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Discussion Starter · #1 ·
I don't have the Holley Sniper EFI yet, but have a question about the fuel pump I'll need. What happens if you don't have a return line to the fuel tank?
 

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Well the Sniper uses a return style system so you'll need to run one. When I did my Sniper install I ran a 6an feed line and used the stock hard line as a return. I run a 255lph pump in tank as well.
I've heard tell of people converting the Sniper to returnless setup but that seems like a good way to boil fuel with the pump dead-heading like that.
 

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One way or the other you will need a return.
 

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Discussion Starter · #4 ·
Thank you for the information. Come of the Holley advertisement talk about buying it to use either way. I just want other users experience. My friends are in the process of finding me one for the best price.
 

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Discussion Starter · #5 ·
I have a 350 with a Comp Magnum cam in it. I'm not trying to figure out what kind of milage I will get, but interested to see what kind of milage you get with it on your El Camino?
 

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Well being that I've had one on my 350 for a good while, I can say that when it works well, the engine runs awesome. These units are incredibly susceptible to electrical noise interference though. In fact I'm typing this while on hold with Holley technical support about an issue I just can't seem to shake causing an erratic idle. Holley is basically the best on the market for affordable EFI solutions but that doesn't necessarily mean it's a bulletproof system.
With that also being said, the fact that the car instantly starts every time and gets about 16ish mpg overall makes the hassle worth it.
 

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Discussion Starter · #7 ·
Thank you for your information. I understand that issues may assistance from Holley. They have helped me on my Street Avenger carburetor and even offered to rebuild it as part of the warranty. I've had it since 2004.
 

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1987 GMC Caballero, 350, Holley Sniper EFI, 200-4R
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Buy a roll of 3/8" aluminum tubing and run it along side your existing fuel line. Put your pump in the tank
 

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1966 El Camino
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Here is the write up of the sniper install on my el camino.

How to Install Holley Sniper TBI Fuel Injection on a Chevy Big-Block (motortrend.com)

We ran new line for the supply and reused the original rigid line for the return. Holley advertises that you can run it either way but I've heard that the return style is far better. to give you some idea of the efficiency, I got a max of 18 mpg once in this car and thats with a 500+hp big block, that represents about a 28% improvement over the best of 13mpg when carburated. However in truth i usually am getting 15 + mpg with the car, I've yet to duplicate that awesome 18 .
 

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1987 GMC Caballero, 350, Holley Sniper EFI, 200-4R
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78 Elk you will have to take out the fuel tank.
On my Caballero I purchased an in tank pump & gauge sending unit for an 86 V6 EFI el camino. Holley tech line told me the stock pump would not provide adequately for the Sniper but recommended one of their direct replacement pumps. The Holley pump was the same physical size and not difficult to change from the stock pump to the Holley. I was able drop the unit into the tank for a sanitary and quiet operation.
However, Holley recommends at least 3/8 supply & return lines. The V6 unit has a 3/8 supply, but a 5/16 return and vent flared tubing fittings. I drilled a hole in the top of my tank and installed a 3/8 90° bulkhead fitting for my return line. I ran the 3/8 aluminum tubing parallel to the factory supply line along the passenger side of the frame, all the way forward through the same hole. I highly recommend buying good quality hose clamps for fuel injection (Summit Racing or Jegs).
With the excess aluminum tubing I fabricated lines in & out of the throttle body, along the right valve cover and down, similar to the factory line for the carburetor. A short length of neoprene hose connects to the lines from/ to the fuel tank.
I'm very happy with the Sniper. I'm fortunate, never any software or electronic issues. Once installed it's like modern EFI vehicles; no pumping to set the choke or warm up before putting in gear. Turn the key to run, the electric fuel pump kicks on, turn the key to start and it does. Then I put it in gear and go.
 

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I was also under the impression you "could" deadhead some of the snipers with the Holley in tank fuel pump

I haven't installed a sniper myself, nor have I owned a 5th gen
Does the Gbody fuel sender interchange so you could use this piece from Holley?
Holley Sniper EFI 12-306 Holley EFI Fuel Tank Modules - 255 LPH - GM G-Body

you can also plumb the return back to filler neck instead of the tank
I have done this in the past on several vehicles and it makes quick work of a return line
Moroso 65385 Moroso EFI Fuel Return Line Kits | Summit Racing

When I was debating a Sniper I figured I would use the corvette filter/regulator to keep the return short
I found photos form this article helpful Installing Holley’s Sniper EFI Quadrajet System on a 1970 Corvette (motortrend.com)

Good luck 78 Elk, I know you will keep us posted.
 
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Discussion Starter · #17 ·
Thank you for your information. I'll have to check some out after it gets here. My friends race a Camaro and they know their stuff and own a NAPA store.
 

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I'm satisfied with my Sniper and return line. Why spend the money for a Sniper and not provide it with the optimum environment? Wiring it directly to the battery and having the appropriate fuel lines is the best way to have a problem free installation.
 

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I have a Holley returnless sender on my Sniper set up. It works fine. All you have to do is drop the tank and swap out the sender. I would probably run new fuel lines to the hard lines while your under there.
 

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Thank you. Then I'll have to take the tank off, is that correct?
you need to check the tank either way. rust holes. Return line keeps fuel cool and doesn't run the risk of damaging your pressure regulator. Pump runs cooler emerged in fuel and if you set the pickup low in the tank you will not loose the ability to utilise all the fuel in the tank, and you will not starve you EFI when you make turns.
 
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