Fuel pumps

[Security guy]

Educate me! I've got a '71 1/2 ton with a 402 thats not original to the truck. I got a replacement fuel pump for a 402 and its got the extra port for a return line. My gas tank don't have a place for a return line so I assume its been changed to a '72 (I think). Can I get a fuel pump without the return line? The problem is that this motor was in my dads truck and he never could get it to run because it kept filling the crankcase with gas. He had the return line blocked off. Are these pumps 'high volume' that it requires a return line? Is the pumps without a return line a lower pressure than the pumps with a return line? I'm trying to find out if its cheaper to find a pump without a return line, or try to drill a hole in the tank to add a fitting for a return line. I've also thought about putting a 'tee' in the feed line but that might cause some problems. Anybody know about this?

[Longhorn Man]

get a pump for a 68 - 70.

[budman k20]

I agree that Longhorn man's suggestion should work for you. I have a 72 C-10 and a 72 K-20 the C has the three line fuel pump and the K has a 2 line... both stock. So another option would be to order one for a 72 K-20! Hope that helps. The three line fuel pump re-circulates the fuel back to the tank (in the third line) so that may explain the excess fuel in your dads engine!

[Security guy]

Looks like i'll be getting me a different pump. Is one a high pressure so that it requires a return line or whats GM's logic behind this? If it doesn't have a return line, do I need a regulator or does it self regulate? Just trying to understand how this works. Thanks.

[dwcsr]

The 2 line is a lower pressure pump and as you guessed the 3 line had about 2 lbs higher so it would circulate the gas back to the tank and help stop vapor lock, It didn't work very well and caused more trouble than it helped. The oil companies stopped the vapor lock problem.