Mercruiser 3.0 Fuel Leak

keifermj

Seaman Apprentice
Joined
May 11, 2009
Messages
37
I have a 1986 Mercruiser 3.0 140 engine. I had it out over the weekend and I started to smell fuel. I took a look and saw gas dripping where the fuel line enters the carb (see the attached pic). When I got the boat home I decided to try to take it appart to see what the problem was. When I tried to loosen the fuel inlet nut the fuel hose started to crimp. No matter what I tried I could not get that to loosen without the fuel line turning along with it. Is there any secret to getting this off? Based on what you see with the fuel line, should I replace this? If so, is there a place that could supply the fuel line as a drop in replacement without me having to do the bending myself. Thanks in advance for the help.
 

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fat fanny

Lieutenant Commander
Joined
Feb 9, 2006
Messages
1,935
Re: Mercruiser 3.0 Fuel Leak

The point your @ right now is to hack saw the line in a place that you can eighter place a compression fitting in the line (not advisable) or to remove the fitting with vise grips and replace the fitting and line find a shop or auto parts store to match the line and fittings from the pump to the carb and bend you a new one after removing the line and fitting from carb check to ensure the threads aren't crossed that male brass fitting is toast and what happened is that someone tightened one end completely before connecting both ends and then tightening. Best advise would be to remove the line completely and replace it.
 

Bt Doctur

Supreme Mariner
Joined
Aug 29, 2004
Messages
19,345
Re: Mercruiser 3.0 Fuel Leak

you need a tubing bender
steel brake line tubing
a double flaring kit
fine file
tubing cutter
and some patience
 

mkast

Lieutenant Commander
Joined
Nov 6, 2002
Messages
1,934
Re: Mercruiser 3.0 Fuel Leak

The metal fuel line appears to be over torqued, twisted at the B nut.
Replacement is in order.
Before you start chopping the line apart, ask yourself, why the original installation was with a metal FUEL line?
 

keifermj

Seaman Apprentice
Joined
May 11, 2009
Messages
37
Re: Mercruiser 3.0 Fuel Leak

Ok. I think I found a place where I can order a replacement fuel line from that will be a drop in replacement. The problem is that I guess there are two possibilities for a 1986 Merc 3.0 140. He asked me if the fuel pump is pointed up or down. This may be a stupid question, but how do I know which direction it is pointed?
 

ken_23434

Petty Officer 1st Class
Joined
Jul 28, 2008
Messages
313
Re: Mercruiser 3.0 Fuel Leak

The fuel pump has a "dome" that houses the fuel filter. One style of the pump had the dome up and the other has the dome going down.

The fuel line exits on opposite sides from each other depending on the pump.

It's not a matter of the pump actually being installed upside down, just 2 different styles.

If you pull up the diagram for the system that some sites use to help identify the system, you can click on the 2 different types of pumps and get a pretty good drawing of them.
 

Jarvis73

Cadet
Joined
May 30, 2019
Messages
6
Ok thx. I was able to get hold of the manual, and it is pointed up, which matches the photo I took (not sure if you can see the pics I posted). I think someone else has worked on this motor and changed a few things around, so to play it safe I think I am going to get the universal A-1 rubber line. Looks like it might be a better idea. Thanks again.
 
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