1975 Corvette oem quadrajet and engine, mechanical fuel pump, new lines from tank to pump.



Vette is in storage and was just told that I have a little fuel dripping from the location of the fuel pump (rubber hose) and unable to take a look at it right now. In the meantime, I’d like to replace all the rubber lines, but can’t remember the details on how the fuel line runs.

Correct me if I’m wrong.

There were two lines that run from the tank to pump, one fuel one vapour?

A standard 1975 Corvette mechanical fuel pump has three ports for the following lines:

• Main Fuel Supply (Feed) Line: A 3/8-inch line that delivers fuel from the tank to the pump.
• Fuel Return Line: A 1/4-inch or 5/16-inch line that sends excess fuel back to the tank to prevent vapour lock.
• Pump-to-Carburetor Line: A single hard line that delivers pressurized fuel from the pump to the carburetor.

Questions based on memory.

Is there a 3/8” neoprene rubber hose that goes from the main fuel supply and fuel pump?

If the fuel line from the pump to the Q-Jet also 3/8” neoprene? I believe there is a metal line that it connects to just before the Q-jet fuel filter?

Is the return line that goes back to the tank 5/16” and is there a rubber hose somewhere?

Which line connects to the threaded female fitting on the mechanical fuel pump?

Would 4’ of neoprene line and 4 hose clamps suffice?

Can any of these rubber lines be replaced with metal?

EDIT:
I just noticed on the image I posted that both male fittings aren't the same size, assuming that's the right 75 vette mechanical pump? Sorry about the oversize image, don't know how to make it smaller.

 

The rubber lines surrounding the pump are molded. Meaning you can’t use straight fuel line in that area because it will kink. The pump to carb line should be metal, but they are commonly cut and replaced with rubber. The proper safe way would be a metal line like OEM. Here is an article about changing a fuel pump on a C3, but it has lots of good information about the fuel lines too.

 

Hello,
P gave a good description!
The preformed hoses are essential.
Here's a couple of photos which may help.
Regards....

This happens to be a 71 base motor pump.
It used a tiny tower clamp on the return line.
Later years used a typical spring clamp.

 

79 if helpful. buy the pre-formed lines.. S style..
post up some pics!

 

Piersonpie: thanks for the reply.
I appreciate, the link, it's helpful. In Canada, we have two Vette Parts Dealers, both have a 3/8" curved fuel line (1970-1982 Chevrolet Corvette Moulded Fuel Line Feed) the other 1968-1981 Chevrolet Corvette Vent Return Line Hose is a straight hose, non moulded and no size given, but I believe it's 1/4" can someone confirm. I had someone check my Vette and they stated that one line with a threaded fitting is metal and it's all metal from the Q-jet, therefore I only need to replace the two rubber lines.

Alan 71: Thanks for the reply.
Good to see you back and thanks for the photos, the visual helps.

Interpon: Thanks for the reply.
Thanks for the photos, they always help. I'm unable to post photo's as I'm out of town.

Question, is the rubber vent line return hose, 1/4" ID 1/2" OD?

 

Hello,
The supply hose is 3/8" i.d.
The return hose is 1/4" i.d.
Regards....

They are often available as a set with the proper sized spring clamps.