Missfire under load

[Seaduction]

Hi I have a 4.3 V6 mercruiser that only misfires when used for a while it also has petrol fumes getting into the hot water system could this be the same issue

 

[scoflaw]

hot water?

 

[Seaduction]

hot water?

When running the hot water it is milky and smells of petrol

 

[scoflaw]

Unrelated then, start with a complete tune up on your engine, plugs, wires, fuel filter and dis. cap. Check compression when you get the plugs out.

 

[techmitch]

Hi I have a 4.3 V6 mercruiser that only misfires when used for a while it also has petrol fumes getting into the hot water system could this be the same issue

When running the hot water it is milky and smells of petrol

Unrelated then, start with a complete tune up on your engine, plugs, wires, fuel filter and dis. cap. Check compression when you get the plugs out.

Not so fast. It could be cracked head or blown head gasket (causing the misfire) along with a corroded through heat exchanger in the water heater allowing combustion gases into the hot water supply.

 

[scoflaw]

Is this a hot water system heated from the engine? Is the engine AF milky as well?

 

[dtfeld]

Or did someone put fuel in the water tank?

 

[techmitch]

Or did someone put fuel in the water tank?

I always forget about idiocracy.

 

[dtfeld]

I always forget about idiocracy.

Happens all the time…water in gas, gas in diesel etc. Gotta watch what goes in where.

I’m not convinced a miss under load and fuel smell in water are related.

A miss under load could be a bad wire, plug, wires to the wrong plug, ignition timing or even bad gas.

 

[Thornton69]

It was only the "hot water" system mentioned. Is there petrol fumes in the engines cooling system as well?

 

[Seaduction]

Definitely not water in gas tank .......I had a look today only missfire when in gear out of gear it will rev at 3k nicely no problems put it in gear and starts to miss fire

 

[Seaduction]

Is this a hot water system heated from the engine? Is the engine AF milky as well?

Yes hot water heated from engine
Oil in engine is fine

 

[scoflaw]

Not talking water in gas, is the AF in your closed cooled system contaminated? Revving in neutral means nothing

 

[hughespat57]

Hi I have a 4.3 V6 mercruiser that only misfires when used for a while it also has petrol fumes getting into the hot water system could this be the same issue

what we trying to determine is
1 is the engine closed cooled?
Meaning it has a heat exchanger with a radiator type cap this should only have antifreeze in it
If yes
Check the antifreeze for oil contamination
If no
Look behind the boat with the engine running is there any oil slick from the exhaust ?

2. the cabin water heater has a heat exchanger inside it the two liquids should never mix unless the has a crack or corrosion

what year boat

 

[Seaduction]

what we trying to determine is
1 is the engine closed cooled?
Meaning it has a heat exchanger with a radiator type cap this should only have antifreeze in it
If yes
Check the antifreeze for oil contamination
NO RADIATOR CAP
If no
Look behind the boat with the engine running is there any oil slick from the exhaust ? NOT SEEN BUT WILL HAVE A CLOSED LOOK

2. the cabin water heater has a heat exchanger inside it the two liquids should never mix unless the has a crack or corrosion

what year boat

………1997 ……..