Questions about running an external fuel pump....

[trapin]

I know that this is not popular but I saw a guy down in Pigeon Forge that was running one on his LS1 and I didn't think it was too loud.

Understanding that I must run a return from the regulator back to the stock tank, do I have to modify my tank to recieve the return line? I don't remember seeing a 2nd outlet to do this? If so...how is this accomplished?

[pist0lpete]

I am not sure what most people do with the return line on their inline pumps. I know its pretty much required that you at the very least add a sump to your tank. The major drawbacks to inline pumps are noise and shorter pump life because they do not have the cooling benefit of being submerged in gasoline. If you can live with those factors and make sure the sump is always wet then its really not such a bad deal.

[CarlC]

If you are running the stock tank and pickup then adding a return is easy. Just braze in a return line that mimics the OE pickup.

The harder part with a stock tank is baffling. You could add something like the Tanks Inc. part but it may not work well for spirited driving when the fuel level is low.

Craig Boone ran his car for years with no baffling but he could not track drive it reliably when the fuel level got low. It just meant he visited the pump twice during the day.

It may take some creativity but it may be possible to add a 255lph Walbro to the stock pickup and get it into the tank. I have a spare pump if you want to try and mock it up.

[trapin]

Thanks Carl...I'll keep it in mind.

I actually just got done talking to the guy that authored the LS1-into-first gen-swap thread over at LS1Tech and he said to use a big block sending unit (which has a return already on it). I think that's the easiest and cheapest route to take. As far as baffling, I'm not worried about that as this is not a track car. Too be safe I'll just never let the tank get more than half empty.

[Midnight68]

As for adding a 255lph Walbro to the stock pickup, it is possible and fairly easy. Thats what I did with my tank, while it isnt running yet it seems like it will work great. It puts the pump in the tank to keep it cool and easy to change if I ever need to.

[CarlC]

If you have a piece of tubing bent correctly, a drill, and a brazing setup you can add the pickup to the original. It's super easy.

[trapin]

I think I may have to do that Carl, because the 2-line sender that he was talking about is only for the '69 tank. I don't think it will work on the '68. Damn...looks like I'm fabbing after all.

[CarlC]

What's the differance between the two mounting points? I believe that they are the same. The primary differance between a '68 and '69 tank is the filler neck.

[trapin]

I think the opening up at the top that the sender plugs into is a different sized hole. I don't know for sure though. I'm asking that question over at Team Camaro right now.

[BonzoHansen]

Tony, I looked up the part numbers at rockauto. I used a 327 model for all years as that is pretty common:

1967 327:
Tank: GM32A
Senders:
SPECTRA PREMIUM Part # FG104A
Includes Fuel Sender, Float and Strainer (Fuel Pump Not Included); 5/16" Outlet

$80.79 $0.00 $80.79
SPECTRA PREMIUM Part # FG104B
Includes Fuel Sender, Float and Strainer (Fuel Pump Not Included); 3/8" Outlet

1968 327:
Tank: GM32A
Senders:
SPECTRA PREMIUM Part # FG104C
Includes Fuel Sender, Float and Strainer (Fuel Pump Not Included); 1 Outlet (3/8")

1969 327:
Tank: GM32B
Senders:
SPECTRA PREMIUM Part # FG104C
Includes Fuel Sender, Float and Strainer (Fuel Pump Not Included); 1 Outlet (3/8")

$82.79 $0.00 $82.79
SPECTRA PREMIUM Part # FG104D
Includes Fuel Sender, Float and Strainer (Fuel Pump Not Included); 2 Outlet

Tanks appears to be the same 67-68. Senders change like the tides, but appear to fit all years (note FG104C fits 68 and 69). No listing for filler necks. Pics of tanks online show no filler necks. Tanks are cheap too, less then $100.

[BonzoHansen]

In fact, engine size does not apper to matter (except the no listing on the 2 69 cars).

1967 Tanks
230: GM32A
250: GM32A
302: GM32A
327: GM32A
350: GM32A
396: GM32A

1968 Tanks
230: GM32A
250: GM32A
302: GM32A
327: GM32A
350: GM32A
396: GM32A

1969
230: GM32B
250: GM32B
302: NOT LISTED
307: GM32B
327: GM32B
350: GM32B
396: GM32B
427: NOT LISTED

Note: Again, all this queued from www.rockauto.com, so it is as good as there info.

[6'9"Witha69]

There are 3 types of pickups I am aware of (for all 3 years).
3/8 out only

5/16" out 1/4" return

3/8" out 1/4" return

[backtobasics]

You could use the existing "feed line" as the return. There is also the option of a bulk head fitting from Aeroquip, Russell, Earls, that could work. Drill a hole in top or side of tank, close to sender, and bolt in the bulkhead fitting. Try to keep it as far away as possible from the point where the fuel is being drawn from the tank, to minimize the possible cavitation caused by the returning fuel.

[trapin]

Bonzo, thanks for the information. My research is telling me that the return has to be 3/8 (same as outlet). So even if the 2-line sender from the '69 fit, it would not be sufficient for the amount of pressure on the return.

The bulkhead fitting is not a bad idea. Do they make an angled one? I looked online and only saw a straight one they made. With that one I'd have to have it stick straight out the back as opposed to being on top of the tank? That could cause problems under braking by having fuel rush back in to the return line when it's trying to drain under deceleration. Or maybe I'm overthinking it.

[backtobasics]

The bulkhead fitting is not a bad idea. Do they make an angled one? I looked online and only saw a straight one they made. With that one I'd have to have it stick straight out the back as opposed to being on top of the tank? That could cause problems under braking by having fuel rush back in to the return line when it's trying to drain under deceleration. Or maybe I'm overthinking it.

Overthinking. The pressure from the fuel coming back would overcome the pressure of fuel in tank, no problem. If angle is concern, mount a straight bulkhead, and run a 90 degree adapter, or hose end. It could be mounted in front, towards top and corner, for easy entrace?