Mercruiser 3.0??.at my wits end

CaptDuck

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May 29, 2012
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39
I have a 2000 Trophy 2052FD with a Mercruiser 3.0. The engine serial number is L634839. I am having major issues with this motor. Sometimes she will fire right up and other times it will take a while and a lot of pumping of the throttle to fire up. When it does start she will either idle just fine or she will have a hard time staying on. IF she idles good when i go to put it in gear. It will run fine for about 20 yards and then start to fall flat on its face. I have to feather the throttle to try and keep it started. She backfires quite a bit. But it won't be long before it turns off. It will turn right back on and other times it will take me a while to get it started back up. I have done the following to it: new gas, cleaned the fuel tank out, new water/fuel separator filter, new fuel filter in fuel pump, rebut carb, new spark plugs and wires and new distributor cap and rotor.
Could it be out of time? Bad coil or pick up coil? Cracked distributor cap? Bad fuel pump.

Any help would be appreciated before i decide to get rid to this thing. On a side note. This boat sat for about 3 years.
 

Bondo

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I have a 2000 Trophy 2052FD with a Mercruiser 3.0. The engine serial number is L634839. I am having major issues with this motor. Sometimes she will fire right up and other times it will take a while and a lot of pumping of the throttle to fire up. When it does start she will either idle just fine or she will have a hard time staying on. IF she idles good when i go to put it in gear. It will run fine for about 20 yards and then start to fall flat on its face. I have to feather the throttle to try and keep it started. She backfires quite a bit. But it won't be long before it turns off. It will turn right back on and other times it will take me a while to get it started back up. I have done the following to it: new gas, cleaned the fuel tank out, new water/fuel separator filter, new fuel filter in fuel pump, rebut carb, new spark plugs and wires and new distributor cap and rotor.
Could it be out of time? Bad coil or pick up coil? Cracked distributor cap? Bad fuel pump.

Any help would be appreciated before i decide to get rid to this thing. On a side note. This boat sat for about 3 years.

Ayuh,.... Welcome Aboard,..... It sure sounds like it's starvin' for gas,....
 

CaptDuck

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May 29, 2012
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I took the carb back off and cleaned it again. The filter in the carb was all clogged with crap/ Looked like sawdust, but it wasn't. not sure what it was. I smoked the carb in mu ultrasonic cleaner and cleaned it real good. Put it back together and verified the float settings were good. Got it all back together and installed. I changed the water/fuel separator filter again and she was full of water. Made sure the hose clamps were nice and tight and cleaned the fuel pump filter again. So after all this i took it out and tested it. She ran good for about 15 minutes or and then she started to bog down again. But the engine never turned off. I found a few issues when i had the carb off. My gas cap o-ring is no good (possible water leaking in from here) the choke setting on the carb was set all the way to lean, carb gasket on bottom was ripped, and water in the filter, and gunk in the carb itself. Was hoping all the things i fixed would have corrected the problem. IT work for a short time. However in those 15 minutes that she was running, i never could get WOT above 3700 RPM's. Could a bad ignition coil be causing the problems i am having?
 

alldodge

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First post
new gas, cleaned the fuel tank out
Third post
I changed the water/fuel separator filter again and she was full of water.

Not going above 3700 rpm sounds again as Bondo stated as carb problem and running out of fuel. Cleaning the tank out and still finding water in your filter you have a bad leak allowing water in the tank.
 

CaptDuck

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I put on a new water/fuel separator filter before i took it out today. Going to go and drain it and see what it looks like. I know i found a water leak from my gas filler cap. The o-ring was gone.
 

Bondo

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Ayuh,..... Hook up a remote tank of fresh clean gas, directly to the fuel pump, 'n try it,....

Sounds like the tank, 'n what's in it is the real problem,....

Unfortunately, you've probably filled all the places ya cleaned, with More crap testin' it,....

Ya also oughta mount a canister type fuel filter before the fuel pump,...

It'll hold more crud before it plugs, 'n it's a great diagnostic tool,....
 

CaptDuck

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I am working on trying to get a remote tank to test it with. Define a canister type fuel filter? You mean other than a spin on water/fuel separator filter?
 

CaptDuck

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May 29, 2012
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It does have a spin on filter. I am thinking of getting a better razor system. Also i did clean the air vent for gas tank. It was a little hard to blow air through it. Much better now and a new vent. Also have a portable tank to test it with. Sucked some more gas from tank and got some crud out if. And am probably going to test my ignition could and oil pressure sending unit. Pressure stays at 40psi.
 

CaptDuck

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Another thing is that the carb drips gas down the throat for about a minute after i shut it down. Think this is also causing problems and hard starts after shut down.
 

CaptDuck

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I think and hope i finally got it worked out. I will test it out in the next few days. I took my carb off again and verified my float was good and the setting were correct. They were off a little. So corrected that and verified everything else in carb was still good. So basically another rebuild. I also took off my air vent hose for my tank and blew it out to get out anything that might have been in there, Installed a new air vent on the side of the boat and a new anti-syphon valve on my tank. She cranks right up now and purrs like a kitten. I don't even have to give it gas before starting now. Also before when i would shut down, it was dieseling and constant drip of gas in the carb from the venturi tubes down to the throat. That is gone as well. Turn off the key and she shuts down. As another step i also replaced the water/fuel separator filter and cleaned out my tank for good measure. No water in the filter this time. So hopefully i have it fixed and i can start to enjoy this boat, It has been trying my patience thats for sure!!!!
 

Scott Danforth

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if the carb drips fuel after shutdown, your float setting is off, or the needle and seat are bad.

hopefully your fixes take care of it.
 

CaptDuck

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I took it out on the bay today. And she ran good. Didn't have the problems like i was having before. So that is good. Just got to check a few things out. I was doing 4100 WOT and doing about 21mph. I know this Trophy 2052FD is heavy. But was hoping for a lil more speed than that. I am going to put on a different prop, currently has a 15x17 prop. I have a 14.5x19 from my other boat that i will put on and see what it does. I also broke my belt today so i had to head back in. I am also going to check the timing and compression. Just to make sure it is all good.
 

Rick Stephens

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You should not go up in pitch. You were not able to reach full RPM with the 17, with a 19 you won't get past 3900 and will load up your motor worse yet. Heavy boat might need a 15 inch.
 

fishrdan

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Agree with Rick, 19P will make things worse, try a 15P prop. With a 15P prop the engine should be turning around 4500RPM, and just into the 4400-4800 RPM WOT range.

(That's a LOT of boat for a 3.0L...)
 

CaptDuck

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Thanks for the suggestions. I will get a 15 pitch prop and try that. I agree it is a lot of boat for a 3.0. I can't believe trophy would put a 3.0 in this heavy boat. I am also going to clean the bottom. It has a lot of barnacle husks
 

Bondo

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It has a lot of barnacle husks

Ayuh,.... Odds are, That's a major part of yer problem,....

Very little sealife causes big issues,...
 

CaptDuck

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May 29, 2012
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I agree Bondo. Going to be spending most of the weekend cleaning the hull and working on my trailer. And also be going out on my 19ft byliner and enjoy a little bit of the weekend. Yeah my dad who owned this boat and left it in the water for a little while. She had major barnacles on it. They were power washed off, but the husks still remained. At least now they are dry and should be easier to come off. Going to clean it as best as i can and scrape off al that i can. If i have to i will do some light sanding to get them off. I know these are another part of the problem. But at least now i have the engine running good.
 

Scott Danforth

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try sno bowl toilet cleaner on them
 

CaptDuck

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May 29, 2012
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Well i got under the boat and did some scraping off of the husks. Holy cow i didn't realize there was that many. i will be under there for a few days doing this. There is a lot of them. I scraped some off and could feel a big difference in the smoothness of the hull. I actually picked up something called bar keepers friend which is oxalic acid and she is cleaning it good. Got the trailer wrapped up real good with heavy duty contractor trash bags and taped up. since it is acid. I did a test area and it cleaned up nicely. Of course i rinsed it really good. Hopefully this will make a difference on the water, which i am sure it will. I know on my 100 foot work boat, i can tell when it is time to get hauled out and the boat scraped. I lose speed big time. But that is a much more detailed process of pulling that thing out of the water.
 
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