Holley 255 LPH OEM Style EFI Fuel Tank Modules 

Hey, Thanks for all the feed-back! Most of the early muscle cars had 5/16" hard lines on them so that is where we started. I know there were exceptions to the norm ( ie. hemis, and alot of high hp big blocks had 3/8" lines). I will definitely pass this great info to our engineering team! thx J

my factory sender has a return line

Yes, Sniper can be run without a return line. There are benefits to having a return line but it will be just fine if you use the 12-304 pump module! Thx J

Correct, the returns can be capped off on the Sniper when using this return-less pump. Thx J

@@HolleyPerformance So just a rubber cap is all that's needed? or is there a special threaded earl's fitting that I need to buy? I hooked up the return back to the tank. I'm guessing I should have ran that to the charcoal canister instead... The instructions were great for wiring but wasn't clear on the return vs vent...

No. You will just need a 100 micron filter down stream.

Not yet

Yes, you should always use a post filter! This pump is not designed to be used in a PWM setup. It is possible to run it that way (granted the driver is matched to the pumps frequency and current) but, the gear-backlash of a g-rotor pump will not handle the abuse for long. A turbine style pump is what is recommended for PWM set-ups. THX J

HolleyPerformance why does Holley advertise it at the end of the video for MSD atomic applications? I just purchased one. I use the car very rarely. Perhaps 1000 miles a year, should l return it?what do you recommend for a 69 Camaro running a returnless system.

The Atomic can be used with a standard fuel pump or a PWM style pump. You can make the selection on the handheld controller. J

HolleyPerformance the MSD settings only allow non pwm with a return line. Will the system run that way, have you tested it?

Here are the instructions from page 3 of the instructions. We have found that a return-less style fuel system is not the most effective way to deliver fuel to the TBI but it will work and has been tested. Hope this helps. J FUEL SYSTEM REQUIREMENTS The following details pertain to the fuel system requirements. Installation steps specific to the fuel system are covered in the Fuel Pump Kits supplied separately from the Atomic TBI, PN 2910, Kit. The Atomic TBI requires a high pressure fuel pump system. Depending on your engine combination, the Atomic TBI requires a minimum of 42-48 psi to operate and it can be used with a return or returnless fuel system. When selecting a pump, regulator and lines, be sure each component is designed to perform at high pressure. MSD offers a fuel pump, hose and accessories to complete your installation. Following are some guidelines in helping set up a fuel system for your Atomic as well as components available separately from MSD. • The Atomic is capable of operating with a return or returnless style system. For best results, MSD strongly recommends an in-tank pump. Installing the fuel pump in the tank results in quieter operation, less chance of cavitation and a reduction in pump temperature. • When running a returnless fuel system (Pulse Width Modulated), it is strongly recommended to install the pump in the tank. It is recommended to use an MSD Atomic Fuel Pump, PN 2925 or PN 2926. • If mounting the pump in the tank is not an option, install the pump as close as possible to the tank. Within 2-feet of sending unit is recommended. • Do NOT use hard line when plumbing the fuel system. When using a PWM fuel system, cavitation could cause unstable fuel pressure resulting in poor engine performance. • When used, an adjustable regulator must be installed on the return side of the throttle body.

Yes you can! provided we offer one for your vehicle.

@@ragingkajun86 how it's work for you with returnless system

What about it?? An in-tank pump is far less likely to heat soak than an external pump since the fuel around it acts as a heat-sink to dissipate any heat built up by the pump. thx J

Exactly, how is that little line going to handle 50psi?