EFI with older gas tank (1 Viewer)

riggzola

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Woodstock GA
 
As I understand it, this is the pickup tube on my older (72) gas tank, which is around 1/4". I'm in the process of installing a Holley Sniper EFI which recommends 3/8" supply line. Can I run a 1/4" line to the pre-filter without issue or do I need to enlarge or install a new pickup in the tank? I'd be interested in what folks are doing for aftermarket pickup tubes also.

Another option would be an in tank fuel pump. I've started to look into that option as well. That would take care of the need for the return line in a single location also.

20200930_093219.jpg
 

DangerNoodle

I'm bored
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As I understand it, this is the pickup tube on my older (72) gas tank, which is around 1/4". I'm in the process of installing a Holley Sniper EFI which recommends 3/8" supply line. Can I run a 1/4" line to the pre-filter without issue or do I need to enlarge or install a new pickup in the tank? I'd be interested in what folks are doing for aftermarket pickup tubes also.

Another option would be an in tank fuel pump. I've started to look into that option as well. That would take care of the need for the return line in a single location also.

View attachment 2450916
A surge tank is also a good option if you don't mind putting something else in your engine bay. It would allow you to use your factory lines to the surge tank, and then the sniper pump from the surge tank to efi.
 
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For the sake of argument, the factory 1/4" setup worked to deliver enough fuel when sucked by a mechanical pump for a truck that (at full throttle) might get 8 mpg. The full-throttle fuel mileage wouldn't be any different with EFI, so in spite of Holley's recommendation, I think the 1/4" feed is just fine from a capacity standpoint.

An in-tank pump would be slick, of course, but more work. Since you don't have a factory return-line setup, in fact, it might make the most sense. There are some threads on this, and you want to cut carefully to avoid in-tank baffles and/or uneven top surfaces that will make sealing the in-tank pump setup difficult.
 

riggzola

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Woodstock GA
 
Many will run my rear fuel cell with in-tank pump as their one-and-only tank.
I've looked into this and in fact your tank in particular, but not ready to make that much alternation at this point. Maybe in the future once I realize I need more capacity.
 

riggzola

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Woodstock GA
 
For the sake of argument, the factory 1/4" setup worked to deliver enough fuel when sucked by a mechanical pump for a truck that (at full throttle) might get 8 mpg. The full-throttle fuel mileage wouldn't be any different with EFI, so in spite of Holley's recommendation, I think the 1/4" feed is just fine from a capacity standpoint.

An in-tank pump would be slick, of course, but more work. Since you don't have a factory return-line setup, in fact, it might make the most sense. There are some threads on this, and you want to cut carefully to avoid in-tank baffles and/or uneven top surfaces that will make sealing the in-tank pump setup difficult.
I was thinking the same thing. In my mind, it's not going to use any more fuel despite the fuel pressure at the EFI being higher. I can't get my mind around the physics, but your statement seems right.

I'll continue to research the in-tank option as well, especially since I haven't purchased my external pump yet. There's quite a bit of reading to do. Seems like there are certain advantages like you said. I appreciate the input.

btw ... just caught a glimpse of my avatar and it seems appropriate for this discussion :).
 

Steamer

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Miami, FL
 
 
Keep in mind, the external pump that Holley supplies moves a lot of fuel. Much more fuel gets returned to the tank than gets used by the Sniper.
I'm confident a Sniper setup returns way more fuel to the tank then does with a stock carb & mechanical pump. You may be fine but just saying, with a Sniper setup, more fuel will be coming out of that fitting than ever did before.
 

riggzola

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Woodstock GA
 
Keep in mind, the external pump that Holley supplies moves a lot of fuel. Much more fuel gets returned to the tank than gets used by the Sniper.
I'm confident a Sniper setup returns way more fuel to the tank then does with a stock carb & mechanical pump. You may be fine but just saying, with a Sniper setup, more fuel will be coming out of that fitting than ever did before.
That's something I haven't thought of. Good point because they recommend 5/16-3/8 return line too!
 

reddingcruiser

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You can do it!

If you use a late model FJ40 tank with the recess for the overflow tube you need to flatten it to allow just about ANY pump setup to seal. It's not difficult, just takes a bit of metal work. Or you can source an early tank without the recess.

The second picture pic is for a TBI pump.

The third is picture is the prototype for my LS swap. Top fitting shown was an early configuration for the filler overflow, but now I use a bulkhead fitting directly into the tank, about where the orange and purple wires are coiled up. The pump itself is from an '03 Tahoe. and uses the OEM GM lock ring to hold the pump in place.

The link below is the same type pump Man-A-Fre uses in their FJ40 rear tank, and it can be modified to fit the OEM 40 tank.


Mine was a lot less expensive and only took about couple hours on the lathe and drill press.

Be careful when using a 'used' tank. Though I've been welding a long time, understand purging procedures, inert atmospheres and working with tanks filled with water, but I still prefer to work on new tanks.

Dick's Pictures 153.JPG


TBI Fuel Pump 3.jpg
New Fuel Pump (2).jpg
 

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