Mercruiser 3.0LX Stalling, Sputtering?!

CPro

Seaman
Joined
Apr 29, 2007
Messages
72
Hey guys, I just found this forum and I am hoping that someone may be able to help me out.

I have a 1997 Mercruiser 3.0 LX/ 19' Sea pro that we just bought last year. I'm new to boat ownership, and as such I left a 1/2 of a tank of gas in the boat over the winter...and of course I did not treat it (won't do that again!). I did run it a few times over the winter, just to keep things moving..and it seemed to run OK>

I tried to run the boat for the first time this year last week. Last Saturday it would not run above about 2000 RPM. If you leaned on it, it would backfire, and eventually bog down and stall. It started easily back then. Additionally, there was a good bit of white smoke/steam coming out of the exhaust at that point.

In the past week, I have replaced the plugs, plug wires, distributor cap & rotor, ignition control module, ignition coil, fuel filter on the carb, fuel filter in the fuel pump, and rebuilt the carburetor. In addition, I siphoned out as much gas as I could twice, in order to try to get rid of any bad gas that may be in there. The first time I siphoned, the last 3 gallons or so had little orange globs in it. I then added more gas and siphoned as much as I could once again..the end result is that the gas doesn't look near as bad as it did.

Unfortunately, the boat is still running poorly. It is now harder to start than it was (I did mess with the mixture some though) but it will run at up to about 2500 RPM...but no more. If you lean on it, it just doesn't accelerate. It also still backfires and generally does not run strong. It doesn't make near as much white exhaust smoke/steam as it was before.

Could this be a fuel pump? That's about the only thing that I feel competent to replace that I have not replaced yet. Rockfish season just opened up last weekend and I am dying to get this thing fixed up and fishin'!

Thanks in advance for any advice,
Trev
 

b0mbtrack

Petty Officer 1st Class
Joined
Mar 26, 2007
Messages
269
Re: Mercruiser 3.0LX Stalling, Sputtering?!

the only thing left fuel related would be the fuel lines and vent for the tank. making sure they aren't clogged.
 

Bondo

Moderator
Staff member
Joined
Apr 17, 2002
Messages
71,082
Re: Mercruiser 3.0LX Stalling, Sputtering?!

Ayuh,......

It's most likely still a Fuel Issue,........

The Fuel Pump needs to deliver 4/6psi to the Carb......

And,..... What did the Insides of the Carb look like,..??...

Carb Kits are, At Best a 50/ 50 Shot......... You might Still have internal Carb Issues......
 

ziggy

Admiral
Joined
Jun 30, 2004
Messages
7,473
Re: Mercruiser 3.0LX Stalling, Sputtering?!

the last 3 gallons or so had little orange globs in it

a 1/2 of a tank of gas in the boat over the winter

neither of those things can be good. i think i'd go right to an aux. fuel tank to eliminate any possible fuel issue prior to the fuel pump....if it straightens up, ya'll know where to start looking at.....if ya got a water seperator ya might check that again + the fuel filters again...orange globs just don't sound good to me and a half tank of fuel seems like it'd premote condensation........
 

Coors

Captain
Joined
Dec 8, 2006
Messages
3,367
Re: Mercruiser 3.0LX Stalling, Sputtering?!

orange globs are rust and water
 

sabastianunf

Petty Officer 1st Class
Joined
Jun 11, 2004
Messages
215
Re: Mercruiser 3.0LX Stalling, Sputtering?!

Did you replace the fuel filters before or after you drained the fuel. The new ones may be clogged again if you ran more rust through them.
 

CPro

Seaman
Joined
Apr 29, 2007
Messages
72
Re: Mercruiser 3.0LX Stalling, Sputtering?!

I replaced the fuel filters before getting all the gas out. I suppose it couldn't hurt to replace these again..

When I opened the carb up there was some stuff in the float bowl that looked like grains of sand, but had the consistency of jelly (if you pressed on them they would just smash and offered no resistance).

One other thing is that the boat will now rev pretty strong while in Neutral, but won't go over 2500 while in gear. It still backfires while in gear and the carb doesn't look dry...it looks pretty wet with gas.

The boat has under 120 hrs on it...reportedly the first owner hardly ever used it due to medical problems...the second guy used it a fair amount...and I'm the 3rd guy in it.
 

Bondo

Moderator
Staff member
Joined
Apr 17, 2002
Messages
71,082
Re: Mercruiser 3.0LX Stalling, Sputtering?!

One other thing is that the boat will now rev pretty strong while in Neutral, but won't go over 2500 while in gear. It still backfires while in gear and the carb doesn't look dry...it looks pretty wet with gas.

How fast it'll Rev in Neutral is Absolutely,+ Totally Irrelevant........
That motor running on 2 cylinders will Rev to the Moon,+ Still Not make any Power..........

You're fighting a Fuel Delivery Issue,........ I'd tear into the Carb again,.....
Maybe you missed a small fuel passage or something.......
 
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