Sure was running nice as you guys pulled away on the way back

Mine use to do it when I idled a lot . I heard the 500efi are a little rich at idle .Also heard the high octane. I always ran 93 in it and i put A MSD box on it and it helped ..


Ray @ Raylar your saying they changed the mix/blend recently ????


Rob

87 and an msd box cleaned mine up like a champ. if you idle around lots it's gonna happen.

I think he might be refering to the ethanol that is now being blended with most pump fuels.

How much oil does it "burn"? We had a problem with a simple pcv valve on our F2 race boat. Transom was BLACK after a test run right before the race. It didn't do it unless we were running hard.

I would probably say that it's the fuel. California is more stringent on fuel than most states because of the air polution. Maybe the fuel mixtures/ additives have changed somewhat to be causing this?

I saw a report on consumer affairs about 4 yrs ago when they tested different fuels--87,89,91, there was prctically NO difference in the fuels from a few major brands.

There is actually a big difference in fuel quality between different fuels. They all blend their fuels differently with various additives. I only trust and use 76 or Mobil

I have a pair of hp500's and am experiencing the sooting on the transom. I have been told that it is a common issue with these engines. Also been told that the A/F mixture is fattened up at idle to keep from leaning out at high RPMs. I had some relief work done to the heads and the sooting is not as bad as it used to be. Just my .02 worth.....
I run 89 octane most of the time.

ALL 500 leave sooty transoms... they r set rich at the factory... end of story...lean it out w/ a ecm reprogram

I had this "problem" with my 496. Was also told it is normal for this to happen. Someone suggested I add a K&N intake.
I did that. Less black, and not too lean.