Snolab

I have a 69 Holiday Coupe 400 /442 with a fuel pump that has the vent blocked both on the pump and the return line. Just putting the engine back after rebuild. Was the vented OEM on a 400 in 69? Only "correct" part comes up as non vented. Since mine are plugged what should I do? Replace with vented and vent or keep lines blocked and replace with non-vented pump? Advice appreciated. going for original.

Octania

AC car?
I believe AC / HD Cooling cars used the fuel return line
If your frame has the return line then get that type pump and hook it up properly

joe_padavano

That's not a vent. That's the fuel return line. Olds used fuel return on cars that were expected to have high underhood temps, primarily A/C and high performance cars. The system is designed to constantly circulate hot underhood fuel back to the tank to cool. This helps prevent percolation and vapor lock. It's even more important to have this system operating now, with the cat pi$$ that passed for gasoline today.

Snolab

Thank Joe, By the way this is a non-a/c car. would you have any guess as to why someone might disconnect it? The line is cut and does have both ends blocked so nothing was returning, and it seemed to run fine before I pulled it although I never drove far. IS the pump with the return line the same as is used on the 455 model?

rcorrigan5

My first car was a '69 4-4-2 holiday coupe. When it was about 8 years old, it started to lose power drastically on any kind of incline. I took it to a shop and they did to mine exactly what you see with yours - cut the return line and blocked it off. It solved the problem but in what I would now say is a sort of "half vast" way! Somehow, the return line was pulling gas away from the engine and sending it back to the gas tank.


Randy C.

Octania

The "fully vast" fix would be to have properly functioning factory type parts in there. When they left the factory they did not have power loss going up hills.

The PN manuals should show what exact pump your car should have. And what other models use that unit. Are you going for NOS GM parts only, or whatever the parts store has, or what?

In restoring the '66 442 a while back, we could not find an NOS pump so the parts store unit was used. In order to make it look like the original, I copied the "AC" logo and the tiny "40023" or whatever PN boss off the original and applied them to the new pump.

2Olds4U

Maybe there's another reason for this.
Was the tank ever replaced? Does it have the return nipple on it?
Possibly the return line rotted out and this was somebody's idea of a fix.
Maybe somebody thought it was using too much gas and would use less if they blocked off one line.

Snolab

Only pump with a return line was listed only for a 455. Does the 400 use this? My car is a non A/C car. I started it witht the vent in place it ran for about 3 minutes and keeps shutting off like I turmed the key off. Any thought to if the vent would cause this. I have no idea if the vented pump is original or a sketchy replacement. Ther is a line from the tank but again it may not be original either. Thoughts ideas? Not sure why it would cut off.