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Crusader 6.0L Intermittent Power

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Adam Frenzel

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I am new to the forum and was wondering if I could get some help. I have twin Crusader 6.0L fuel injected engines and am having an issue on the port side engine when it comes to power. The engine will start and run but it sounds like sometimes it is sputtering. I notice it at higher RPMs but it will run great and then I hear and feel vibration for a few minutes and then it will run fine again. When this happens, the rpm guage will drop causing the starboard side to drop as it picks up the slack of the port. Then after a minute or 5 it will go back to dropping again. I drained the fuel filter and that did not help. Plugs and wires look fine. Any idea what else it could be? It happens intermittently so I am scratching my head.
 
I would like to add some more details. This happens on and off throughout the day. Motor starts great every time. Yesterday I could hear and feel vibration in this engine and as I brought the rpms up, it went away and gave full power. I can be cruising at 4,000 rpms and not tough the throttle and just feel it losing power and also see it losing rpms on the guage. Without touching the throttle, out of nowhere it will kick back up and run beautifully. I have had this boat for three years and it has always been this way. Have changed the oil and filters every year. Checked plugs and there are no visible signs of damage. Look normal to me. Tachometer does not seem to work properly. Can plugs work intermittently? Can plug wires work intermittently? Can fuel pumps work intermittently? Any idea would be appreciated.
 
Welcome to ME.com!

Intermittents can happen in either fuel delivery or ignition.

It's always been that way??? how old is the hull? how many hours?

I'd start with a fuel pressure check...under load and idle
 
Thank you Mark. I went down today to check the plugs and wires and noticed the outgoing connection on the fuel pump assembly was loose. Would it be possible that air was getting into the fuel line causing a sporadic loss in fuel supply?
 
as you described it, I'd say NO...physics hints that any pressurized connection that becomes loose won't let any air into that connection...
 
Docksidemarineservices said:
Change the spark plugs. Make sure you use the OEM suggested plugs, don't cross reference them to a cheap plug.
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I checked the plugs and there was a small amount of residue on most of them and one had zero residue. Crusader recommends and sells specific plugs that cross over to a NGK plug, which were in the engine when I bought the boat. The wires look good but should I replace them too?
 
So you are saying if the connection was loose, it would be squirting gas out and not sucking air in? That does make sense. Do you think my issue could be an intermitten fuel pump problem?
 
Docksidemarineservices said:
Yes, install the recommended plugs.
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I’m back. I installed the recommended plugs and gapped them properly. Still having the issue. Rpms hover around 3500 rpm at full throttle but recommended cruising is at 4,000 rpms. It will stay at 3500 rpms for a few minutes then something kicks in and gives the engine, or engines, full power. A minute later, it drops back down again. This would repeat if I let it. I have had this boat for about 3 years and it has always been this way. The guy who owned it before me used it as a weekend apartment and only took it out once or twice a year. I changed the fuel filters when I bought the boat and they should be changed again. I have drained the filters though. I dont think its the filters because the engine, or engines, ran this way from the beginning. Unless they put the wrong filters in? What should I check next?
 
I just check my transmission fluid on the port engine, which was giving me the problem, and it was half a quart over max. I checked it before and after I let the engine run for a minute. It is supposed to take a max of 4.4 quarts MAX and it had 4.9 quarts. I pumped half a quart out. Now the dip stick is reading max. I am hoping to do a test run tomorrow but do you think that amount extra could cause aeration and slipping?
 
1/2 qt overfill may be enough to cause aeration but that would 'unload the engine' and the RPM would rise, not drop...

With the correct plugs, I'd still be inclined to check the fuel pressure across the RPM range...
 
makomark said:
1/2 qt overfill may be enough to cause aeration but that would 'unload the engine' and the RPM would rise, not drop...

With the correct plugs, I'd still be inclined to check the fuel pressure across the RPM range...
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Ok, I am going to check the fuel pressure. If its not fuel pressure, where do you suppose I check next?
 
I believe you said you replaced the fuel filters but did you remove and clean or replace the anti-siphon valve on the fuel line at the top of the tank? Does your boat have 1 or 2 fuel tanks? If 2, are there valves for changing the source of the fuel? Possible clogged vent on tank? Remove fuel fill cap to allow plenty of air into tank to diagnose that.
 
erich said:
I believe you said you replaced the fuel filters but did you remove and clean or replace the anti-siphon valve on the fuel line at the top of the tank? Does your boat have 1 or 2 fuel tanks? If 2, are there valves for changing the source of the fuel? Possible clogged vent on tank? Remove fuel fill cap to allow plenty of air into tank to diagnose that.
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i have not checked the antisiphon valve. Do I need to reseal that fitting when I reinstall it? There is a black sealant on it right now. Also, I noticed my starboard engine spark plug wired had been replaced with new sometime before I bought the boat but I believe the port engine wires were not. I ordered new wires and they should be here tomorrow.
 
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