2004 mercruiser 3.0 tks carb running rough

[fd5298]

Hi all
Have a 2004 mercruiser 3.0 liter with tks carb. Motor usually starts up ok when i first get to dock, I let it warm up to 160degrees and then take it out. After running about 10 minutes running and sounding fine the motor starts to seem slugish(takes more time to get up to speed), sounds like its bogging or flooding out(never stalls and still gets up to speed) and occasionally will "diesel" when I shut it down. Also sometimes it is hard to start when hot.
So far I have gone through the fuel tank,siphon valve, fuel lines, replaced water seperator filter,had the carb rebuilt, and replaced the plugs and wires. I also use the ethanol treatment when filling up the tank. Any other suggestions on what to look at are appreciated. thanks!

Could it be the timing? Can i use an automotive timing light?

 

[Bork]

Re: 2004 mercruiser 3.0 tks carb running rough

Hi;

I have the same engines, my starboard raises **** with me, starting has been a poblem , I have had it all done also and the same problem. Only one year out of 6+ season have I had a good year.

The dieseling is unbelieveable in this age, I talked to Merc, they said use a lower heat plug, the people who repowered said use a hotter plug. I did both same problem.

Now I have compression problems on that engine, good luck.

Tom B.

 

[kellmike626]

Re: 2004 mercruiser 3.0 tks carb running rough

For the dieseling, I had the problem too, but I find that if I have been driving the boat, and then put the gear into neutral and shut it down too quick, that's when the dieseling occurred. I have the same engine except mines a year newer.

What i do is after putting the gear into Neutral, let the engine idle for about 15-20 seconds, then shut it down. My dieseling has gone away since I tried that, so maybe give that a shot.

 

[fd5298]

Re: 2004 mercruiser 3.0 tks carb running rough

My biggest problem is the sluggishness. The engine actually sound different and the performance drops at same time. Could this possibly be a timing issue? Can I use a regular automotive timing light?

 

[JWebber]

Re: 2004 mercruiser 3.0 tks carb running rough

You can use a timing light but you have to put the engine in base timing mode. You said you changed the wires and plugs, did you also change the rotor and cap?
It's also important items when doing a tune-up.

 

[fd5298]

Re: 2004 mercruiser 3.0 tks carb running rough

This engine has electronic ignition, dont believe it has a cap and rotor?

 

[fd5298]

Re: 2004 mercruiser 3.0 tks carb running rough

bump

 

[fd5298]

Re: 2004 mercruiser 3.0 tks carb running rough

going down to marina today to check the timing and test the coil. Does this motor have a distributor cap and rotor? I dont think it does but just want to be sure. Anything else i should check while im there? Thanks for the help

 

[fd5298]

Re: 2004 mercruiser 3.0 tks carb running rough

Checked timing today and it was correct (2 adc). Motor is still doing same thing. Any ideas where to look next? I may try cleaning carb again and maybe order a new float(only part i didnt change).

 

[gizmolvr]

Re: 2004 mercruiser 3.0 tks carb running rough

ordered a new float today. I want to check the fuel pressure to see if there are any other issues. Does anyone know what is the correct fuel pressure for this motor

 

[fd5298]

Re: 2004 mercruiser 3.0 tks carb running rough

went down to boat today and checked compression. The number 2 cylinder had no compression and all the others had a reading of 165. Mechanic pulled head and found that the valve in the number 2 cylinder had tuliped causing the problem. He suspects it was caused by too much pitch on the prop. He sent out the head today to have the valve replaced and have the head machined. He stated that the other valves were fine. Anyone have a ballpark figure on what i should be paying to have this done? Thanks for all the help

 

[Bork]

Re: 2004 mercruiser 3.0 tks carb running rough

Hey;

I got charged 250.00 to do the head, 3 valves, total price, hauling, all misc., labor was 750.00

Tom