fuel pump question

[spanky55amg]

The fuel pump I just took off has an inlet and outlet. The fuel pump AZ has three connections. One looks like a vacuum hose connection.

which is correct?
Why is there a vacuum connection?
can i use this one, if now what should I put on?

 

[spanky55amg]

On some quick research, the one that I have on the truck looks like it might be for a 2nd gen or early square body.

if so, why the vacuum port?

 

[spanky55amg]

So maybe its vapor return? **** it, Im going back to AZ and getting one without the vapor return.

 

[Honky Kong jr]

So maybe its vapor return? **** it, Im going back to AZ and getting one without the vapor return.

 

[spanky55amg]

As per one of the Chevelle sites, usually AC vehicles came with a vapor return. The return is too small, .060" for liquid to come out and only vapor to come out. They also put them on vehicles that needed the return if they had a lot of vapor lock. Seems like plenty of guys are running this style without the return with no issues. They capped it off. So thats what Im going to do I guess. Meh.

 

[spanky55amg]

If I didnt need it on the road in like an hour, Id deal with it... what was the saying about necessity and ingenuity?

 

[jake wells]

put a hose on the vapor return and plug the end with a screw or bolt.

 

[spanky55amg]

Even better. The old pump must have been an old rebuild able pump. I'll take a pic of it tomorrow. So the fittings to it were smaller. Funny because at one time, I was just going to order a replacement hard line from the pump to the carb but that wouldn't have fit. So I had to run to AZ anyways and just swapped them out a fuel pump for a 72 C10 w/out AC. And it was a two port. But I still had to buy a 3/8 npt transmission cooler nipple. Oh well. Job done.

 

[jamba]

What about just opposite situation? I just got new mechanical fuel pump, it has 2 connections. The one i have on side of 305 has 3 connections. Can i just ignore that return line?

 

[82sbshortbed]

My 82 c10 has 3 also. I have saddle tanks on it. So I'm pretty sure it's got one intake for each tank and then one outlet to the carb that the hard line is hooked up to. It's the one closest to the engine.

 

[1987 GMC Jimmy]

What about just opposite situation? I just got new mechanical fuel pump, it has 2 connections. The one i have on side of 305 has 3 connections. Can i just ignore that return line?

You should be fine if you plug the line and the pump nipple. I’d say try to get the correct one, but I imagine it’s not always that easy to get parts over there.

 

[PrairieDrifter]

My 82 c10 has 3 also. I have saddle tanks on it. So I'm pretty sure it's got one intake for each tank and then one outlet to the carb that the hard line is hooked up to. It's the one closest to the engine.

If I’m not mistaken I believe only one of those is an inlet, one is up to the carb and one is a vapor line. On dual tank setups I believe the two tanks go into the diverter valve separately and then a single line comes out of the diverter and goes to the fuel pump.

My suburban has two nipples, one for the inlet, one for the vapor, then it has one threaded hole for the hardline up to the carb.

 

[jamba]

You should be fine if you plug the line and the pump nipple. I’d say try to get the correct one, but I imagine it’s not always that easy to get parts over there.

Thanks! Yep, those pumps don't grow in trees here..

 

[HotRodPC]

I won't swear to it, but I think the 3 fitting pumps had the small return, and it was for a vapor return vent back to the gas tank on models before Canister Purge came about.

 

[Snoots]

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