[ReelMagic]

I own a 2003 38 Open w/twin Cummins 450 CTA Diamond diesels and am experiencing an issue with the starboard engine spooling up slowly during acceleration.. When accelerating from idle to cruise RPM the starboard engine is slow in spooling up. Thought it may be the primary fuel filter (RACOR) so I changed it.... Vacuum gauge on RACOR reads 2 hg following filter change and after several accelerations from idle to cruise although engine still slow to spool up.. Port engine is fine and spools up quickly. Has anyone experienced a simllar issue and if so what was it???

[trit21]

There are several things it could be. Have you changed the secondary on engine fuel filter? Does it produce black smoke while trying to spool up? Do you have boost gauges to determine intake air pressure? when was the last time the after coolers were cleaned? Check the ensure the fuel solenoid is fully engaging. Probably not the problem but good to check. Maybe the fuel linkage has slipped and is not allowing fuel throttle advance? Check the basics first and then dig deeper. Bottom clean? Something wrapped on the star prop?

[ReelMagic]

Thanks for the reply and suggestions... Changed both the Racors and the on Engine secondary filters... Racor vacuum gauge reads 1.5 hg so the Racors are OK.... Aftercoolers cleaned less that 150 hrs back. No black smoke on acceleration..Don't have boost gauges so I'm at a disadvantage there... Believe throttle didn't slip as I still I full throttle, 2600 RPM.... I starting to think it's the lift pump but can't prove. any suggestions is greatly appreciated.

[trit21]

Air cleaner clean? Is the bottom fouled at all? Why are you thinking it is the lift pump? I am not super familiar with the CTA's as i have BTA's but I like to totally eliminate easy issue before taking engine parts off, cheaper you know. Not saying it is not the lift pump. Did just all of a sudden become an issue or has it been getting worse over time?

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Have you checked your no load WOT?

[jclark003]

You may also want to pull the air cleaner and try to spin the compressor wheel by hand. It should spin freely. Otherwise I think the c series has a mechanical solinoid (have heard it called an "aneroid" valve). It increases fuel ratio ahead of boost to increase acceleration. If it fails or gets out of spec it can result in very poor acceleration. I would suggest you go onto boatdiesel.com, pay the $25 to become a member and do a search for "aneroid". There are several posts that describe a relatively simple test. You also may get other ideas of things to look for but I think trit21 has covered the things to check first.

[ReelMagic]

That's to all for the responses.. Airseps clean as well as the bottom.... I'm not looking for a complicated or expensive solution. Prefer a simple and cheap one if that solves the problem... Problem is recent and somewhat intermittent.. Appears to happen after running for a while and then stopping to drift fish for an hour or so.... Will look into the mechanical solenoid (called an "aneroid" valve) by jclark003....  That fits an intermittent problem... Will keep all informed as to what I find out..... Will join BOATDIESEL.com as well..

[trit21]

I would also go to SBMAR.com, no cost to join and that is Tony Athen's website. Wealth of information there. I don't think an aneroid would produce those types of acceleration problems but that is slightly above my pay grade so unsure about that one. Seems like it has to do with once it heats up everything gets warm(hot) that the problems happens. It that correct?

Coole engine down overnight and problem does not surface until warmed up again the next day?

[GeoDoc]

Was this problem ever solved? I am having the same issue with port not spooiing as fast as starboard and still reaching WOT same as starboard.

[ReelMagic]

Yes...Changed the Racor's fuel filters and all OK

[Folkvord]

Had this happen to my 2004 44 Sovran.-Stb QSM11 very slow to spool up.-It was the Boost Sensor.-Very easy to replace.