hi Glenn
If you smell gas fumes then look for gas leak. A leak could be the fuel
tank, or a fuel line, gas tank, or fuel pump. It could be that the screws
that hold the carburetor together have become loose. Try checking tightness
of carburetor screws with screwdriver checking each one (top of carb might
have 6 screws, 4 for accelerator pump on side of carb). Check the fuel
filter if it is an inline filter for loose connection on the hose, if its a
plastic inline filter check for cracks. Inside the carburetor there is a
float bowl vent. If the float bowl overflows then gas can pour out of the
vent and be a hazard. A stuck inlet needle or a pice of dirt between the
inlet needle and the inlet needle seat can cause fuel to overflow. Wires can
last for years. A common test for wires is to examine the wires is by
bending the wire across your finger and looking for cracks in the
insulation, if it shows cracks then replace. If the rubber insulation is
still pliable then they're usually still good. Wires that touch each other
can spark between each other causing engine misfire, poor performance, and
be an ignition source in engine compartments. There are ignition wire
spacers to prevent wires from arching they can be bought at an auto ports
store. Due to the fact that you have electronic ignition the plugs probably
burn clean. Removing the plugs for inspection is usually the only way to see
if they are still good. Plugs can be cleaned and re-used, but on the water
new plugs are most reliable.
If your engine is running rough, and you suspect some fuel connection. The
carburetor's gaskets keep the fuel inside and vacuum from sucking air into
the carburetor. If your carb's gaskets are loose then it is possible your
getting a vacuum leak and poor performance.
I'm not a marine mechanic but have worked on my cars for over 20 years and
rebuilt about 6 carburetors. I had the float bowl over flow problem. Loose
screws on the carb a year later problem where I seemed to smell gas vapors.
After tightening the screws again no vapor smells.
Marine carburetors are different than automobile carburetors.
These are some of the benefits of a marine carb:
Spring loaded needle/seat
Internally vented fuel bowl
Sealed accelerator pump shaft
I don't know that these will prevent you from smelling fuel vapors. But
failure of any fuel system can cause a leak.
If you don't know what to do or the tools or experience then a mechanic can
be worth the money.
If you break down on the water or blow your boat up, a mechanic can save you
more than your money spent.
Greg

"Glenn Deneweth" wrote in message
...
I should mention there's no performance issues....Just a rough idle and
strong gas smell...


"Glenn Deneweth" wrote in message
...
I have a 230hp 305, with a Mercruiser Alpha 1 (1986) and this year when
I
run the engine there are a strong smell of gas fumes, the engine is
running
rich. It also runs a little rough. Would turning the mixture screw fix
both of these issues? I had the carb rebuilt 2 years ago, and tuned up
the
engine the same time. It's not running that rough, and but rougher than
last year. How long do spark plugs and wire last? I also have
electronic
ignition if that matters.

Thanks,

Glenn