2001 - 300X on 21' Liberator, laying down after 4000 rpm

[bocephus]

Just bought a 21' Liberator w/ 2001 300X. Very rough water when 1st testing. Smooth today but, it lays down at 4000 rpm will come up a little more but starts hesitating and shaking, almost like its skipping. Maybe starving. Tank was empty when i got it. I did change the fuel filter on the side of the engine. Nasty fuel was in it. Spark plugs are all dark brown. Idles good. Runs good up to 4k. Anybody have any tips?

[Merc 2.5]

Does it act like runnin outta gas ? Low pressure/ diaphragm pump? Injectors? Have u looked at plugs? I'm no 3.0 guy

[Euroski]

I would start with cleaning injectors.

This company may be close. He's very good
https://www.boatunlimited.com

[kellytheaker]

I' not the knowledge base your needing but first thought is your going to be directed to start at basics as 2 members have stated fuel . I believe they will also mention compression soon or a DDT scan . But is it in limp mode ? I' not aware of what rpm that it would go to but sounds possible . Basics - compression - rule stuff out and don' skip forward a step or you may get caught and miss it . A simple scan for a few bucks may be beneficial and pinpoint immediately . Hope this helps

[Chaz]

If it has been apart recently, the easy way to fill the external oil lines and to give it a good start on a new life is to put in into break-in mode.
Which feeds it double oil and limits RPM to 4000-4500 for an hour of loaded, above an idle running.
Not sayiing that's it, without looking at it. But that's what it sounds like from what you described.

[bocephus]

Thanks guys but, it, has not been apart & i already mentioned i checked the plugs. Everybody know they can go to the Dealership.

Thanks for the website Euroski. It dose kinda feel like its running out of something. The shaking and skipping part makes me think fire but, it could be gas. This is my 1st dealings with a 3 liter. Dang sure not as simple as a Drag motor....lol

[Beak Boater]

Since injectors have already been mentioned, does it have a fuel water separator filter mounted some where on the transom. Not sure if Liberator uses a tank with a check valve in the elbow coming out of the top of the tank. They can cause problems especially if the boat has been sitting as well as the fuel line if it has a squeeze ball it has a check valve in it as well that can cause a decrease in fuel flow if its bad.

[Euroski]

When I had a 2007 300XS which had mercury spin on fuel filter setup before the engine, and I had to have injectors cleaned at 150hrs

[vnemous]

Coil driver runs two cylinders, sometimes they come unglued and fail. I would check to make sure the three of them are good. JMO

[InjectorService]

I'd try running with a fuel pressure gauge attached and monitor your fuel pressure before and after 4000RPM. If it drops, you know you have a fuel supply issue. If not, could be injectors or spark related.

[Chaz]

Thanks guys but, it, has not been apart & i already mentioned i checked the plugs. Everybody know they can go to the Dealership.

It dose kinda feel like its running out of something. The shaking and skipping part makes me think fire but, it could be gas.

I know it's frustrating, but keep in mind ... people are trying to help YOU with YOUR problem.

All suggestions that were given ... are valid.

Stating that you just got the boat, been in it only twice and the first time waqs too rough to go fast ... and that you checked the plugs ... is not a lot to go on.

There are a handful of test's to be done with an ohmmeter.

Tire pressure gauge .. yes look, there's a Shrader valve on the VST tank.

Of course the quick and easy way ... would be to hook it to a good diagnostic tool where you can look at 4000 rpm. Freezeframe and see if there are any injector misfires, or a breakdown in the ignition system. Naturally, it will tell you which cylinder, how many times it occurred. The codes printed will point you to the problem.
It will even tell you if someone turned to the key to "run" .. put it "in gear" and "pumped the throttle three to five time" ... which put it back in break-in mode. At that point, it's even smart enough to tell you how much longer it will linger in that mode.

[Chaz]

Coil driver runs two cylinders, sometimes they come unglued and fail. I would check to make sure the three of them are good. JMO

2001 - 300X

Hummmm ...

Chaz = wunderin, does it have twin Pancakes on the back .. ?

Or a single Motorola on the starboard side ... ?

[vnemous]

2001 - 300X

Hummmm ...

Chaz = wunderin, does it have twin Pancakes on the back .. ?



Or a single Motorola on the starboard side ... ?

Am I in a state of confusion with by 250EFI???? I defer

[vnemous]

You made me go to the parts catalog buddy 2001 300x Motorola single computer I'll get over sometime next week for lunch, had some projects going on.

[Chaz]

Am I in a state of confusion with by 250EFI???? I defer

Me too ... I hate the "early / late models" with their some of this and some of that parts list. (It's like my spaghetti sauce)
Seem's like they didn't run out of parts and had to commit to being a true late-model till around 2002 1/2 ( 225-250-300) models ..
Curiosity got the better of me when I saw the X in your sig, is a 01 . Then it dawned on me I have a 01 harness with a burned wire in the cannon plug. The coil plate that came with that harness are married together. Until I fix that wire, both are useless ... 4 vs 5 wire.

Chaz = also rememberin, You and John fixed that 250 EFI ... in ten minutes