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Fuel smell in cabin after wot.

Helisol

Helisol

New member
First of all I'd like to say that this is the first time I have ever participated in any forum. I find most of the time the contributors just want to hear themselves talk and offer useless advice, but I've read several posts here that were very impressive so here goes.
I have twin 454 Crusaders in my 84 Sea Ray and notice a strong fuel odour in the salon after a day of operating on plane.
It's not raw gas, but rather like a vapour smell.
Inspection around the carbs reveals no evidence of leakage.
Could the seats be allowing fuel to pass, filling the bowl, thereby allowing fuel to drip into the throat?
The engines have 800 hrs. on them and the previous owner appears to have cared for the boat, but I am unaware if the carbs have ever been overhauled.
 
Is this after shutting down that the fuel smell is detectable or while running? Also, any of the odor present went you first get to the boat, after it has been sitting a couple days?
 
Aluminum tanks, smell seems to emanate around the spark arrestor, no sheen on any bilge water.
The smell is after shutting down and not detectable while running and no, there is no odor after it has sat for a few days.
 
How well does that motor HOT restart? Does it crank a while before lighting up, or does it fire right up (as you would expect)?

Jeff
 
My guess is that the fuel is being vaporized by the hot soak condition caused by shutdown, especially if you don't give the engine some "cool down" time before shutting it off.

Best way to verify this is to make some temperature measurements inside the engine compartment while running and after shutdown. The installation manual has the current details; going off memory, the upper limit is 150 deg F. As you can imagine, this is real easy to exceed with a hot engine and no forced ventilation.

You can also experiment with your operating habits...do you give the engines a fast idle period in neutral before shutdown or run the blower when not on plane?
 
I believe that I have been giving the engines some cool down time. Travelling through no wake zones into marinas or looking for a spot to anchor for the night always takes time.
I have also tried running the blowers during those cool down times.
But you know from a troubleshooting stand point I was just thinking as I read your post, maybe I should close the fuel valve and let the engines starve after a cool down.
What do you guys think?
 
in neutral, say at 1500 rpm, isn't the same thing as motoring thru the now wake zones....

closing the valve to the fuel supply may help - there will likely be some fuel in the bowl that may boil if the engine compartment is too hot. that said, the fuel odor should dissipate much faster than when the carb is full fuel. just remember it will take some cranking to refill the fuel bowls - be careful with the starters.
 
Personally, I never shut those blowers off. Five minutes before engine start they're on, and they stay on until the engines are shut off.

Jeff
 
Just remember, the blowers, when installed correctly, serve to remove any fuel vapor that may have entered the engine compartment. Their use (as installed) is nowhere near ideal for removing the heat in that space.
 
Thanks guys I'll definetly try your ideas once the boat goes back in and also investigate the source more thoroughly.
I'll be sure to report my findings.
 
Sir:

Above all, you need to invest in a fuel vapor detector system and install it. EVERY inboard boat should have one. I replaced the bad sensor on ours and the first time we left the slip it went off. Thinking it was merely a "nuisance trip", I nevertheless popped the hatch open to find--gas! Everywhere! (A new fuel pump's metal fitting had cracked, spraying gas like a fire hose!)

Best $150 I ever spent.

Jeff
 
Funny you say that.
On our sea trial after we purchased the boat 2 years ago the broker pointed out that he thought the fuel vapour detector was not working. I never got around to investigating it.
Then at the end of the season last year on our last trip we got into some really rough water coming home and the alarm went off. After lifting the hatches we were unable to determine the reason for the alarm. There were no fumes, no fuel, nothing that we could detect.
You've reminded me that I have something else to troubleshoot.
 
FWIW, the detector (sensor) in the first several generation fume detectors will trigger if sprayed with bilge water. if enough water gets to the sensor, it will fail the sensor, usually so the horn sounds continuously. Those early desins also have a finite life.
 
I recently replaced my sensor, the old one (Fireboy) was 22 years old and it began setting off the alarm for no reason. The unit I replaced it with is a 2 zone unit. I put one sensor in the engine room, and the second sensor in the aft compartment where my generator and fuel tank is located. I know it works because I was spraying the metal parts with corrision X and it set the alarms off. It is also supposed to go off if there is water, but it hasn't gone off when I wash down the compartment. Not sure how much water would set it off...
 
Oh okay it was a continuous alarm. So if it's fumes it's not continuous?
It's also a fireboy I believe.
Aw crap now I feel stupid.
I'll be doing a bunch of reading when I get to the boat this weekend.
 
mine does a beep if the concentration of hydrocarbons gets to a 'caution' point; it goes continuous when it get close to 'explosive'.

bet the manual is on line, just search for it.
 
I had a 1982 sea ray with 454"s and had fuel smell due to carbs dripping fuel into intaks manifolds. I converted to fuel injection and odor went away.
 
Aren't the quadrajets famous for the bowl plugs dripping into the intake manifold and offgassing? Supposedly can be fixed at rebuild with JB weld?
 
Urban Legend in the marine world unless it is a very old 70xxx casting.

BTW, the thread laid dormant for about 18 months...
 
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