twaw
New Member
Hi, I'm really stumped on this one and would appreciate any ideas; it's obviously a potentially dangerous problem. I've had my '93 230 Sundancer since '98, great boat. Last year I started noticing a gas odor in the cabin, usually when tank was more than half full, after running in choppy water. After checking everything visually without finding any obvious issues, I first replaced all the hoses with new hoses (fill and gas supply to engine) and the sender gasket, no change. My mechanic replaced the vent hose, no change. I put gas dye in the fuel, ran it in choppy water and then brought it to my mechanic; the only dye we could find anywhere was one little drop on the engine near the carb. Figuring that the boat was getting on in years anyway, and wanting to avoid an explosion that would ruin my day, I had the tank replaced this spring with a poly tank (sealed tightly with foam). Also, under the flame arrestor, I added a thin cork gasket because there wasn't a gasket there, and I found a little oily residue where it meets the carbs.
At the beginning of the season it seemed to have solved the problem although there was still a very, very faint odor, but as summer wore on and temps reached the 90's the problem seemed to resurface. Now, after running in any conditions, even smooth water, I get the odor, although not nearly as bad as before. I brought it to another mechanic who was also stumped. Here's some more info and a couple of guesses:
-When I notice the gas odor in the cabin, and I check the engine compartment, I think I can trace the same degree of fumes emanating from the carbs. Not the most scientific of tests, but I'm 99% sure that's where it's coming from. We've checked all fittings, everything's tight with no residue or odor.
-All hoses are in great condition since they're practically new. And they're all approved Type A hoses, even the fill line is Type A/SAE J5127.
-We've checked the engine while running; no noticeable spray or leakage from engine.
-Bilge is bone dry.
-Fuel/water separator is tight, and we've checked the metal gas line from that to the carbs.
Here's what I'm guessing: The engine is carbureted, and the gas odor is emanating from the carbs, through the flame arrestor, which is completely porous since it's essentially a screen. I'm thinking this odor is pretty normal for a carbureted engine. And yet, the fuel odor in the cabin is a relatively new problem. So I'm guessing that as the boat has gotten older, and also as a result of putting in the new tank, there are now more cracks allowing air flow into the cabin. There are also 2 spaces, one on each side of the engine compartment, where air flows into the upper sides of the boat, under the deck gunwale. So I have 2 more ideas: have the carbs checked and possibly rebuilt, to ensure there's no abnormal spraying or leaking, and seal off the engine compartment so air doesn't flow into the rest of the boat or cabin.
The only other things I can figure are that the new tank and/or the new vent hose are the culprits; those are the only things I can't really check thoroughly. I wish I could check the connection to the vent itself but I don't know how to do that. But that doesn't seem likely.
Thanks for any ideas!
At the beginning of the season it seemed to have solved the problem although there was still a very, very faint odor, but as summer wore on and temps reached the 90's the problem seemed to resurface. Now, after running in any conditions, even smooth water, I get the odor, although not nearly as bad as before. I brought it to another mechanic who was also stumped. Here's some more info and a couple of guesses:
-When I notice the gas odor in the cabin, and I check the engine compartment, I think I can trace the same degree of fumes emanating from the carbs. Not the most scientific of tests, but I'm 99% sure that's where it's coming from. We've checked all fittings, everything's tight with no residue or odor.
-All hoses are in great condition since they're practically new. And they're all approved Type A hoses, even the fill line is Type A/SAE J5127.
-We've checked the engine while running; no noticeable spray or leakage from engine.
-Bilge is bone dry.
-Fuel/water separator is tight, and we've checked the metal gas line from that to the carbs.
Here's what I'm guessing: The engine is carbureted, and the gas odor is emanating from the carbs, through the flame arrestor, which is completely porous since it's essentially a screen. I'm thinking this odor is pretty normal for a carbureted engine. And yet, the fuel odor in the cabin is a relatively new problem. So I'm guessing that as the boat has gotten older, and also as a result of putting in the new tank, there are now more cracks allowing air flow into the cabin. There are also 2 spaces, one on each side of the engine compartment, where air flows into the upper sides of the boat, under the deck gunwale. So I have 2 more ideas: have the carbs checked and possibly rebuilt, to ensure there's no abnormal spraying or leaking, and seal off the engine compartment so air doesn't flow into the rest of the boat or cabin.
The only other things I can figure are that the new tank and/or the new vent hose are the culprits; those are the only things I can't really check thoroughly. I wish I could check the connection to the vent itself but I don't know how to do that. But that doesn't seem likely.
Thanks for any ideas!
