Guys,

Just joined since this looked like a place that could offer some help. I'm helping a friend troubleshoot a problem his boat is having. It's a 2004 Sea Ray 240 Sundancer with a 5.0 MPI/Bravo, right around 500 hours.. The boat will not go over 3,000 RPMs. This started fairly recently and we can't figure it out. It has fresh fuel, new fuel/water separator, new spark plugs, plug wires look OK, haven't looked a the cap/rotor yet, fluid levels are all OK and topped off. The throttle body opens all the way and the spark arrestor is not plugged.

The boat simply will not go past 3,000 RPMs. This problems started a bit ago and he's been waiting on the mechanic to look at it but the guy is busy so I decided to offer some help. There's no alarms present on the SmartCraft gauge. All pressures and temps look OK on the gauge. I'm an outboard guy, but have fooled with race cars for some time so the whole outdrive/gimbal assembly thing is new to me but the engine is not.

Even though the SmartCraft gauge shows good pressures and temps how can we check the things like TPS, coolant temp, oil pressure, knock sensor, etc. that the ECM is seeing? Can only a Mercruiser mechanic scan it? Or is there a way we can plug in an OBD reader to scan for codes? I looked for a bit on the harness and didn't see an OBD port.

Thanks in advance.

John

You need a Rinda Techmate Scan tool to scan it.
Does it basically cut out at 3000rpms?? Pull back throttle a little and its fine?? If so, My bet is on cap/rotor

Definitely get it scanned before putting in to much effort. There is not an OBD 2 port and it requires a special computer.

Fuel pressure should be pretty easy for you to check on your own

It doesn't cut out at 3K, just stops climbing in RPM and sits there running as smooth as can be...

Pulling back on the throttle does nothing except decrease RPM. We have a cap and rotor coming. We're limited in what parts we can easily get in this small town in Colorado. Thanks for the tip on the scan tool. That's what a bunch of others are recommending.

I plan on checking rail pressure and seeing if Sea Ray has another filter installed somewhere before the small lift pump. As for scanning it's been hard to find a local mechanic with the scan tool available to do so.

I think you can buy the scan tool for about $600 and there are probably a few used ones that can be had for considerably less. I wouldn't own a EFI engine that I didn't have a scanner for. Who wants to wait 6 weeks for some dealer to get you in.
Start with the basics and you will find the problem 90% of the time.
Scan it
fuel pressure
ignition (plugs, wires, cap and rotor)
compression test
check condition of the prop and the hull bottom.

Props just replaced ?

First time in high altitude ?

Trailer still attached ? :wink

Never assume anything

Looking into scanners now. The local mechanic doesn't have the latest Merc stuff and doesn't seem interested in trying to get it scanned. We'll be checking fuel pressure when we go back along with compression. Already did the water separator and plugs since those were easy to get from the local parts store. Cap/rotor on order. Hull and outdrive is clean, that's the first thing I checked.

Same props and it's been at 6,000' of elevation for awhile

Winterized properly? Definitely do a compression check and better yet a leakdown test