spark plugs

Jason calleja · 20 October 2012, 15:52

Hi all i have to ask you if these pictures that i have attached of my mercury 60 hp EFI 4 stroke 2010 model spark plugs have the correct burn sign. I am thinking that it is running rich but the black on the plugs it is not carbon as if i try to wire brush it it does not go away

Turbodiesel · 21 October 2012, 08:16

Looks normal to me!

Peter_C · 21 October 2012, 21:38

Looks good to me too!

mick · 21 October 2012, 21:53

They look ok better than some I have just replaced check the gap while you have them out

Jason calleja · 22 October 2012, 16:28

These plugs are champion and they have about 5 working hrs on them and they are the oem. Do you think that if i try another brand will work better as i am not convinced that they are doing the correct burn. What do you think?

captnjack · 22 October 2012, 16:32

Quote:

Originally Posted by Jason calleja

These plugs are champion and they have about 5 working hrs on them and they are the oem. Do you think that if i try another brand will work better as i am not convinced that they are doing the correct burn. What do you think?

So despite all advice here to the contrary, what makes you say they aren't working right?

They look exceptionally normal to me. I wouldn't switch plugs, since whatever you switch to will be either too hot or too cool - since those are the correct plugs and they look perfectly normal.

Jason calleja · 22 October 2012, 17:30

I may think that they are not doing the right burn because when i am rinsing the motor in the water thank sometimes i hear a little missing. Or maybe i am getting crazy on it. I will take your advice and keep them. Thanks

captnjack · 22 October 2012, 18:02

Do you have a video (with sound) of this misfire?
Do all the plugs look like that? Or are any of them different?

If one of them is different, its potentially a bad plug or bad wire which is the cause of your misfire. However its quite likely to be unrelated to your plugs at all and something competely different - like an injector, fuel pump, or water in fuel issue.

Changing to a different non-spec plug can really mess up your engine fast, so unless you know these are the problem look elsewhere.

Nos4r2 · 22 October 2012, 18:48

The colour is fine. Change them if you're worried, but don't mess with the spec.

Isn't your engine still under warranty? If it is, don't mess, make them fix it!

Jason calleja · 22 October 2012, 19:18

No i don’t have a video of it and yes all plugs are the same and i don’t think there is any problem with the injectors as it is still a brand new motor with 25hrs on it and fuel line was replaced new 6 weeks ago with all new filters including water filter separator too.
I have also added quick store to the fuel. Could it be the fuel treatment that causing it?

doggypaddle · 22 October 2012, 19:32

Wire brushing them isn't a good idea. Metallic deposits on the insulator ceramic wont help the insulation properties at all

Jason calleja · 22 October 2012, 19:36

I will replace them again as i have wire brushed them

captnjack · 22 October 2012, 20:31

Quote:

Originally Posted by Jason calleja

No i don’t have a video of it and yes all plugs are the same and i don’t think there is any problem with the injectors as it is still a brand new motor with 25hrs on it and fuel line was replaced new 6 weeks ago with all new filters including water filter separator too.
I have also added quick store to the fuel. Could it be the fuel treatment that causing it?

I don't think you have a misfire. Its possible the timing is a bit off, I believe that's on the 25hr service checklist.

yam man · 22 October 2012, 20:56

When working for a merc dealer we had a 60hp 4 stroke come in with 5 hours on it .The customer was complaining of a slight misfire now and then couldn't find the fault in test tank. So took the boat an a sea trailI lifted the cowl to see if any water was splashing about and got a bolt off one of the ht cables. Fault found number 3 ht cable had a few strands of wire poking out the ht cap faulty from the factory replaced under warranty all was good

Turbodiesel · 22 October 2012, 21:40

Make sure you fit the champion ones they dont like running on anything else.

peterwhite · 22 October 2012, 21:49

Does the engine run normally under load? That would be something to check. Also drain the vapour separator (fuel bowl) and check there's no dirt or water in there.

yam man · 22 October 2012, 22:15

Quote:

Originally Posted by Turbodiesel

Make sure you fit the champion ones they dont like running on anything else.

If I remember turbodiesel u can't fit ngk equivalent as the hex shape (nut) on the plugs are to big the fit in the cylinder head. I may be wrong

Peter_C · 22 October 2012, 23:21

Why where the plugs replaced at 20 hours? Those plugs should be good for over 500+ hours.

The black around the outside edge is not what you look at. Instead it is the white-ish ceramic part that tells the story. With yours they are a light brown. Do you idle a lot? Do you run your boat hard sometimes? If you want to clean everything out open it up! During the break in period a little oil burn will happen causing the outside of the plug to get a black ring quickly.

As asked above how does it run just off idle and at higher engine speeds both under load and by raising the rpm's in neutral?

Downhilldai · 23 October 2012, 00:00

Quote:

Originally Posted by yam man

If I remember turbodiesel u can't fit ngk equivalent as the hex shape (nut) on the plugs are to big the fit in the cylinder head. I may be wrong

Fitted NGKs to mine a couple of months ago and it runs very nicely.

Jason calleja · 23 October 2012, 10:56

I replaced the plugs at the first 20hrs as it is an obligation by the warranty and i run it a lot at high speed and sometimes even at wot
And as i use it in salt water i let it idle in a fresh water tank for a 15min normally and when out of season i start it every 15days in the water tank too. Under load it works perfect.