My 2006 with less than 50 hours on iit started going into guardian mode every time after about a mile of running early last fall. It will actually completely die but quickly restart if you are heavy on the thottle. Had the 555 read at the dealer and it said the fuel pump relay was the problem. Dealer never had one so I left and picked one up later at another place. Installed the new realay and the problem persisted until I stored it for the winter out of frustration. Right now I am waiting for the newest Diacom software to arrive so I can endeavour to diagnose and solve this myself. Any comments or suggestions would be greatly appreciated.

Are you getting an alarm before it goes into gaurdian ? If so what RPM ?

Yes the alarm sounds, the engine stumbles and you get the beep about every 2 minutes. Typically the RPM is in the mid 2000 range. The Smartcraft screen then shows an engine icon which goes away after shutting down and restarting. Oil pressure, water temp, water pressure, alternator output are all good. The boat will cuise and run for miles in guardian mode.

Guys, there is another issue that can come up for the 6.2's with Cool fuel system, putting the engine in guardian mode. Merc put a redundant filtering system on these for warranty reasons, I guess. There's a tiny s/s filter and "O" ring under the fuel regulator mounted on the cool fuel cylinder.Over time ,impurtiy builds up on this filter and spikes fuel pressure too high levels, dumping too much fuel into the cylinders. Had this problem and noticed fuel dumping out through the exhausts. My Rinda scan tool saved the code for fuel level too high for this. Also, I observed fuel pressure as high as 72lbs at the Schrader valve at idle. The primary fuel pump [ low pressure] has a filter before and the secondary [ high pressure] pump has a dime size s/s filter on the inlet. I removed the small filter that caused the problem with pressure spike [ return line] and it fixed the problem. From the pressure regulator, fuel goes back to the water separator and I think it's suffice to catch debris and easier to clean/replace than slumber down into the bilge ,dealing with the s/s filter.

Yes, check as stated above. Also check your regular fuel filters you should have two. And get a gauge on it for pressure readings. The 2000 RPM alarm is odd I thought the first one was 3500 other than the temp. and low oil.

Thanks for the tip. I change my fuel filters (#21 and #26) every season and never have had a problem you are describing but curious to check it out. Where is the s/s filter located (looking at the drawing) and is it possible to clean and re-install?

Under #10 ,not all of them have it mine is more like a screen. I think thats what is being talked about because I was told to check the as they clog.

The small s/s screen is #14 in the pdf graph http://www.boats.net/parts/search/Me...ler/parts.html

Interestingly, the larger s/s screen isn't shown in the graph for the fuel pump. It's inside the inlet of the pump past #6 fitting and #6 "O" ring. This screen wasn't removable when I had the unit apart so I just blown it clear with compressed air.The little screen is the one with a very fine mesh, hence the greater chance of fouling up.

Mine does not have the cool fuel system that is pictured. I have the original cool fuel return system that goes back thru the separator. There is only one small screen filter at the pressure pump and I believe it is clean because I had the entire system off the engine and appart when the fuel pressure dropped at the schrader valve and the engine died and would not start.

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