i have a customer that has 575's with pfm kits (innercoolers and smaller pulleys) on a 40ft v bottem and they keep fouling plugs
i f you put in a new set it's fine for a while take it out run it up to over 5000 rpm bring it back to idle and the plugs are fouled up again.
any ideas?
thanks
Jason

What heat range plugs are you running? They may be too cold.

Also it sounds like you may have carb problems, such as running rich, or a bad powervalve.

575 SCi

If it's a newer 575sci do you have the bigger 6lb pulley vs the 3 lb available? If not PFM has those as well.
There was also a recent recall on the fuel rails check your Merc service bullitens. Did it start when the chillers went on?

I've had to do a new calibration for these, PFM calls for 15lbs. of fuel pressure more and this is far, far too rich. The fuel consumption is unbeliveable, amazing it even runs.

Thanks,
Dustin

I`ve got PFM Superchiller intercoolers on my Top Gun. When I first bought it I was fouling plugs like crazy. I had installed a water pressure valve in the line feeding the intercooler, and with it set correctly, there is no flow through the cooler until 3000-3500 rpm.
With out the valve, the atomized fuel was turning back to a liquid and puddling in the intake manifold at idle. Some cyls. were lean and the back cyls were extermely rich.

Good luck , Kurt.

probally somewhere between timing,octane,and plug heat range,becarefull you dont want to wash out the cylinders or bearings.....you can ruin a good motor in minutes

running one heat range hotter than stock on the spark plugs and not making any difference...... i really haven't got my hands on the boat to check it out .......it's a promo boat and goes to all the poker runs for advertisement for the company so it's always on the go(behind a truck that is)but i feel that it is a atomization problem the plugs are killer black!

Before and after upgrades?Both engines?
Doug