2006 Malibu 23LSV 8.1 help- loss of power and rough idle

[Tsumi]

We just got a new to us 2006 Wakesetter 23LSV with the 8.1 that's been giving us issues. It originally started with the occasional loss of power while at around 2800 RPM; there was a change in the engine tone and a slight lowering of speed. There was also the smell of fuel in the exhaust. At idle it felt rough, and it has since transitioned from occasional to permanent. Under heavy ballast (MLS full, wakemaker's piggyback in the rear with ~500 lbs in each) with a 14.75x15.25 OJ prop it cannot go faster than 12 mph (wakemaker's piggyback was added after we started having issues so not sure how performance was before). We've replaced spark plugs, wires, and coils. The last time out we started getting a check engine warning at idle and could not throttle up at all.

Planning on trying to pull the codes the next time we can get to the boat, but any ideas on where to look next? I'm thinking crank position sensor at this point. We're also planning on checking fuel pressure.

[justgary]

Fuel pressure seems like a great place to start looking.

[PNWoke]

@Tsumi  I’d replace the fuel filter.  I usually find that a common google search of “themalibucrew xxx problems” works better than the search function on the website here.  Decent thread here: 

Another decent thread:

Also maybe give indmar a call and tell them about the issues.  There were some threads that mentioned reflashing the ecu’s, and some other good info that they shared.

Edited June 8, 2022 by PNWoke

[Tsumi]

Thanks for the replies.

I've seen the ECM threads and I don't think they apply in our scenario. It seems primarily 07 and newer boats. Also, we're operating at 500 feet.

I'll check fuel pressure and pull the codes.

[justgary]

32 minutes ago, Tsumi said:

pull the codes.

Heck, build a data cable and read all of the parameters.  I'm pretty sure you have a MEFI4 ECM, but I'm always wrong about that sort of stuff....

 

[Tsumi]

Got a fuel pressure meter on it, 90 psi at idle. Will definitely be replacing the fuel regulator.