How does the fuel tank venting system affect fuel quality and potential fouling?

Sep 22, 2018 ... If all of the spark plugs show heavy dry carbon fouling, the rich fuel mixture may be caused by too much fuel pressure (check for a defective ... Oct 21, 2011 ... I believe if the engine is running too rich at some point it can cause a rich misfire condition in which the HC levels begin to rise along with ... Mar 18, 2020 ... My question is, can this oil consumption cause this bad of spark plugs within about 10K miles or is there other issues that I need to be looking ... Seems to be where it wants to run but plugs still foul (dark black carbon). Jets appear to respond to the lean/rich process and I think they are where they ... Apr 1, 2022 ... Carbon fouling on a spark plug is caused by a problem with the fuel that you use. Often, we describe it as a fuel mixture that's too rich, which ... Sep 9, 2017 ... ... what's causing this for ages and I'm having no luck. I own a 2001 Mx5/Miata and the car is without a doubt running richer than it should (I ... Apr 29, 2012 ... Thanks Jim. I'll check the air control cable. That sounds like a likely cause. There seemed to be good tension at the lever but of course that ... Mar 31, 2010 ... It is possible to foul a spark plug when running it at the proper temp. range, but it isn't very common. One good example would be oil fouling. Please see pic of my carbon-fouled spark plugs just taken out today ... The only two things I know of that will cause fouling like that are overly rich fuel ... Jun 13, 2023 ... I have 1 cylinder in my 1970 440 that carbon fouls, almost positive its a valve issue. All other plugs still look great. (Bosch Platinums).