the module, distributor cap, and rotor since there was signs of
corrosion on them. The ignition coil looked fine so I left it alone. This
didn't fix the problem though. Someone suggested the fuel filter/water
separator may be clogged so I replaced it with no change. I checked all of
the wiring to make sure nothing was loose. I know that it can go over rough
water just find without cutting off...and will cut-off when idling in calm
water. Therefore, a loose wire doesn't seem like the problem. The problem
is definitely intermittent as I have not felt any decrease in performance.

Any ideas/suggestions will be greatly appreciated!!!

Patrick