Am I missing something? can't I use sending unit with return - Team Camaro Tech
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post #1 of 6 (permalink) Old Sep 20th, 14, 11:05 PM Thread Starter
James
 
Join Date: Jun 2013
Location: Utah
Posts: 23
Am I missing something? can't I use sending unit with return

I'll be installing an LS1 5.7 from a 98 Camaro into my 68. My plan for setting things up for fuel injection was to buy a new sending unit with a return built in, like this one:

http://pages.ebay.com/motors/link/?n...881106&alt=web

It's made for a stock tank, 3/8 supply and 1/4 return line

Why can't I just use an external electric pump, plumb everything and be done? It seems like everyone is buying special "fuel injection" fuel tanks.

What am I missing here?
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post #2 of 6 (permalink) Old Sep 21st, 14, 04:42 AM
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Steiner
 
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Location: Lyman, SC
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Re: Am I missing something? can't I use sending unit with return

You can run external. I do. There are some benefits to internal though....typically quieter operation and EFI tanks have baffling inside to prevent fuel starvation during cornering/acceleration when fuel level gets low. Pump should run cooler too. Also pump mounting with external is tricky because you have to get it as low as possible, the pumps are pushers not pullers.

Usually it's recommended to run at least the same size return as supply. A smaller line can cause restriction that's essentially read as pressure so there can be issues with the regulator.

Mine is a stock tank and single line sending unit with the return plumbed in through a bulkhead fittings. Haven't had any issues other than changing to a quieter pump. Tanks Inc has a pretty good looking internal setup for around $500 tank/pump/sending unit and I imagine I'm going to get one sooner or later.



Semi-ghetto.....


'69 Camaro
Dart 400-AFR 195-224/224 HR-Powerjection III TB with F.A.S.T. Sportsman XFI
TKO 600-Moser 3.42-Detroit Truetrac
500hp/538lbft

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'69 Camaro Beater-SFT 327-M20-Moser 4.10-sold
'02 Z/28 vert-stock-sold and totaled
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post #3 of 6 (permalink) Old Sep 21st, 14, 06:37 PM Thread Starter
James
 
Join Date: Jun 2013
Location: Utah
Posts: 23
Re: Am I missing something? can't I use sending unit with return

I figured there was baffling in the tanks built for fuel injection, but my car is going to be a daily driver so I don't think I'll have any issues with starvation. I was given a free tank today so now I just have to figure out how I need to modify it for the return. I'm thinking of using the original sending unit and drilling a hole in it for the return. I understand original sending units work better with Autometer gauges, since newer sending units are different ohm readings or something like that.
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post #4 of 6 (permalink) Old Sep 22nd, 14, 04:50 AM
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Steiner
 
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Re: Am I missing something? can't I use sending unit with return

If you're not going to worry with baffling then you might as well try the Spectra pump and sending unit they make for their EFI tank. I believe that the EFI tank is the same as their stock tank other than having some baffling or a tray inside so the EFI pump will go in a stock tank. Just would need relay, wiring, regulator, and plumbing. I have a stock style Spectra tank and sending unit.
http://www.amazon.com/Spectra-Premium-SP177A1H-Fuel-Assembly/dp/B00BJXUIQI#productDetails

'69 Camaro
Dart 400-AFR 195-224/224 HR-Powerjection III TB with F.A.S.T. Sportsman XFI
TKO 600-Moser 3.42-Detroit Truetrac
500hp/538lbft

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'69 Camaro Beater-SFT 327-M20-Moser 4.10-sold
'02 Z/28 vert-stock-sold and totaled
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post #5 of 6 (permalink) Old Sep 22nd, 14, 07:07 PM Thread Starter
James
 
Join Date: Jun 2013
Location: Utah
Posts: 23
Re: Am I missing something? can't I use sending unit with return

That's a great idea, I didn't know somebody made an in tank pump/sender assembly. It says it fits spectra tanks, what about my factory tank?
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post #6 of 6 (permalink) Old Sep 23rd, 14, 04:35 AM
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Steiner
 
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Location: Lyman, SC
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Re: Am I missing something? can't I use sending unit with return

Good point. In looking at it, I think the opening on the EFI tank might have to be larger than on their stock tank. It probably won't fit. I pulled up their stock sending unit and the EFI one and it does look like the locking ring is different although it's hard to compare the size of the two.

You might be able to braze a return tube onto the stock unit. I tried just JB Welding one in...didn't work out too good so I went with the bulkhead fitting. Also don't forget you're going to have to vent the tank. Moroso makes a fitting that they call a fuel return that goes in between the tank and filler but it can be used for a vent connection also. I have a tube JB-Welded into the neck and go from there into a charcoal canister in the trunk, then vented back out behind the license plate but I have a '69.

Here's a thread that may help. The Moroso part is discussed as well as what someone else did with a stock sending unit for return.
https://www.camaros.net/forums/showthread.php?t=206921
https://www.camaros.net/forums/showpost.php?p=1788482

'69 Camaro
Dart 400-AFR 195-224/224 HR-Powerjection III TB with F.A.S.T. Sportsman XFI
TKO 600-Moser 3.42-Detroit Truetrac
500hp/538lbft

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'69 Camaro Beater-SFT 327-M20-Moser 4.10-sold
'02 Z/28 vert-stock-sold and totaled
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