Fuel Gas Tank with Lawnmower Gas Cap Engine Fuel Tank, Plastic Gas Tank Compatible with B&S, Replace# 594112, 84004115

What It Is

This is a plastic replacement fuel tank assembly for walk-behind lawn mowers, designed to hold gasoline and supply it to the engine via the attached fuel cap. It’s a direct-fit replacement for Briggs & Stratton engines using OEM part numbers 594112 and 84004115.

Fitment & Compatibility

Before buying, confirm your mower’s engine model and series—this tank fits most B&S single-cylinder engines (e.g., 450, 500, 550, 625, 675, 725 series) but not all. Measure your existing tank’s mounting hole spacing (center-to-center) and overall dimensions; this tank is roughly 8.5” long x 5.5” wide x 4.5” tall. Check that the fuel outlet nipple diameter matches your fuel line (typically 1/4” or 5/16”). Also verify the fuel cap vent type (some B&S tanks use a non-vented cap; this one includes a vented cap—ensure that’s compatible with your engine’s emissions system).

Key Things to Know

• Quality: Plastic is durable but may feel thinner than OEM—handle carefully during installation to avoid cracking the mounting tabs.
• Installation difficulty: Easy (20-30 minutes) for DIYers—remove old tank, transfer any fuel line clamps or shut-off valve, and bolt in place. No special tools required.
• Common gotcha: The included gas cap may not seal perfectly on all mowers; test for leaks before filling fully. Some users report the cap vent can cause fuel spillage on slopes—consider swapping for your original cap if it fits.
• Fuel line compatibility: The tank’s outlet is barbed; you may need a new fuel line if your old one is brittle or the diameter differs.

Should You Buy It

This is a solid budget option if your B&S mower’s OEM tank is cracked or leaking and you want a quick, no-mod replacement. It’s not ideal if you need a heavy-duty tank for commercial use or if your mower uses a non-standard mounting pattern—measure twice before ordering. For the price, it’s a reliable fix for most homeowner-grade mowers.