Spark plug is black and burnt

[Nagaj54]

I am having issues with starboard motor.
Would not pass 3400 RPM and now dropping to 3000 to 2700 .
What would cause the plugs to look like this?
I changed the plugs and all fuel filters.
I am waiting on wires to install today and test run.
Any other potential issues causing black plugs?

 

[Little Ducky]

Something's up with your fuel system.

Running rich/dumping fuel.

All spark plugs are like that?

 

[Nagaj54]

There is 3 or 4 only that bad.
I changed fuel filters that were pretty bad, but not sure if that will help.

 

[scoflaw]

injectors, if you lose 1 you will lose all 4. Every other 1 in the firing order. 2 bank system

 

[Nagaj54]

Sounds correct!
I get the bad fuel smell and seems to be excess smoke and no power after 3000 RPM.

instead of replace or remove for cleaning, is there a product that actually works without removing them?
I know SeaFoam is a good product but I have 1/2 tank of fuel.

 

[scoflaw]

Fix the problem first or they will just soot up again.

 

[Nagaj54]

injectors, if you lose 1 you will lose all 4. Every other 1 in the firing order. 2 bank system

Makes perfect sense, do they need to be removed and cleaned or replaced or can I use something like SeaFoam?

 

[Nagaj54]

Makes perfect sense, do they need to be removed and cleaned or replaced or can I use something like SeaFoam?

 

[Nagaj54]

The four bad plugs you nailed it, well done.

 

[Nagaj54]

The injectors I’m asking about

 

[scoflaw]

Order up some injectors , when they fail and take out a bank it's an electrical issue not a cleaning. issue.
Plugs will self clean when you get that sorted.

 

[Nagaj54]

Something's up with your fuel system.

Running rich/dumping fuel.

All spark plugs are like that?

I have been working on the boat myself waiting for a mechanic.
My mechanic came out 3 times and found no codes.
I said lets pull the injectors and he is saying he wants to check the crankshaft position sensor?
He invoiced me for $450 bucks already and keeps saying he wants to check other things.
Could the crankshaft position sensor cause to run rich or loss of power after 3000 rpm's?
All i read on this sensor is it makes engine hard to start and makes it stall.

 

[scoflaw]

Crank sensor would set a code. Fuel wouldn't. What cylinders have the fowled plugs?

 

[Espos4]

No codes + running crappy usually is a fuel system problem.

 

[Nagaj54]

Crank sensor would set a code. Fuel wouldn't. What cylinders have the fowled plugs?

I probably miss spoke, plugs not sure if fouled.
The plugs have heavy soot and blackened the ceramic.
Only four plugs look really bad. did not think to match the cyclinder with the bad plug so not sure.
I will run boat and if still no top end pull the injectors.

 

[Jesse Wichelhaus]

Bringing back an old thread here....I have the same conditions (but on all 8 plugs/cylinders) and was wondering if you you could tell me what was your fix? Was it an injector issue or something else? Thank you.

 

[scoflaw]

Probably the cf3 module with a clogged fpr spiking the fuel pressure.

 

[Jesse Wichelhaus]

Checked fuel pressure and is within spec. Replaced FPR and symptoms continue....starts normally but once fired, very very poor throttle response while just holding on to staying lit when lite throttle is given. All 8 plugs are fouled as shown in the picture back in this thread. I Replaced all 8 plugs and all 8 wires....same results. CF3 filters were replaced as well and did not look to be in bad shape. No paint flakes found in filter or FPR screen. Your reply to the original post of...."injectors, if you lose 1 you will lose all 4. Every other 1 in the firing order. 2 bank system".... seems plausible to me here since all 8 plugs are identically fouled indicating bad injector(s) on both banks. All 8 coils were checked as well with no issues found.

 

[scoflaw]

Complete pcm readout would be helpful

 

[Jesse Wichelhaus]

Agreed!....could you describe when you say "injectors, if you lose 1 you will lose all 4. Every other 1 in the firing order. 2 bank system"? I understand the premise of it but just the part of "losing 1 you lose all 4" could you explain a bit?

Thanks