My 2021 resolution was to start bolting parts back on the car (now that the engine bay and underbody are cleaned up and painted) and I'm already making progress! One of the first things I want to reinstall and test is the fuel tank - while I've got the car on the rotisserie it's much easier to access. I'm replacing the fuel pump before reinstalling the tank, and I was hoping someone could help with a couple questions. Here's a picture of my old pump alongside the new pump:



First, the fuel sock. I've got the original sock on the left (black) and the replacement (white) that came with the pump (Walbro 255lph unit). It looks like the replacement is about half the size/surface area of the original. Is this going to cause restrictions for a mild NA 350 (L31 with the 94666492 cam)? Should I look for a replacement similar in size to the original sock, or does the material of the new sock just "flow better"? The original sock is pretty stiff and has some tears, so I don't think it should be reused.

Second, the black foam covering on the original pump (left). I assume it's some sort of insulation? It crumbled apart when I tried to remove it, but I'm uncertain whether the replacement pump needs a similar covering (it didn't come with one). My understanding is that these pumps cool themselves via immersion in the fuel, so I'm not certain why they'd have any insulation. If it's just a noise control measure I'll probably leave it out.

Finally, is there anything else I should pay attention to while I've got this apart? Fuel pump swaps are a PITA, I'd rather not drop the tank to redo this in the future. I've checked the motion of the fuel level arm, the float seems to be in good shape, the resistance on the fuel sending unit is fine and fluctuates when I move the arm, lines are clear, wiring looks fine with no obvious damage.

Thanks in advance!

 

The long sock is the "1LE special dual swinging fuel pick-up" or whatever folk-lore some jackass came up with after being told it was a redesigned sock. It's like $18-25 bucks depending where you get it. Delphi or AC Delco offer it, you can use the one that pulls up under the 1LE years, or make it easier on yourself and just look up one for a 4th gen. There's little difference between them, but you might find it easier to find the 4th gen style locally.

 

Oh yeah, almost forgot... The foam wrap is for noise isolation. The Walbro's are so loud you probably wouldn't be able to tell the difference even if it was there. Some pumps comes with the sleeve, others don't.

 

Great info, thanks! Confirmed my thinking on that foam wrap, I'm just going to leave it off. If it gets that crumbly and fragile over time, I'd rather not have that crap floating around in the tank.

Looks like this should work: Precision Fuel Pump Strainer

At $8 I might as well get it, but I'm still curious as to whether that smaller sock (or strainer) would cause a significant restriction, or if there's some other benefit to the larger size/surface area. Just for my own personal knowledge.

 

Larger sock takes up more area in the tray, which means less fuel starvation during cornering with low fuel levels in the tank. There's no good reason to use a generic sock.

 

Got it, that makes sense. I was focused on flow rate/restriction due to the smaller size, never even considered how the shape/size would affect the ability to actually "reach" the fuel. Thanks again!

Also, so I'm clear - were you referring to the sock that came with the pump as the generic sock, or did you mean the Precision sock I linked? I'll definitely replace the sock that came with the pump as I understand the benefit to a properly-sized sock now, but if there's something wrong with that Precision sock I'll find a different one.

 

You want the AC Delco or Delphi. Even then you want the one that's obviously twice as long. The short, single-sided pickup is the TBI/early V6 sock. Rock Auto had both the AC and Delphi versions not too long ago. AC Delco TS18, Delphi FS0029.

 

Got it, thanks again. Found the Delphi FS0029 for $17 shipped, so I'll go that route.