Merc 140 fuel pump install, no ros?

[MaxGlide]

1978 Mercruiser 140, serial number 3773776
Replacing my mechanical fuel pump and read a lot of references to an actuator “rod” that must up into position before installing fuel pump. I cannot find any such rod in my motor. (See pics) My engine seems to have an off round cam (?) type thing that actuates the pump as the engine rotates. Does that make sense?
Thanks in advance for your time… Wayne

 

[MaxGlide]

1978 Mercruiser 140, serial # 3773776
I think the fuel pump I’m replacing must have already been replaced. Original schematics shows fuel vent only on engines after serial # 04460665. The fuel vent was capped off like this on old one. Ran for two summers like that, guess it’s ok?

 

[SternDriveEd]

What you see is the fuel pump camshaft lobe. It is a part of the camshaft and of course turns at 1/2 engine crankshaft speed. Anyway, here’s what you need to do. Hold the new fuel pump against the mounting surface by hand. It should fit perfectly flat against the machined surface. If it doesn’t, simply bump the engine over a bit until it fits flat against the surface. Now use a little gasket sealant on the gasket and install the fuel pump. As the engine runs, the arm of the fuel pump is actuated by the eccentric lobe, pumping fuel to the carburetor. No fuel pump push rod on this application.

 

[SternDriveEd]

1978 Mercruiser 140, serial # 3773776
I think the fuel pump I’m replacing must have already been replaced. Original schematics shows fuel vent only on engines after serial # 04460665. The fuel vent was capped off like this on old one. Ran for two summers like that, guess it’s ok?

1978 Mercruiser 140, serial # 3773776
I think the fuel pump I’m replacing must have already been replaced. Original schematics shows fuel vent only on engines after serial # 04460665. The fuel vent was capped off like this on old one. Ran for two summers like that, guess it’s ok?

Look at the top of the carburetor for a similar fitting for the fuel pump vent line to attach. If the fuel pump diaphragm leaks, the fuel is sent into the carburetor instead of into the bilge. Marine fire safety.

 

[SternDriveEd]

Look at the top of the carburetor for a similar fitting. The fuel pump vent hose will send any fuel that leaks from a defective diagram up to the carburetor instead of into the bilge. Marine fire safety.

 

[achris]

...read a lot of references to an actuator “rod” that must up into position before installing fuel pump.… Wayne

That refers to V engines only. Your 4 cylinder engine has a lever on the pump that rides directly on the camshaft lobe.

And referring to your other thread, get that vent line installed!

Chris...

 

[achris]

1978 Mercruiser 140, serial # 3773776
I think the fuel pump I’m replacing must have already been replaced. Original schematics shows fuel vent only on engines after serial # 04460665. The fuel vent was capped off like this on old one. Ran for two summers like that, guess it’s ok?

Nope. A fire waiting to happen.

Check the carburetor (make sure it's not a car carb), then buy some Tygon tubing of the right diameter and run it from the vent on the bottom of the pump to the correct fitting on the carb. (run it up alongside the fuel supply line, which should be a hard pipe, not rubber hose).

Chris.........

 

[MaxGlide]

What you see is the fuel pump camshaft lobe. It is a part of the camshaft and of course turns at 1/2 engine crankshaft speed. Anyway, here’s what you need to do. Hold the new fuel pump against the mounting surface by hand. It should fit perfectly flat against the machined surface. If it doesn’t, simply bump the engine over a bit until it fits flat against the surface. Now use a little gasket sealant on the gasket and install the fuel pump. As the engine runs, the arm of the fuel pump is actuated by the eccentric lobe, pumping fuel to the carburetor. No fuel pump push rod on this application.

Thanks a bunch. that's what I figured! Will do.

 

[MaxGlide]

That refers to V engines only. Your 4 cylinder engine has a lever on the pump that rides directly on the camshaft lobe.

And referring to your other thread, get that vent line installed!

Chris...

Will do. I will have to locate where it is supposed to go on the carb as I do not see any fixture where the vent tube would attach to.

 

[MaxGlide]

Nope. A fire waiting to happen.

Check the carburetor (make sure it's not a car carb), then buy some Tygon tubing of the right diameter and run it from the vent on the bottom of the pump to the correct fitting on the carb. (run it up alongside the fuel supply line, which should be a hard pipe, not rubber hose).

Chris.........

I will have to see if it is possible to retrofit a fixture on the carb because, as it stands, there is no fixture to plug the vent tube that would come from the pump. I will study newer schematics to see where it is supposed to fit.

 

[Bt Doctur]

You fail to understand how a mechanical works.

Pumps – (Leaking Fuel):​

• Most mechanical fuel pumps, have a weep hole on the bottom side of the unit. When the internal diaphragm leaks, fuel escapes through the weep hole; to notify the vehicle owner of a malfunction. This is one of the more common fuel pump problems. Usually found on classic cars, between 30 and 60 years old. The internal rubber diaphragm is capable of lasting a long time. Gas is a petroleum product, that helps extend the life of the rubber diaphragm through lubrication.

Actually its a vent for the diaphram. it allows air to enter on the up stroke and air to exit on the down stroke , this allows the diaphram to move up and down to pump fuel. Blocking ot off prevents the fuel pump from operating correctly. Marine mechanical pumps place a barbed fitting here to transport the leaking gas from a ruptured diaphram to be directed up to the carb and not into the bilge

 

[76SeaRay]

Note that the carb fuel bowl overflow at the top of the carb also has to be directed into the throat of the carb in case it overflows.

 

[MaxGlide]

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?

 

[Scott06]

Would appear if you look at parts diagram 1A, 1B,1C that the vent was put on after your serial started at 044xx and up. https://www.marineengine.com/parts/...-5157668/fuel-pump-fuel-filter-and-carburetor

looking at the serials if you have a 03xx serial it is likely older than '79. My grandfather's 65 or 66 Penn Yan with Merc 150 IO did not have the overflow into the carb body either. Not sure what year this came into regs or common use, but I think some flame arrestors came with fuel pump rupture overflow fitting

 

[Scott06]

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?

yes put a nipple in here that's where it should go- if fuel pump diaphragm ruptures fuel gets dumped down carb vs in bilge. Will probably bee so rich it stalls...

 

[Buzzsaw420]

Rochester 2 barrel? Brass one on the bottom

 

[Bt Doctur]

THAT is the fuel line inlet

 

[MaxGlide]

Rochester 2 barrel? Brass one on the bottom

looks like the carb I have. I think I found where the nipple can be retrofitted on it. Left pic is my carb with bolt where I think nipple shoukd be. Right pic is internet shot of carb with nipple. Just gotta find the proper attachment now

 

[Buzzsaw420]

THAT is the fuel line inlet

I didn’t mean the big one on the top, the little one at the bottom that you push your clear tube on. I sort of tried to circle it. Sorry to confuse

 

[MaxGlide]

I didn’t mean the big one on the top, the little one at the bottom that you push your clear tube on. I sort of tried to circle it. Sorry to confuse

I saw your circle. My carb is a bit different but same idea