Cummins qsc 540 issue

[creid213]

Had an issue saturday after i had been out of a short run to cove out. After we coved out for a few hours I could not get my port engine to reach full rpm's on the way home. She would hit about 1500 and bogg down. Fuel flow shot up to 40gph and is normally around 22 at normal cruise per engine. Once back to the marina i took my neighbor out with me (who is a diesel guy by trade) and of course it ran fine. However the next morning ran into the same problem..... Let her sit for a day and went out lastnight and took off the air filter, and once again ran fine.:huh:

As far as i can tell it was eaither a fuel filter, air filter or computer issue?

thoughts?

 

[Alex F]

How's your water intake? We pickup eelgrass very often in our waters and it affects performance immidiatelly. If I get huge chunk of that grass on my scoopstrainer the boat won't even plane.

 

[AKBASSKING]

sticky injector? Any smoke associated with it?

 

[creid213]

water intake is fine, engine was running cool. just burning too much gas.... here are my thoughts of possiblities...

I am however not sure all of these possibilities would be something that would come and go unexpectedly.

-Fuel filter malfunctioning allowing too much fuel to the engine. However we changed the racor’s 3 weeks ago.
-Computer glitch, but there are infinite possibilities to that.
-Sticky injector or bad injector? The engine had 400 hours on her and a bad injector wouldn’t just come and go.
-Moisture getting into the air filter. This seemed the most plausible scenario as many diesel boats in my area have encountered this problem due to the humidity in Missouri this time of year. I run all the AC units when im on the boat and the cockpit ac is adjacent to the engine room even. I did notice the hull had accumulated a noticeable amount of condensation when the boat sat in port this weekend. This would most definitely be an issue that would come and go unexpectedly as the filter would dry out. I would also think this would add up to the increased fuel flow as the engine wouldn’t be getting the proper amount of air mixed with the fuel.

 

[fwebster]

Not the fuel filter.........the engine would stall without black smoke if it were clogged.
Sticky injector? ....not likely, unless your fuel filters are passing sludge, hence, not likely.
Moisture in the air filter due to humid air? Again not likely or all us guys in Florida would be up a creek.

You most likely need to get Cummins to re-flash the computer or reset it to default settings. An intermittant hesitation is rare on diesels unless they are electronic and this isn't he first QSC with this problem or with hard starting.

 

[creid213]

I wouldnt call it a "hesitation" as the engine will not even come up to enough rpm to gain any boost. Im stuck at idle speed until the gremlin decides on its own to go away.

 

[Robski97]

How about a bad injector. The QSC 500's had a super secret recall on the harness then the injectors.
I had an issue with fluctuating RPMS . was bad injector but was so intermittent. They finally caught it after a few sea trials.

Rob

 

[creid213]

I'm gonna dig into her this afternoon. When she does act up its as if the turbo isnt loading up at all when in gear. Thus im gonna start with the filter and hoses first. This is my first diesel boat and everyone ive talked to tells me a lose or cracked hose is the most common in this situation. Thought i checked em all before but may have missed something. The nearest cummins tech is more than an hour away so its kinda a pain in the rear get him to just "swing by" and plug the labtop in.