The FASS RM-1004-A is an aluminum fuel filler neck return manifold designed for high-flow diesel fuel air separation systems. It splices directly into a 1-1/2 inch rubber fuel tank filler neck hose, providing a dedicated port to return air, vapor, and excess fuel back into the tank. FASS machines the body from durable aluminum and outfits it with an integrated return barb to accept fuel return line hose.

Foaming fuel, tank aeration, or avoiding the need to drop the fuel tank and drill extra bulkhead return fittings are what this manifold is for. By routing the air and vapor return line straight down the filler neck pipe, installation time is cut down significantly while ensuring clean fuel separation back to the fuel supply. It is the inline filler neck return manifold only; fuel return hose and hose clamps are sold separately.

It fits diesel trucks and custom fuel setups equipped with a 1-1/2 inch inside diameter fuel filler neck hose, commonly used with FASS Titanium, Titanium Signature, and Industrial Series lift pump kits.

Fitment

• Universal fitment for Ford Powerstroke, Dodge Ram Cummins, and GM Duramax with 1-1/2 inch filler necks
• Compatible with FASS Titanium, Titanium Signature, and Industrial series return lines
• 1-1/2 inch outside diameter main tube body
• Integrated fuel return barb fitting
• High-grade aluminum construction
• Manifold unit only

Measure the outer diameter of your existing filler neck rubber hose before cutting to confirm 1-1/2 inch inside diameter sizing. Use a clean, straight cut across the rubber neck and de-burr any edges before sliding the manifold into place. Install heavy-duty gear clamps or T-bolt clamps on both sides of the manifold body to ensure a vapor-tight seal that prevents fuel odors or leaks during refueling.