Mercruiser 165 fuel pump vent line to carb

[marvinjansen]

I have an older 1973 165hp with the original mechanical fuel pump. I bought a newer marine type pump with the safety vent to the carb. Problem is my carb doesn't seem to have the fitting that the newer carbs have. Is there a way to safely vent the fuel pump like into the air breather or?

 

[ziggy]

Re: Mercruiser 165 fuel pump vent line to carb

way to go mj.
your ahead of me now....

this should be a pic of your carb. a rochecster 2gc.

this ones off a '72 165 L6. it's the one i'm running on my '75 right now. see the brass fitting. that's where i'd hook up my sight line from the fuel pump to..

my '75 has a plug in this hole. so the threaded hole should be there...

 

[fishrdan]

Re: Mercruiser 165 fuel pump vent line to carb

I had the same situation, 73 140HP and a newer fuel pump with the overflow/vent line. There was no provision on the carb or flame arrestor for the line. I spliced into the valve cover to carb breather line with a T fitting, it's a down hill run and if the fuel pump ruptures and starts leaking fuel into line, it's going to get sucked into the carb. The only problem with this is, there is a small possibility for the fuel to be dumped into the valve cover breather, but I think it's a low possibility since the carb is always pulling on that vent line.

Oh yeah, I plumbed the fuel pump vent line in at an angle going downward into the T fitting, so oil from the valve cover breather didn't flow into the line and slowly fill it up.

 

[fishrdan]

Re: Mercruiser 165 fuel pump vent line to carb

Good pic there Ziggy.

That's the port I used, though on my 140, the valve cover breather also goes to that port. So I had to use a T fitting, or should I say a T fitting with 2 big ends and 1 small end.

 

[ziggy]

Re: Mercruiser 165 fuel pump vent line to carb

Good pic there Ziggy.

thanks, i took pics when i did my carb. rebuild in case i forgot how to put it back together again.. :facepalm:

fd is right. his discription is correct. my '72 had a filter breather type oil cap on the valve cover, the valve cover had a hole in it that lead directly to the port on the carb in my first response. somewhere between '72 and '75 the hole in the valve cover was put on top of the valve cover and a crankcase (not pcv) fitting stuffed in the hole.

ya can just see the fitting behind the fa to the left.

they added a fitting that's screwed onto the fa for the hose to go to.

this would be how the oem did the change. the sight tube still wasn't in use yet for the fuel pump. i believe it came into play in '78. s/m 3 i think makes reference to when the sight tube was added to the fuel pump.

 

[marvinjansen]

Re: Mercruiser 165 fuel pump vent line to carb

I will go look at my carb and see if there is a plug where that 72 carb has a fitting. I will go tomorrow after it quits snowing like crazy. This is Alabama and we are not used to this white stuff.