4.3 TKS "Run On" fixed but Slight Loss in Performance

[alldodge]

I don't get your meaning here. Not arguing, just not understanding.

He switched to iridium plugs, which would require the .060 gap. I believe.

No I switched from iridium to standard plugs

Not a big fan of iridium just the gap issue

 

[Lou C]

Pulled the Original Factory Installed spark plugs and found AC DELCO p/n 41-101 The plugs look fouled with black carbon from running too hot/lean
These plugs have the following attributes:
Iridium
Heat Range =4
4k-7.5k ohms resistor
Gap 0.060
Socket 5/8 (16mm)
Reach 0.68 in (17.5mm) short reach (measure this with caliper)
Thread 14mm

Fouled with carbon suggests rich fuel mix not lean…
Running hot/lean would show blistered white on the center electrode insulator.

 

[QBhoy]

Fouled with carbon suggests rich fuel mix not lean…
Running hot/lean would show blistered white on the center electrode insulator.

Perhaps thinking that those plugs may have been affected by the tks enrichment mechanism perhaps ?

 

[alldodge]

Might be from run on (dieseling). Its now fixed so run it some more and see if it clears up

 

[Rick Stephens]

Definitely agree with Lou that the plugs look rich, not lean. And not hot, either. Cannot disagree with alldodge that you need to run some more. Personally, I love iridium plugs!

Note that carbon fouling from running rich is enough to cause dieseling. The carbon particles get hot and glow enough to ignite the compressed fuel air mix. Running rich is the most common cause of dieseling and would require either a carb rebuild with particular attention to float height or calibration of the carb.

 

[nola mike]

Definitely agree with Lou that the plugs look rich, not lean. And not hot, either.

Came here to say that. Iridium plugs in these engines would only be for maintenance/longevity. Nothing in my boat lasts long before being changed for one reason or another, or "while I'm in there". So copper is fine for me.