Mechanical fuel pump vent?

[dukerollo]

I am about to pull the L20 out of my 79 a10 and replace it with an 80 A15. The fuel pump on the L20 has an in and and out, but rhe A15 pump has an in, an out, and what I assume to be a vent line. Since the A10 has no where to hook this to, can it just be blocked off? What are the chances that the pumps will interchange between the 2 engines? Maybe if I change the arms? This is for the beater mobile/deer slayer, so I am trying to spend $0.00 to make this thing go together.

[datzenmike]

Post a picture of the A series pump. I don't know about the third connection...  http://community.ratsun.net/topic/54932-photobucket-ratsun/

[dukerollo]

 

Just a stock photo, because I'm away from the car, but from memory, it looks similar.

[datzenmike]

Well then, where do the hoses go?

[dukerollo]

it runs back under the car along with the feed and return. I don't know if it vents into the tank or some emissions dingus or what. I haven't dropped the tank on the car to investigate.

[datzenmike]

I've seen (non Datsun) fuel filters like that. They prevent vapor lock by venting any bubbles back to the tank. 

[dukerollo]

I'm thinking that's all it is for. Hopefully someone knows for sure and will pipe up. Do you know if the L and A series pumps will interchange at all?

[datzenmike]

Think the L series has a longer arm.

[Jester]

I can't see Nissan making a change like this so late in the game with the L series being replaced soon.

 

Lay one on a piece of cardboard and trace the arm and mounting points. Lay the second one in the same spot and see what you find. I would bet they will be a direct bolt up. 

[dukerollo]

I think they do bolt up. From what I've googled and from what Mike says I may need to swap arms.

[dukerollo]

Disregard all of the above, I was misremembering things. Both the cars have fuel returns to the tank. My head must have been on fire that day, I apologize for time wasted.

[Doctor510]

I'm thinking that's all it is for. Hopefully someone knows for sure and will pipe up. Do you know if the L and A series pumps will interchange at all?

NO WAY!!!  I'd rather have a double hernia operation without anesthesia than try to change arms.  If you have an A series motor, use an A series pump!

[Stoffregen Motorsports]

Agreed. Disassembling a mechanical pump to swap out the arm is not as simple as it sounds. And at the end of the operation, you may have a leaky pump.