Placement of fuel pump / Atomic recommends flexible 3/8” fuel supply line [not hard

[cdaum]

Anyone have a recommendation on where to locate the external fuel pump that came with the MSD Atomic EFI kit? Says to mount near the tank, but even with or below the bottom. Instructions also recommend NOT using hard line for fuel supply on this returnless system. Thoughts?

[Mark Eaton]

I'm using a Holley Sniper EFI kit which came with an in-line fuel pump and 3/8" Vapor Guard fuel hose. Not sure if I'm not supposed to use hard line. It clearly says to locate the pump as close the the fuel tank and as low as the lowest part of the fuel tank. Here is what I'm doing.

https://thefactoryfiveforum.com/attachment.php?attachmentid=79590&d=1516590371

[Papa]

My FAST XFI Street system came with an external pump and after a lot of advice from several forum members I ended up going to an internal pump. I bought a complete system from Gordon Levy. After receiving the system, I ended up doing braided lines, but used everything else Gordon sent me. The internal pump has a couple of key benefits. First, it runs cooler being immersed, and second the pump pulls from the bottom of the tank ensuring it always has fuel and doesn't rely on siphoning, which can be lost and cause fuel starvation. Gordon's pump fit perfectly in the tank without any modifications.

https://farm5.staticflickr.com/4504/37520372532_1e4d47d9b7_b.jpg (https://flic.kr/p/ZaxHyG)

[Frank Messina]

Instructions also recommend NOT using hard line for fuel supply on this returnless system. Thoughts?

Not sure in what context this recommendation is presented, but the standard guidance for fuel line plumbing is to use hard line for the long run(s) and flexible line for the short end runs that are subject to flexing and vibration. HTH

Frank

[edwardb]

I remember reading about this when the Atomic EFI system was released and I considered it for a build at that time. Ended up going old school carb, but that's another discussion. The Atomic EFI system supports either a standard return fuel system (separate supply and return lines) or a returnless system. For the returnless setup, the system pulses the fuel pump to maintain/not exceed the proper fuel pressure. They call it PWM (Pulse Width Modulated). With this setup, MSD recommends not to use hard lines because the PWM pulses will cause hammering in hard line.

The instructions are pretty specific about where to mount the fuel pump: "The Atomic’s fuel pump should always be mounted as close to the fuel tank as possible. Using a return style system this is less vital, but a closer mount will aid in keeping the pump cool. Using a returnless style fuel system it is vital that the pump be as close as possible. With this system the pump MUST be within four feet of the tank – preferably two feet or less. The pump should always be at or below the bottom of the tank. The pump should be plumbed with the supplied 3/8” ID fuel line from the tank."

More here: https://www.msdperformance.com/support/faq/

[GFX2043mtu]

I’m not trying to put a advertising plug out but point blank call Glenn’s performance and do what he says. He has more expierence with Ford Mustang fuel systems then any one as that is all he does. And he’s going to be honest and tell you what you need to make it safe and reliable regardless if you buy any thing from him. Also if you go soft lines you need PTFE lines because of the ethanol in fuels now all others will break down and seep gas in a couple years. If you go that route you also need them to be carbon lines so that you don’t build up a static charge in the lines and cause a major hazard.

[Itchief]

I used the atomic efi with an in tank pump and steel supply and return lines, a pressure regulator and a gauge mounted on the fire wall. I’m not saying that it’s better or worse than the external pump just my choice

I made the mistake of using the ported vacuum port for the distributor vacuum advance when I first installed the efi

Once you get it on the road if it wants to stumble as you accelerate increases the pump squirt value

Good luck

Rick

[cdaum]

Thanks. Looking at the in tank pump option.

[cdaum]

Thanks. An in tank pump might work best. Will avoid figuring out where to mount the external, particularly if I keep the returnless set-up.