Logo
FULL SITE MENU

09' 496 HO fuel issue

B

Bhall1116

New member
last leg with this issue. I recently purchase an albemarle 265 express with a 496 mercruiserHO with Bravo III.

My first run with it about 10 minutes into 4200rpm the engine alarm sounded and merc went into guardian mode. Did this a few times. It has 2 gas tanks. Runs off one water separator.

Finally isolated the tanks. Runs perfect on the starboard tank no alarms or any power issues. When I turn the starboard tank off and switch to the port the engine goes into gaurdian mode. (Brings engine Down to a "limp mode"). I can turn the boat off and take off again but eventually alarm sounds.

Currently I have :
Changed anti siphon
Changed fuel line
Pulled and inspected pick up tube (no issues)
Checked vent by blowing into from transom. (No blocking)
Cleaned most fittings.

I'm at a loss of things to check that would cause this issue.

Any ideas would be greatly appreciated
 
Last edited:
Does your boat use the smart craft feature? And if so, do you know if the fuel tank level sending units are connected to the engines smart craft system to where you read fuel level via a digital type display through the smart craft system/gauges?

How do you switch from one tank to the other? Is it somehow electrically connected to and read through the smart craft features?

If so than that may just be your interlaying problems as this engine shouldn't have a fuel pressure sensor that would put the engine into "guardian mode" sounding a warning horn should you actually have low fuel pressure between the fuel tank to the engine injectors. You'll still want to check the fuel pressure anyways just to be 100% sure what the pressure really is between both tanks.

What is your engine serial number?
 
Thanks for your help!

it is running all analog gauges there is no smart craft gauges hooked up. The boat is an albemarle 265 express 2002. Repowerd in 2009.

There are manual shutoffs for each tank in the engine compartment. Today I replaced that whole assembly.
Same it is still happening.

i took it out today and even on the starboard tank it I can't go over 4200 rpms. seems like it may be stuck in gaurdian mode?

i haven't put a pressure gauge on the lines yet. I'm thinking that is the next step.
 
Yes now that you know the engine will only run up to about 4200 on both tanks helps tell you that you have an engine issue and not a boat side issue and if the warning horn is sounding then that is also on the engine side and it usually is not fuel related as again there is no "fuel" pressure related sensors to sound the alarm on the 496's.

What was in the boat prior to the new 496 including the what drive and transom assembly did the boat original come with? Are the drive and or Transom assembly new with the engine too?

Besides the alarm and not going over 4200, Does the engine seem to run fine otherwise such as idle speed is good/normal, acceleration goes up almost normal without hesitation, backfire type sounds, etc.?

If the engine seems to run "okay" then there should be more of an issue with one of the engine's MPI sensors being out of range such as the water pump pressure is a common issue that is hard to pick up as far as putting out a fault code. To find a water PSI issue, a marine scan tool helps a lot and a mechanical water pressure gauge helps with confirming the actual water pressure wen you install it in place of the water pressure sensor as a test.
 
the out drive is a bravo 3 also new in 2009.

Yes everything seems to run great and sound great.
Its weird because once I switch to the port tank I get all the alarms. Once I hit 1000rpm. But if I switch back to starboard (after about 10 min of idle speed) I get no alarms at all. I'm confused. Not sure where to start next.

i have been trying to get a merc mechanic down to scan it but everyone is "too busy" are the scan tools I can buy worth it? I know the computer software is proprietary.
 
Back
Top