Spark Plug Color after use question...
 

I just pulled out the AC Delco Rapid Fire #1s that I put in; in March. They have about 25-30 hours on them. Only two of them showed any sign of turning brownish/tan. This is a 1999 HP500EFI with stock everything and stock ECU. This config is notorious for running rich; so that does not make sense to me. Any ideas why my plugs are still white? I just put in the updated recommendation for NGK BR6FS today, so I will look at them in a few weeks. THANKS!

As you said, those plugs should be dark with fuel. Have you checked the e.c.u. for any stored codes? What is the fuel pressure?

I pulled a Rapid Fire #1 the afternoon as well. It had no color with quite a few hours on it. Im carbed so I went up a couple sizes and tried again. Boat slightly sluggish...still no color. I think they used non stick teflon instead of porcelain!

I will check those out C454M, thanks!

I'm having the same issue...
 

pulled my plugs the other day, while changing the cap and rotor. They were white, hardly any color if at all. checked the accelerator pump and see its in its richest position, was going to pull the carb apart and check the primary jet. Motor is a 96 carbed 300hp 454. Runs strong, but this plug issue has me a bit concerned..

Todays gas really runs too clean to mark the plugs very much unless you are running incredibly rich or lean enough to melt them. This is especially true of EFI applications. If you want to read the plugs, try running race gas, leaded of possible, it will give more visible marking. Checking exhaust temp( upstream of the water) is more accurate today.

good advice GO4BROKE!

then is that set up good enough when
 

you go back to unleaded gas?

TTT, thanks everyone!