I have a friend with 2 2003 496 HO engines that he started for the first time the other day. He was only able to get 2500 rpm and thinks it might be fuel pressure. He said he has 45 at key on and then it drops to 30. Anyone know the specs? Any suggestions? I think he needs to get a computer on it, but he can't seem to find access to one. It can't help that the engines have sat not running for 6 years!

45 is about right and the pump relay shuts it off after 3 seconds and the pressure will drop. That's normal. Do a very in depth check on 'em before just firing up after 6 years. Make cerrtain you have fresh fuel all the way through the lines and to the rail (filters & everything).

It could be in guardian mode etc...

Some of the sensors will also limit rpm if faulty, not grounded, on and on.

30psi would be to low, Normaly at key up it will go up to Right around 43 psi and then while at idle it will show around 38 psi untill you unhook the vacuum line going to the fuel regulator then it should go back up to around 43 psi. Do you have a new fuel filter with fresh gas in it at start up?

with the key on engine off pressure will drop below 43-45. running it will/should go back up.

This is the first time these engines have run, so the fuel should be good. He bought the engines years ago with a project boat, and then bought a boat this year to put them in. I haven't worked on the boat. I'm going off of emailed info. Hopefully he'll be able to get it right.

If it is in guardian mode, will it have an audible warning? He's only getting 2500 rpm on both sides with no warning lights or sounds. Like I said, he needs to hook it up to a merc tool.