Dear Charles,

Hope you're well. The anti-slosh baffle likely was factory-affixed using heat to fuse the plastic baffle to the tank bottom. Given the fire/explosion risks inherent to using any heat-generating device inside a gas tank, I'd not try to re-install the baffle using any heat-based process.

I suspect that if the baffle is left loose, it will eventually damage the fuel send unit's barrel. If the baffle is cut into pieces and removed, the fuel gauge reading might vary more than it does with the baffle in place, i.e., after turns or sudden stops.

Having changed in-tank fuel pumps, I realize that access to the fuel tank's opening is limited, especially in a sedan.

The best way to re-affix the baffle is to use a sealant rated for fuel tanks, e.g. Pro Seal (see https://www.aircraftspruce.com/pages/cs/fueltanksealants/ps890.php )

Both surfaces (the baffle's underside and gas tank floor) must be cleaned to remove any gasoline residues. Gasoline is a mix of various chemicals, some of which are wax-like. If those residues remain on the plastic, they will defeat almost all glues, adhesives, and caulks.

Thus, you must remove fuel from the tank. Once the tank floor is dry, wipe it with a clean, white rag wet with Methyl Ethyl Ketone (MEK) a highly flammable solvent. MEK will remove every trace of oil, grease, wax, etc. For each pass, use a fresh, clean, white rag. When the rag no longer is discolored, you've removed all residues. Do the same to the baffle's underside.

Be sure to have plenty of ventilation, while using MEK. Do NOT do this job in a closed garage!!! Wear a respirator, which has filter elements that remove fumes. Do NOT rely on a dust-mask. Those are totally useless, when it comes to trapping chemical fumes.

Apply ProSeal according to the directions. For guidance, see: http://www.vansairforce.net/articles/tank_sealant.pdf . Position the baffle so that it will still allow the fuel send unit's barrel to seat (pointing downwards and parallel with the fuel tank's rear wall). Press the baffle against the tank floor and allow the Pro Seal to cure.

Hope this helps.

Yours faithfully,

Spook