Merc 140 fuel pump install, no ros?

[SternDriveEd]

To Buzzsaw, the fitting you show near the bottom of the carburetor is for Manifold Vacuum. You can prove this by feeling suction at the fitting when the engine is idling. It’s not for the vent line that we’re all talking about. It was typically used in cars for supplying engine vacuum to the dashboard heater controls to operate the blend doors. Sometimes it was used to control timing advance on the distributor.

 

[Alumarine]

For the OP my 1974 mercruiser 140 with serial 3774544 has the vent line.

 

[MaxGlide]

For the OP my 1974 mercruiser 140 with serial 3774544 has the vent line.

That’s great to know! Does it go where I figure it should?

 

[Alumarine]

That’s great to know! Does it go where I figure it should?

Yes, the vent line goes where that plug is on yours.
Careful installing the hose barb as there is not much meat where the threads are.

 

[MaxGlide]

Yes, the vent line goes where that plug is on yours.
Careful installing the hose barb as there is not much meat where the threads are.

thanks! will do!

 

[MaxGlide]

Got her done! $1 fitting and $4 of fuel rated line, little thread sealer on the fitting and … BOOM! Thanks fir all your help. Feel good knowing it’s done right!

 

[SternDriveEd]

Congratulations on solving the mystery of the fuel pump vent system. One last question: are you sure the clear hoses are gasoline proof? I’ve not seen clear gas resistant hose.

 

[MaxGlide]

Congratulations on solving the mystery of the fuel pump vent system. One last question: are you sure the clear hoses are gasoline proof? I’ve not seen clear gas resistant hose.

I purchased the fitting at a store that specializes in fittings and hoses. I specified it was for fuel and he assured me it was the correct hose

 

[brian3127]

It's installed upside down isn't it?

 

[Alumarine]

It's installed upside down isn't it?

If you're referring to the fuel pump that's the correct orientation for that type.
There's another style where the filter faces down.

 

[havoc_squad]

I purchased the fitting at a store that specializes in fittings and hoses. I specified it was for fuel and he assured me it was the correct hose

If you live or operate primarily in US based waters, I extremely doubt that fuel supply hose going into the fuel pump is USCG rated for inboard engine compartment fuel hose rated (type A1-15 rated hose).

I think it is required by USCG regulations that the hose has to be labeled/marked with such rating.

You might be able to keep the clear fuel hose for the return line to the carb but the clear fuel line to the fuel pump looks like a big no no.

 

[MaxGlide]

If you live or operate primarily in US based waters, I extremely doubt that fuel supply hose going into the fuel pump is USCG rated for inboard engine compartment fuel hose rated (type A1-15 rated hose).

I think it is required by USCG regulations that the hose has to be labeled/marked with such rating.

You might be able to keep the clear fuel hose for the return line to the carb but the clear fuel line to the fuel pump looks like a big no no.

Oops….good eye! I forgot to mention that the clear line you see going line going from the pump to the “tank” is strictly there for a test run while motor is out of boat. It will go to a small gas can. Actual fuel line is to code. Great catch.

 

[brian3127]

If you're referring to the fuel pump that's the correct orientation for that type.
There's another style where the filter faces down.

I must have the other style then. I did not know that.

 

[j cat]

So doing some research. It’s definitely a marine carb, parts number directs to a Rochester carb for Mercruiser. Nothing actually written about retrofitting a card pre fuel vent. Found a picture where it seems fuel vent line connects to carb and where mine simply has a bolt in it. I’ve attached pictures, first one is my carb with bolt, second pic I found with “nipple” it appears this is where the line should go?

I looked up your 140cu engine 1978 .. the carb is 2GC/2GV ...the vent line on your carb port blocked up .. put the vent connector to the hose THEN PUT ON THE VALVE COVER PORT..
fuel pump carter part#B-47585...
FUEL PRESSURE 3-6 PSI

 

[MaxGlide]

It's installed upside down isn't it?

Some are, not this year of engine!

 

[MaxGlide]

I looked up your 140cu engine 1978 .. the carb is 2GC/2GV ...the vent line on your carb port blocked up .. put the vent connector to the hose THEN PUT ON THE VALVE COVER PORT..
fuel pump carter part#B-47585...
FUEL PRESSURE 3-6 PSI

I’m sorry, I’m not following you? From the advice in here, from diagrams, photos and videos, it is now connected the way it should be.

 

[j cat]

I’m sorry, I’m not following you? From the advice in here, from diagrams, photos and videos, it is now connected the way it should be.

I have the OEM manual 1974-1978 the 140 engine has to use the vent from carb to the valve cover .
the picture of that carb vent is on the OEM manual ! his carb is plugged up on the vent port . well he or another guy changed the engine >........same carb ....

 

[SternDriveEd]

The small diameter hose that we’ve all been talking about is a fuel pump diaphragm vent hose. It connects from small fuel pump barb to small barb on the upper part of the carburetor. It provides a path for any liquid fuel that escapes the fuel pump in the event of a ruptured fuel pump diaphragm. The escaping fuel would end up in the carburetor instead of into the bilge. The tube that connects from the flame arrestor to the valve cover is for crankcase ventilation of blow by gasses. This tube is typically the diameter of a garden hose. It allows the dumping of crankcase gasses into the intake air. Hope this helps.

 

[MaxGlide]

The small diameter hose that we’ve all been talking about is a fuel pump diaphragm vent hose. It connects from small fuel pump barb to small barb on the upper part of the carburetor. It provides a path for any liquid fuel that escapes the fuel pump in the event of a ruptured fuel pump diaphragm. The escaping fuel would end up in the carburetor instead of into the bilge. The tube that connects from the flame arrestor to the valve cover is for crankcase ventilation of blow by gasses. This tube is typically the diameter of a garden hose. It allows the dumping of crankcase gasses into the intake air. Hope this helps.

Got it! Thanks!

 

[MaxGlide]

Motor update. Got it all together, did a test start with engine on stand. Started right up! Initial timIng adjustment and she purrs like a lion. Will install in boat, recheck timing at proper idle and go catch some prawns!
Thank you so much all!