06laser

hey everyone new to the forum here. i have a 2006 496 mag and last season i starting having a problem with it. before the season started i did a gimbal bearing seals ect in the drive, oil change, the two fuel filters in the cool fuel gen module and checked everything else. the boat ran fine for the first 5-6 trips after that my alarm was going off if the boat would go over 3000 rpm. i would have to power all the way down to idle then i would be able to take off again. it runs fine under 3000 rmp. it feels like i loose fuel pressure and it just shuts down. i just got the boat back home and checked the fuel pressure. cycled the key 3 times to get maximum pressure and the gauge reads 45psi, at idle its at 37psi. could my problem be the high pressure fuel pump in the fuel pump? any help would be appreciated thanks. bryan

thirdchildhood

iTrader: (6)

Maybe overheating alarm? Did you suck up some crap and clog the heat exchanger?

06laser

i havent checked that yet i just got it home and the first thing i checked was the fuel pressure. ill take a look at that and make sure its not clogged.

downtime270

When the alarm goes off what type of beep is it? Do you notice the engine breaking up or the tach fluttering? Have you plugged into the ECM to read the codes? I have a few thoughts but need some more info. I have ALOT of experience with this motor, and tracking down a gremlin...Let me know.

06laser

its a solid alram (constant), it feels like it goes into a limp mode like sputters until i bring it down to idle. once i bring it down to idle the alarm will go off and i can take back off as long as a dont go over that certain rmp. i havent scanned it yet. i personally dont have a scanner i would just hate to take it to someone pay them and nothing show up.

Dave M

If you have an alarm, a scan should reveal the problem. Don't waste time guessing.

These are the conditions that produce a constant alarm
Coolant overheat
low oil pressure
overspeed
sea pump psi low
port and stbd exhaust overheat

When is the last time you replaced the sea pump impellor?

downtime270

So - I spent roughly 2 summers, and thousands of dollars searching for a very similar issue. I did use a scan tool, and I replaced a number of parts based on the ECM data. However none of it resolved the issue. It ended up being the routing of the knock sensor wire in too close proximity to the spark plug wires. I would run the boat and it would alarm anywhere from 2800 - 3200 which was the cruise range for my boat, but the alarm would stop if I reved past the RPM range, or dropped back to idle. Since you were in the area of the fuel system cooling maybe you moved the spark plug wire or the knock sensor wires. I would suggest you take a very close look at this before you lay out any cash. While the ECM will give you good info - if it isn't sticking a hard code - it won't help. If you do get a scan, I can tell you this issue caused both cam/crank sensor codes as the ECM was having issues determining if the faulty signal from the knock sensor... I just love electronics! Oh btw I did go through coil packs, fuel filters, fuel rail insp. and cleaning, fuel pressure checks, plug wires, plugs, etc...etc...

06laser

my impellor was replaced when i did my gimbal bearing, fuel filters ect... that was all done less than a year ago.

Raylar

The alarm went off so you have fault codes stored in the ECM that may direct you to a simple fix. Scan it first and then start doing other things. It could be difficult to start just replacing things without the fault codes. Check EM!

Best Regards,
Ray @ Raylar

06laser

i read on the mercury service bulletin that if the fuel pressure is more than 44psi when cycling the key to replace the cool fuel module and in the water test is says if its lower than 40psi to replace the module. could 1psi cause a problem? i didnt really run a in water test i just started with the muffs on the drive and it was at 37psi at idle. if it was a wire or something i dont see why it would have ran fine for my first 5-6 trips roughly 6-8hrs of operating time then start acting up but i dunno.