Gas smell at WOT

All of the responses center around the WOT issue, haven't seen anyone comment on the gas smell. I would think that ta break in the plug wires and gas vapors would not be a good combination. Am I missing something related to the gas smell - just trying to understand.
 
Captn TJ said:
All of the responses center around the WOT issue, haven't seen anyone comment on the gas smell. I would think that ta break in the plug wires and gas vapors would not be a good combination. Am I missing something related to the gas smell - just trying to understand.
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most likely the gas fumes are un-burnt fuel that is being exhausted from the engine and surfacing up from the underwater exhaust....but you are correct that gas fumes in the engine room and the possibility of an arching plug wire is a very scary scenario....

cliff
 
PlayDate said:
Short of having an 8 lead oscilloscope wired to the engine with someone watching it as you run the boat.....looking at the spark plugs is your best path to find a bad plug or wire.

Depending on the effort you want to put in and what your time is worth to you.....sometimes it is far easier to replace the plugs and wires and just eliminate the problem or the possibility of a problem.

One of your current wires could have been compromised and it really isn't practical to run the boat at WOT and watch the plug wires. Oftentimes plug wires get cooked from a minor exhaust leak and then short out at high rpms. The miss is happening under load at high rpms which makes replacing the plugs and wires as the most sensible approach. You can always hang on to the old plugs and wires if they aren't the source of the problem.

Make sure the plugs are gapped correctly and the new boots are seated.
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Plugs were just replaced at my regular 100 hr service. Not long ago. Boat was running fine until now. Could be a plug wire. I guess I need to check pressure at the rail. I'll need the mercruiser tech for that I don't have the equipment.
 
CliffA said:
most likely the gas fumes are un-burnt fuel that is being exhausted from the engine and surfacing up from the underwater exhaust....but you are correct that gas fumes in the engine room and the possibility of an arching plug wire is a very scary scenario....

cliff
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Gas is coming from exhaust. Otherwise I wouldn't be here.
 
MikeBravo said:
Plugs were just replaced at my regular 100 hr service. Not long ago. Boat was running fine until now. Could be a plug wire. I guess I need to check pressure at the rail. I'll need the mercruiser tech for that I don't have the equipment.
Click to expand...

i would start with new plug wires....if the original wires are still being used they are long past due for being changed....then move to the fuel rail pressure if new wires don't help....

cliff
 
CliffA said:
i would start with new plug wires....it the original wires are still being used they are long past due for being changed....then move to the fuel rail pressure if new wires don't help....

cliff
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Wires are 3yo, but you never know in the boat engine world.
 
MikeBravo said:
Wires are 3yo, but you never know in the boat engine world.
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yeah, 3 yrs is a short life for wires but like you said you never know....

good luck...
cliff
 
scoflaw said:
Simple stuff, unscrew the plastic cap on your fuel rail and thumb screw the gauge line onto it.
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Well I can do that, just couldn't believe it was that easy, cause nothing else is. What psi am I looking for? Thanks
 
Besides wires being the culprit when was the last time risers and gaskets were replaced or inspected?
Had the same problem last summer.
Wound up to be bad valves on 2 cylinders due to a leaky riser gasket.
I would pull the plugs first and inspect for rust or fouled with unburnt fuel and go from there.
This will help you pinpoint the cylinders that aren't firing.
Then go from there.
 
cfd95 said:
Besides wires being the culprit when was the last time risers and gaskets were replaced or inspected?
Had the same problem last summer.
Wound up to be bad valves on 2 cylinders due to a leaky riser gasket.
I would pull the plugs first and inspect for rust or fouled with unburnt fuel and go from there.
This will help you pinpoint the cylinders that aren't firing.
Then go from there.
Click to expand...
Just had 100 hr service and all new manis and risers done at the end of last year.
 
spikedaddy99 said:
My 07 320 didn't have the CF3 modules.
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Are you sure? If it didn't.....I'm curious what fuel pumps were on it.

I believe your boat shipped with:
#864650A05 Cool Fuel Module Gen III

001.jpg
 
Yeah, I'm sure as I can be. I asked Sea Ray when that issue reared its ugly head. My boat was not equipped with CF3 according to them. M
 
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