Carburetor Port

[62cruiserinc]

I just bought a 1981 Sea Ray with a Merc I/O with a GM 350 engine. The engine was replaced with a crate engine about 10 yrs ago according to the PO.

I was going through everything before putting the boat in the water (replacing impeller, checking bellows, etc) and noticed the following on the carburetor (Edelbrock marine carb). There is a port on the carb which is not connected. The port is shown in the picture below just to the right of the fuel inlet. It goes all the way through into the carb. It seems that there should be something connected or at least it should be plugged. Is this a PCV port that is not being used?


Thanks
Steve

 

[alldodge]

That is to connect a clear fuel line coming from a mechanical fuel pump. If the diaphragm ruptures, it will dump the gas down the carb instead of in the motor. If you have an electric fuel pump, just put a cap over it.

 

[62cruiserinc]

Thanks.

I will check to see if I have an electrical or mechanical fuel pump today when I go to the boat.

Steve

 

[62cruiserinc]

That is to connect a clear fuel line coming from a mechanical fuel pump. If the diaphragm ruptures, it will dump the gas down the carb instead of in the motor. If you have an electric fuel pump, just put a cap over it.

I checked the engine last night and it has a mechanical fuel pump.

There is a small device with a glass bowl connected to it that is plugged off. Another output from the pump goes to a large filter/water separator and then the carb. I suppose the small glass-bowl setup was the original 1981 setup and then it got plugged and replaced by the large filter when the crate engine 350 was installed about 10 years ago.

There are no "extra" places to connect a line to the carb unused port.

So do I just plug it on the carb and carry on?

Thanks
Steve

 

[Bondo]

There is a small device with a glass bowl connected to it that is plugged off.

Ayuh,.... The glass bowls disappeared back in the '70s,.....

That should be the vent line, that should go through tygon tubin' to the port on yer carb,....

 

[alldodge]

Can you post a pic?

 

[achris]

The glass bowl hanging off the side of the fuel pump is the 'diaphragm ruptured' indicator. As most people either didn't see it or ignored it, it was replaced with the 'flood the engine' tygon tubing. Kinda hard to ignore that one

My suggestion would be to pull that fuel pump off and put a later pump on, and connect the tubing from the port on the rupture side of the diaphragm to that port on the carb.

Also, the water separating filter should be before the pump, not after it. The line from the pump to the carb should be a hard (steel) line.

Chris. ...

 

[62cruiserinc]

I will try and get pictures tonight. It's a real tight squeeze down there.

Also, I may be wrong about the water separator, it might be plumbed in before the pump.

Steve

 

[62cruiserinc]

It was a real PITA to get the pictures. The engine is under the deck and the front of the engine is about a foot from the fuel tank and its a dark area. I had to take pictures using a flashlight and jam the camera against the fuel tank so I couldn't see how they looked until the picture was taken.

The water separator is before the pump.

The gas line from the tank to the water separator is a hose. The line from the separator to the pump and the line from the pump to the carb are both hard line.

Here are a couple of pictures that are the least blurry and least dark:

 

[alldodge]

The glass thing appears to be called a sight glass (item 9). Appears to be used prior to using clear tubing.

http://www.mercruiserparts.com/bam/subassembly/31737/990/30

If it was mine, I would remove the sight glass and install a barbed fitting with tubing going to the carb.

 

[62cruiserinc]

Thanks for the info!

According to the parts diagram, there are two different fuel pumps for sight glass vs vent tube. The sight glass fuel pump is NLA (no longer available).

So I assume the sight glass output on the old pumps is the same (functionally) as the vent tube output on the newer pumps?

There IS some fuel in the sight glass bowl. Maybe I should consider replacing the fuel pump since its probably the original from 36 years ago?

Summit Racing sells a Carter marine fuel pump for my engine for $59 which has the vent connection.

Steve

 

[alldodge]

Agree, they don't make them anymore and the new style will work on yours. The carter pump should work

 

[62cruiserinc]

I found the Carter pump on Rock auto for $48 and ordered it.

Where do you guys get the small piece of Tygon tubing for the vent line? Most online places I have found sell larger quantities and want a lot for shipping.

Steve

 

[achris]

I found the Carter pump on Rock auto for $48 and ordered it.

It needs to be specifically 'MARINE"... If it isn't, it won't have the rupture port fitting. It will just spew petrol into the oil pan when the diaphram gives out. Not a good look!

Where do you guys get the small piece of Tygon tubing for the vent line? Most online places I have found sell larger quantities and want a lot for shipping.

Steve

Try a scientific or medical supplies company.

Chris.....

EDIT: Couldn't find a marine fuel pump on Rockauto website anyway. Got a link?

 

[alldodge]

I don't see any reason not to use regular fuel line if your unable to find it at right price. Sure you won't be able to see the fuel in the line, but if the motor is running bad, I'm pretty sure you would be able to see it dripping

 

[62cruiserinc]

If you go to Rock Auto's web site and click on the "Part Number Search" Tab at the top, it will open a page where you can select the manufacturer (Carter) and enter the part number (M61073) and then search. The pump will come up for about $50. Using a discount code you can find online drops it by another 5% to about $48.

Steve

 

[62cruiserinc]

The new pump came today from Rock Auto:



Note there is a vent fitting to connect it to the carb.

For the vent connection, I did find some 1/4"ID clear fuel line at the local auto parts store. It's actually intended for small engines, but it must still be gasoline resistant so it should work for me.

Steve

 

[Rick Stephens]

You can still get the tygon tubing from Mercruiser. Part number #32-7381567 I found it at iBoats.

 

[Scott06]

I got Tygon tubing at NAPA, apparently it's used on lawn equipment for fuel hose

 

[62cruiserinc]

I got Tygon tubing at NAPA, apparently it's used on lawn equipment for fuel hose

I think that's the stuff I saw at an auto parts store. It was packaged in 2' lengths, which I'm not sure is long enough. I'll have to check NAPA and see if they have longer pieces.

BTW, what do you guys recommend for a gasket sealer/adhesive on the fuel pump gasket?

I know that in theory no sealer should be needed, but the pump is so hard to get at that I don't want to take any chances.

Advance Auto carries the Permatex Copper Spray-A-Gasket Hi-Temp Adhesive Sealant which some people like.

Then there are the old standbys, High-Tack and Form-a-gasket No.2.

Steve