2003 6.2 Bravo going into guardian mode with no alarms

MasterFab said:
The previous posts concerning the cap/rotor are correct, and this is an easy fix if it solves the problem. If not, I would go right for the fuel filter. You did indicate the problem manifested after slogging through some pretty rough conditions, and this is exactly when any loose crap in your tanks would wind up in the filter, clogging it to the point that full power is not available, but reduced power is. Change the fuel filter(s), see what happens, and let us know!

Good luck with it.

Dale
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When you speak of the fuel filter are you talking about the water seperator?
 
Great lakes pirate said:
When you speak of the fuel filter are you talking about the water seperator?
Click to expand...

Your boat has water separating fuel filter and a traditional fuel filter.
If debris in the filter are reducing fuel flow then it’s the traditional fuel filter.




------------Fuel filter ----------------
(2) Fuel filter = 864572 JMS online @ $35/each
Permatex PX# 56521 at Napa for about $15 for one little tube.


Turn your fuel shut-off dial. This is a small dial. Follow the fuel line from your fuel filter back to the fuel tank and you will find the fuel shut-off dial. Just turn the dial.

Do not put a wrench on the aluminum fuel filter itself. Put one ¾” wrench on the first brass fitting and a second wrench on the second brass fitting.

Hold the first wrench still and unscrew with the second fitting. Once the filter is out then remove the brass fitting from the filter.

Put thread lock on the male thread that goes into the aluminum filter when reinstalling. Loosen the compression fittings one flat and then you can take them off by hand, and then the entire filter, with its double male nipples can be removed.

Unscrew the double male fittings, use Permatex PX# 56521 on threads, install the double male nipples in the new filter, reverse the above process and you are done.

A small amount of fuel will come out when you crack the compression fittings one flat. When you remove the filter, hold it horizontal, then dump it from the “inflow” end into a clear jar for fuel examination.
 
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Well we brought the boat back home tonight and she ran OK.... Nothing was wrapped up in the props nor was there anything blocking the water pick-up. I had to push the starboard throttle further than the port 20-30% to sync the engines. So, I plan to swap out the rotors and fuel filters on friday and then plug the rinda code reader in and see if there are any faults stored in the freeze frame.
 
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I replaced the rotors and in-line fuel filters this weekend. Starboard engine is still not running right. It seems very suggish compared to the port. It is also burning more fuel. Due to a busy weekend I ran out of time and didn't get to play with the code reader. Replaced - plugs, wires, rotors, distributors, fuel filters so far. What is the best way to check fuel line pressure? Can anyone suggest a decent pressure gauge?
 
My mechanic came down to the boat today and checked fuel pressure. When I fired up the engine it showed good pressure. When I accelerated the pressure dropped off 8 PSI. He says I need a fuel pump. I looked on-line and it shows 2 pumps for my boat. How do I know which one to replace?
 
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After doing some research last night I found out that there was a service bulletin for my cool Fuel 2 system. Apperently I can't just purchase a fuel pump. I need to buy a kit that includes a pump and a new fuel cooler. $600 vs. $250 for just the pump.

http://www.mercruiserparts.com/bulletins/001/04//2004/EN_05.PDF

The original pump merc. part # was 807949A 1. This would allow me to change the pump with out buying the whole kit and is under $200. I called merc and explained my situation. I asked if they could tell me why they changed the cooling tube. They could not explain why the SB was issued.
 
I am not sure if I am going to buy the kit (cooler/pump) or just the original pump. Looking for some advice from the group. Has anyone followed the service bulletin and swapped out the whole shebang?
 
I removed the pump last night and it appears that the PO followed the service bulletin and replaced the pump and cooler. Now I am in search of the pump part#861156-1. I can find it on eBay but none of the local dealers have the pump. I was planning on heading out of town today but unless I find a comparable pump I will be out of luck. Bummer!
 
I replaced the high pressure fuel pump over the weekend. Took her out for a spin and same symptoms. I hooked up a fuel pressure gauge and took it back out. It read 45 psi at all RPM's. So, now I know that fuel pressure is good and I think it can be ruled out.

IAC problems... The engine sounds like it is sucking a ton of air. Way more that the port. We hooked up the scan tool and tried to manually shift the IAC valve and it would not respond.

We think the valve is stuck open and causing the sucking noise. I had a new IAC on board so we swapped it out. We took the flame arrestor off and the damn muffler was MIA. It was replaced in the spring. Can a missing muffler cause this sound? Where did it go. If it did end up getting sucked in would the temps. in the combustion chamber disintegrate the muffler? I checked all of the hoses connected to the valve and could not find it.

After all of the new parts my mechanic now thinks the problem is timing. During the test run when the scanner was hooked up it read 24 degrees advanced at WOT. Does this sound right? He says it should advance more. How do I properly check the timing?

Today the port engine ran at 4800 RPM's, Starboard 4200RPM's at WOT.
 
Great lakes pirate said:
......Can a missing muffler cause this sound? Where did it go. If it did end up getting sucked in would the temps. in the combustion chamber disintegrate the muffler?
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#1) Yes. I personally feel the sound is almost a whistle.
#2) Most likely the muffler filter went into the throttle body assembly and down into the intake manifold.
#3) Its depends. The Merc 6.2L V8 begins life as a GM 5.7L V8. Mercury strokes (lengthens the piston travel distance) to get additional displacement.

In addition to this stroking they created a ‘tuned-port’ inside the intake manifold. This is one of the reasons why you should never pour fogging solution into the intake of a Merc 6.2.

To answer your question, is the muffler filter still in there, the answer is it depends which port it fell into.

I do not have enough experience with a 6.2 so I cannot say if a IAC muffler filter lodged in a tuned port of a intake manifold could cause enough restricted airflow to be the root cause of your performance issue.
 
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More fun! Changed the plugs again. #3 and #7 were wet with gas. Took her back out for a rip and had the rinda plugged in while under way. The scanner had "guardian mode - unspecified fault" on the display. Turned around and parked her. Has anyone ever seen this problem before?
 
UPDATE.....2003 6.2 Bravo going into guardian mode with no alarms

Presentation said:
I am going to suggest that your engine is not in guardian mode and a code reader would show nothing.

Did you install a sierra rotor and cap or merc? Sierra is having some known issues.

My suggestion is to put your old Merc distributor cap and rotor back on the issue engine then see if this resolves the issue.
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Well we finally brought our engine back to life and PRES....... you hit it on the head. I had one of those bad distributer caps. I finally swaped it out with a new merc and now we have full power again.
 
Re: UPDATE.....2003 6.2 Bravo going into guardian mode with no alarms

Great lakes pirate said:
Well we finally brought our engine back to life and PRES....... you hit it on the head. I had one of those bad distributer caps. I finally swaped it out with a new merc and now we have full power again.
Click to expand...

I'm very glad you got it fixed! Now go enjoy some boating.
 
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