Scanner can read a fuel pressure sensor (IF installed) but your motor doesn't have one that I've found

There is a screen filter below the filter, but that is normally replaced when doing a filter change

Fuel pressure should be 39 PSI at idle and 43 PSI at WOT. Can check for high pressure output by removing the vacuum line from the Reg at idle

My guess (only a guess) is if pressure is within spec, then I would think of the MAP sensor. If they go out of spec, they can make the fuel mix go rich or lean. The scanner will tell if its out of spec

It might have damaged the ecu with an arcing wire.

ok thanks! You've been really helpful. I know where to start at least. Have a good memorial weekend.

IF you end up going to buy wires, you’ll see merc sets are like $600 snd once your heart attack is over, look here. We’ve given part #’s that are less than $100. Some OEM and some good aftermarket like Moroso.

There is a recent thread too.

How did you determine the extra 15% fuel burn, Smartcraft? Or was is based on actual gallons used from fill up to fill up? If you are missing 15% of your fuel from that motor then it's going somewhere either a fuel leak or that motor is dumping fuel in at a rapid rate. Do you have excessive exhaust odor when running?

You need to get a pressure gauge on the fuel rail at the schraeder valve. I bet its reading way high.

Each time I fill the tanks I always need to put in more in the port side just to get the guages even. Then I can run the boat for a weekend and the gauge is showing a lot less fuel on the port side. Also, I have some other clues. The part plugs were black. I see a film in the water when the engine is running. But most of all, that engine has a bad exhaust smell. I thought it was just the way the boat is until one day I decided to run just the starboard motor and we had NO exhaust smell the whole time crusing around.

I just bought a new fuel regulator hoping that's it. I will also get a fuel pressure gauge.
If its not the regulator what else could it be?

Note, the boat has done this since I bought it 9 months ago. But I had all fuel lines and filters replaced 3 months ago. I keep hearing about some sort of screen that gets clogged but Idon't know where this is at. I have a gen 3 fuel cooler so its not there.

The symptoms you describe are all indicative of the cool fuel paint problem. Check the fuel pressure with a mechanical gauge and check the regulator/damper for clogging with paint. Have you pulled the cool fuel filter assembly on the problem motor? You can see telltale signs in there as well.

But I would bet you have the paint in your fuel system and its made its mess. If so, you need new cool fuel$ unit, thorough cleaning of the rail, new regulator damper, and send out all 8 injectors for service. If one motor has it, the other is close behind.

Sorry.....

Man, that would be a bummer.
My engines are remanufactured 2014s. So do think the paint issue even existed from that time? I thought it was earlier.
I did do the other engine cool fuel filters and they actually looked pretty clean. But I didn't look to see if it was painted inside.

Does that regulator just pull right out? its on top of the unit with a vacuum line right? I didn't see how it would come out when I glanced at it and the diagram doesn't show.

According to Merc this affects all sterndrive 496 models equipped with Gen III cool fuel 1A349420 and below

The regulator/dampener thingy is on the fuel rail and you have to pull some parts off to get at it. If you pull it you have to install a new o-ring to reinstall.

I would get the mechanical reading before you start digging.

Search the web and OSO...this issue has been covered to death.

ok thanks. I have a Rinda scanner on order. Also a fuel pressure gauge and a few of those dampener orings.
maybe I'll get lucky and it won't be a paint issue. Funny thing is, the engine runs strong. Full RPMs and never a problem. It just uses more fuel and smells. I would think if its the paint problem I've been reading about, I would get misfires, restricted fuel, or something of that nature.

So if the fuel reading is fine and the dampener looks clean (and cool fuel housing isn't flaking) then I assume I'm safe for now and it's some other problem right?