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Fuel starvation issue: 2004 Captains Choice 8.1

T

tyrenta

New member
I'm having a fuel starvation issue I'm trying to track down the cause.


My port engine loses RPM after running for 15-20min under load, and the problem gets worse the longer it runs, and increasing the throttle does not result in an increase in RPM. I’ve already changed out the Racor filter had no impact. Both engines feed off the same tank so it isn't the fuel.


If it cools for 30-45min will run normal again for up to 10-15 min then same problem. The longer it runs the worse it gets. This started about 4 hours into an 6 hour/2 day run, and progressively got worse to the point where I was limited to 1200-1500 RPM for the last 10 miles or so of the run.


I haven't had a chance to run it again, so I'm not sure if the problem is worse now immediately or if the engine will again run fine after cooling. My yard mechanic told the work order manager he thinks it may be a bad coil, but I'm not sure how much info was relayed to him to make that assessment.


Any thoughts on candidates? I'm worried that since it takes some time under load for it to crop up, it won't be easy to get a diagnosis from the mechanics who have plenty of other work to do this time of year....
 
makomark said:
What about the filter In the FCC??

have you checked the fuel pressure while running??
Click to expand...

I wasnt aware there is an additional filter in fhe FCC, is it accessible? I can work my way around pretty well but don't do this for a living, so apologies for any noob questions.

I'm was planning on picking up a gauge also to check pressure this weekend. Any likely candidates, or I start there first?
 
If you go to the crusader www site, you can get the parts listing and see what serviceable parts are in the subassemblies.....

I'd be inclined to change the other filter and then do the fuel pressure check....do it under load and across the rpm band....
 
makomark said:
If you go to the crusader www site, you can get the parts listing and see what serviceable parts are in the subassemblies.....

I'd be inclined to change the other filter and then do the fuel pressure check....do it under load and across the rpm band....
Click to expand...

Thanks much — I’ve found the 115 micron filter, it’s a black disc aprox 3in diameter but does not seem very serviceable. Do you just shut off fuel and then disconnect the nuts?

there is also one inside the high pressure pump it looks like but starting with the in line filter first....
 
Update: I checked/cleaned the pancake filters -- they were fine, very small amount of tank debris assume from before I had the racors installed.

However, a few more test runs over a few days and I think I solved it -- twice after 45 minutes I started to lose RPM, and the second time I had a strange alarm situation where both engines hot water alarms went off at the same time, even though the elbow/manifold temps were fine per my heat gun. So I checked at the panel my batteries and sure enough the engine bank was below 12v.

My alternator is being bench tested now, but I assume its cooked. It wasnt something cooling off that was the fix, it was hooking to shore power to charge the engine batteries back up, or running at low RPM where the other alternator could keep up with the draw :rolleyes:...

Question: I'm going to change them anyway as they are due, but would misfires from a low voltage situation impact the plugs? Any other preventative service items I should be considering on a 13 year old / 550hr engine, such as replacing spark plug wiring, having someone with an ECM computer scan any codes, etc?
 
Low voltage can impact the entire ECU...depending upon how low it goes....good news is little chance for any damage.

Unless it happened frequently and regularly, I doubt the plugs suffered.

The owner's manual will ID the essential items....and it sure wouldn't hurt to get the ECU scanned....getting a history is always good.
 
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