Am I paranoid or what? 4.3L 2bbl fuel smell, acts flooded when hot, dipstick pops out

[gixxerjim]

Pretty much sum up my questions. When the '92 4.3L Merc 2bbl is shut down hot for a half hour or so, there is a fuel smell. Not strong mind you but just a faint fuel odor that I noticed. Then it needs to be throttled wide open to start when hot, as if flooded. It may start if this is not done, but not immediately on the first couple cranks, so I immediately throttled it and fires right up.

When this is done, it starts and runs perfectly as far as I can tell.

Also, every time I have run the boat (I have owned it just two weeks and been out three times) the dipstick backs out 3/4". Odd, maybe just from waves but don't recall this in our old I/O.

History: 4.3 and outdrive all rebuilt in 2007. Clean, inside and out from looking at motor and drive, checking fluids etc. Has run very well on our three trips, pulls hard, sounds good, though fully loaded only musters about 39 mph/4800rpm with a fairly good condition 17P 3-blade aluminum prop (some say this fine for this boat, others think it should be overrunning).

So am I paranoid or do I maybe have a fuel delivery problem? I noticed the fuel line running to the motor is a very wimpy looking maybe 1/4" OD clear plastic line with very little play in it (cut kind of short to my eye), and no clamp at the carb. Just pushed on. Is this the normal fuel line and arrangement? It seems to me my old '88 3.0L had a steel line to the carb, but I may be wrong on that.

 

[sharkin95]

Re: Am I paranoid or what? 4.3L 2bbl fuel smell, acts flooded when hot, dipstick pops

Wow ...junk all that ...from the tank you need below the deck A1 3/8" id fuel line with a anti siphon valve installed at the tank to a fuel seperator mounted on the engine or somewhere close to the engine from that aluminum 3/8 id fuel line to the electric fuel pump from that to the carburetor all aluminum if possible if not A1 marine fuel line with brass barb outlets..I would have crapped my pants if I had seen that !!!

 

[wellcraft-classic210]

Re: Am I paranoid or what? 4.3L 2bbl fuel smell, acts flooded when hot, dipstick pops

Interesting topic--

The mechanical fuel pumps had a clear Vacuum line running from the pump to the base of the carb as a safety option in case the fuel pump diaghphram ruptures. You should also have a steel line delivering the fuel from the pump through a fuel filter that looks like an oil filter in then to the carb. ( if that is plastic i would be highly concerned & replace it ASAP with steel )

Many of the Mercarbs of that era had a hard start problem after running hard & sitting 5 or more minutes as you described. Apparently the fuel tends to boil in the float bowl and make its way into the intake.

So -- if you can rememeber to run you blower and can live with it -- you would be following a path many others have taken.

As far as a permanent fix;;
The carb should most likely have a phenolic spacer under it and the float setting & needle valve seat is critical. Some have gone to a 4 barrel eldebrock ( which is apparently a modern Carter AFB ).
I have wondered allso about the exhaust pasages from the heads through the intake as many of the intake manifold gasket sets allow for leaving them closed of or knoking out an openening. The heat was mainly for the heat activated automatic chokes & most of the marine carrbs are electric. The heat helps vaporize the fuel so if it could affect some engine performance. I have not run across anyone who has tried it.

The experts here may have added wisdom -- but thats my undersatinding of it for my 1988 boat wth a 2 barrel that's prone to this as a design ussue.