+1 Brian is a great guy!

If all you need is injector cleaning / testing, Kinsler has always done a good job for me:

http://www.kinsler.com/

Phone 248-362-1145
1834 Thunderbird Street
Troy, MI 48084 USA

Agree, the guys are great there...I agree with Boatnt that it seems like a lot of money to keep spending hoping that it gets fixed. The downside is finding someone that is decent to hand over your money to in an attempt to locate the issue.

I was getting a ton of soot, drove me nuts! 2002 496 HO, talked to the previous owner and the ECMs were both reflashed already. I took everyone's advice and switched fuels. Night and day. Still some soot, but I would rather have a little and feel safe than have none and wonder when something bad was going to happen.

I have changed different brands of fuel and different octanes from each brand. While the Sunoco 91 Octane seems to be the best so far (my PCM has the Stage 2 whipple flash and is programed for higher octane fuels), the stumbling and sputtering at mid throttle and the dead spot at about 1/8 throttle has me believeing there is a dripping injector. Also there is raw fuel droplets in the water behind my boat at idle. I would explore other things if it had not been for the oil bath that the intake got when the gaskets were bad.

There is another thread on here, will have to find for you, where the guy was having soot issues...was leaving a film of oil on the back of the boat. His turned out to be a bad intake gasket....something else to consider.

It was him, he already replaced it.

Yup, you beat me to it. Yes, early 496s had thin plastic intake gaskets that would allow oil to be sucked into the intake runners under high vaccum. This cause a very greesy soot that was difficult to clean. That problem has been resolved as what I have now is much finer and much easier to clean. But my issue now is raw fuel exiting the exhaust and a stumble in the mid-range, under heavy load (during planning). Also a dead spot at 1/8th throttle where as you move the throttle forward, there is a point where it actully looses about 200-300 rpm. If you pull the throttle back a tick it will regain the lost RPMS.... The MAP was replaced because it was covered in oil, so it is safe to assume the injectors were splashed with oil as well. At $15-$20 an injector it really isn't that much money if you really think about it... I have seen plenty of 496s in other boats with thru hull exhaust, my soot is not normal. If I run the boat at 3/4 throttle (which would be around 4200 RPM) for 10 minutes the transom will be covered. But I have learned to deal with the soot. It is the raw fuel in the water and the stumbling that is bothering me.

The are a bit pricy at $25 an injector, but they are telling me 1-1/2 to 2 weeks..... I think not!

They were not re-flashed they were completely replaced by Merc with new upgraded models. I believe it was the first year is when the problem was identified and corrected.

low_psi,
Sorry I did not respond sooner I read your PM at 6 AM and forgot about it until reading this......to busy for my own good. My bet is the whipple tune is the problem not the injectors. We had the same problem on Mick's boat with a whipple tune that took 3 times to get it right. First tune turned the sides of the boat black. What is your fuel pressure set at?