350 mag mpi 2011, low fuel pressure

[Mickeypowa]

Hello!
I have a problem with my 2001 malibu response equipped with a 2011 mercruiser 350 mag mpi.
When I try to go to the max rpm : I can only go to 3500 rpm whereas before I was able to go over 4200!
When the engine is hot, there is a bit of smoke with an gas smell.
I already changed spark plugs, rotor cap, water separator filter, inline fuel filter.
I made an ecm scan and I have no error code!
I tested my fuel pressure : I have only 25psi priming the pump, 30 psi when running at idle, and 28-30 psi when I rev.
I have the cooler pump system and boost pump, so I should have 43 PSI!
If I prime the pump, then the pressure decrease quite quickly.
If I disconnect the vacuum hose from the fuel pressure regulator it doesn't change anything!
Here is a video of the pressure gauge :

So do you think I should change the fuel pressure regulator? Or the high pressure fuel pump? Or both?
What can I test, to know if its one or the other ?

Thanks a lot

Mickeypowa

 

[alldodge]

A 01 boat with a 2011 motor. Was the new motor the same configuration as the 01, or is it a motor with catalytic exhaust?

 

[Mickeypowa]

When I bought the boat there was already this 350 mag mpi inside. It a pcm555 without catalytic exhaust.

 

[alldodge]

Would be good to have the serial number but being a 555 ECM it should be 43 psi.

Does the motor have the Gen 2 (single pump port side) or Gen 3 cool fuel (pump box starboard side)?

If Gen 2, remove the regulator and need a air compressor with adjustable air regulator, gauge and rubber tip connection. Connect air to inlet port and slowly adjust air pressure to see when reg opens.

Do similar test with reg if Gen 3

 

[Mickeypowa]

It is the gen 3 I think, with cool fuel starboard, and boost pump port side.

Is it possible that the problem come from the regulator that stays always open ? always lowering the pressure

 

[alldodge]

With a boost pump on starboard side then you have a Gen 2 with a boost pump. Your reg is on the port side.

The Gen 3 looks like this and there is 2 pumps inside the unit

My guess is its the Reg but testing will verify.
This is your motor, (without SN not real sure)
https://www.mercruiserparts.com/350-mag-mpi-ski-0w690000-thru-1a089999

This is the cool fuel and item 13 is 861126A1 at 43 psi
https://www.mercruiserparts.com/bam/subassembly/31404/12844/50

 

[Mickeypowa]

No sorry I made a mistake : I have the cool fuel system on port side, and a boost pump (low pressure) on starboard side ! So yes I have a gen 2 with an additional boost pump!

Yes you are right, I have the same system with 86112a1 but actually my engine is that one :

MerCruiser 350 Mag MPI Alpha / Bravo Fuel Pump & Fuel Cooler Parts

MerCruiser 350 mag mpi alpha/bravo fuel pump and fuel cooler parts. Buy a genuine Mercury Quicksilver or aftermarket part.

www.marineengine.com

Ok I will try to change the regulator first as I don't have an air compressor to test!! Thanks

 

[QBhoy]

I’d check that fuel pump system and regulator.
but only thing confusing me is if it has a smell of fuel and running rich like you say...that’s the opposite of a sign of not enough fuel or a restriction. Perhaps I’m now thinking along the lines of an injector staying open when it should be ? Might be agreeing with the reason AD had asked about the ECU set up etc.

 

[metsfan3197843]

Pull the vacuum line off the dampening (also called dummy) regulator and see if there is fuel in the vacuum system. Had a friend with the same symptoms as yours and the upper regulator diaphragm was bad causing fuel pressure issues and smelling fuel due to it being sucked into the intake in the vacuum line. Best of luck