dana marine products

Most likely if you richen it up you'll lose more power. On the dyno, we played with a Raylar 525 kit, and started the fuel pressure at 52 lbs and worked it down to 47-48 (idle pressures) where it made the most power, and it was perfectly safe. (Raylar was there assisting in the project).

We had one boat that did not sound an audible alarm, but was shutting down on power because of excessive water pressure in the system. Once we free'd it up, off she went. It never sounded an alarm, or showed on a scan tool after the boat was on the trailer.

Rage

One tid bit per Mercury Marine c/o Dustin Whipple, the PCM555 ECU does not record knock events nor does it go into Guardian mode as a result. The PCM555 will only retard the spark if it senses a knock event. So a knock event will not show up in the PCM555 fault history. I did not ask if the PCM555 will record a reduction in power as a result of a knock event or sound an alarm but I would suspect not.

speedygonzalez

You touched on something that I'm curios about, my water preasure reads 2.5 lbs on diacom, but it's not overheating right exhaust is at 110 left 120 , engine temp is @ 175 which is normal. Now ,that could mean I have good volume and it's what maybe keeping it cool.

Rage

I sure would not reduce fuel pressure from the 50 psi that the kit is set up for unless you're capable of measuring the A/F on both banks. 12.5 A/F is generally reported as the prefered target for safe and optimum marine power with 13.0 the absolute maximum. Based on some lean A/F dyno numbers a 496 Raylar engine was leaned out in search of the max (dyno) HP by reducing fuel pressure which in the end resulted in a melted a piston. An engine can tolerate a lean A/F for a short burst dyno run that would kill it if used in the boat. Proceed with caution. Just my $0.02.

dana marine products

Your water temps are fine, the 2.5 lbs of pressure seems really low. Is that at idle? Any excessive pressure issue would have to be measured once the engine is up and running hard. At the 4300 rpm range where your motor shuts down, what is the water pressure?

bobl

If you hit record on the Diacom it will record all the parameters, including knock retard and water pressure. If your water pressure is that low (or has a false low reading) it will go into guardian.

speedygonzalez

The preasure was at idle with the hose on it, I can't recall if there was much change on the water. I will check it on Tuesday on the water.
I know that if I richen it the possibility exists that I may possibly loose power,but if infact it is running too lean I risck more than just power.
Now the motor does not shut down nor go into safe mode, it just won't go over 4300 RPM after fully trimed out.
That will be the next thing I have to deal with I suspect my X dimension is also off, but will be anothr thread for latter.
Not to confuse things,the motor did do 4900 RPM before the headers.

muffman

I have Lightnings and have no problems.

Nordicflame

iTrader: (4)

The problem is not the headers or fuel pressure.
Find your Gremlin. 4300 is the guardian mode.

speedygonzalez

I will retest and record and find that grimlin