3.7 mercruiser runnin REAl rough...

[ericcarr2000]

Ok, I just got back from takin her, and the inlaws, out on the water. Can any one give me any hints on the problem im havin. Now, she seems to idle kinda rough, but when you get on her, shes runnin REAL rough. When I pull the plugs, theyre covered in a black soot like substance, could this be from running too rich? Im thinkin I might need a new carb. This was the one I took off of my previous motor, now on a rebuilt one. The thing ran great for the past few weekends in a row, dam marine fuel, lol.
Any who, any help out there would be greately appreciated....

 

[ericcarr2000]

Re: 3.7 mercruiser runnin REAl rough...

Ok, I just got back from takin her, and the inlaws, out on the water. Can any one give me any hints on the problem im havin. Now, she seems to idle kinda rough, but when you get on her, shes runnin REAL rough. When I pull the plugs, theyre covered in a black soot like substance, could this be from running too rich? Im thinkin I might need a new carb. This was the one I took off of my previous motor, now on a rebuilt one. The thing ran great for the past few weekends in a row, dam marine fuel, lol.
Any who, any help out there would be greately appreciated....

Also, when you dop get on her, theres a REAL strong odor of fuel...

 

[Bifflefan]

Re: 3.7 mercruiser runnin REAl rough...

Soot on the plugs can be 2 things, one is to rich, the other is not enough spark.
If the points, cap, rotor, wires, and so on are good, then id go with a carb overhaul. No real need for a new one, just fix the one have and save the extra money for gas and beer.

 

[Eric 3.7LX Alpha 1]

Re: 3.7 mercruiser runnin REAl rough...

I agree...

What year engine and is it a 2 or 4 barrel carb? What year is the carb off of?

 

[Don S]

Re: 3.7 mercruiser runnin REAl rough...

Does the choke open up when it warms up or is it staying closed and flooding the engine at all speeds?

 

[ericcarr2000]

Re: 3.7 mercruiser runnin REAl rough...

I agree...

What year engine and is it a 2 or 4 barrel carb? What year is the carb off of?

The engine is in replace of a 87 merc. I just recently installed a remanufactured one in her. She does have a new distributor also. Its a 2 barrell carb, and im assuming the carburetor is still from the 7 engine...

 

[ericcarr2000]

Re: 3.7 mercruiser runnin REAl rough...

Does the choke open up when it warms up or is it staying closed and flooding the engine at all speeds?

Hi Don, the choke is opening up..

 

[Don S]

Re: 3.7 mercruiser runnin REAl rough...

Pull the flame arrester off the carb and watch while the engine is running and see if any gas is coming out of the clear hose that goes to the fuel pump.

 

[ericcarr2000]

Re: 3.7 mercruiser runnin REAl rough...

Pull the flame arrester off the carb and watch while the engine is running and see if any gas is coming out of the clear hose that goes to the fuel pump.

You talking about the line that goes from the pump to the carb rite?"

 

[Eric 3.7LX Alpha 1]

Re: 3.7 mercruiser runnin REAl rough...

You talking about the line that goes from the pump to the carb rite?"

yes thats the one

 

[Don S]

Re: 3.7 mercruiser runnin REAl rough...

The CLEAR HOSE, not the metal line ........... the metal one better have fuel in it.

 

[ericcarr2000]

Re: 3.7 mercruiser runnin REAl rough...

Yes If i recall, there was gas going to the carb...

 

[ericcarr2000]

Re: 3.7 mercruiser runnin REAl rough...

The CLEAR HOSE, not the metal line ........... the metal one better have fuel in it.

lol...Don, youre talking about the small hose that runs from the pump up between the intake and the block to the carfb then correct?
What does this line do?

 

[Don S]

Re: 3.7 mercruiser runnin REAl rough...

Yes.

 

[ericcarr2000]

Re: 3.7 mercruiser runnin REAl rough...

Yes.

Whats the purpose of this line?

 

[Don S]

Re: 3.7 mercruiser runnin REAl rough...

If the diaphram inside the fuel pump gets a hole in it, the fuel would be pumped to the carb instead of in the bilge. In an automotive fuel pump, there is just a hole in the pump so the fuel will run out on the ground. On a boat, that gas sets very close to many things that if also automotive, could ignite the fumes and bingo..... Explosion and fire.

 

[ericcarr2000]

Re: 3.7 mercruiser runnin REAl rough...

If the diaphram inside the fuel pump gets a hole in it, the fuel would be pumped to the carb instead of in the bilge. In an automotive fuel pump, there is just a hole in the pump so the fuel will run out on the ground. On a boat, that gas sets very close to many things that if also automotive, could ignite the fumes and bingo..... Explosion and fire.

So what youre saying is if I have gas going up through this tube to the carb, then I have a hole in the diaphram in the fuel pump then rite?
The hose itself is kinda discolored so can I simply just disconnect it and see if gas comes from it that way?

 

[Don S]

Re: 3.7 mercruiser runnin REAl rough...

Sure, if you want to. Those hoses are always discolored. It's going to take more than a drop or two to make any difference in how the engine runs. So be careful.

 

[ericcarr2000]

Re: 3.7 mercruiser runnin REAl rough...

Ok Im on my way up there to the marina in a minute to check it out. Ill let you know when I get back in a couple hours..

 

[ericcarr2000]

Re: 3.7 mercruiser runnin REAl rough...

Ok I just got back from the marina, theres nothing coming out of this line, also, to top it all off, now, it wont even start now...