T-H Marine Mercury Tank Connector 1/4in NPT

Fuel fittings are the kind of part nobody thinks about until one starts leaking. This T-H Marine tank connector is the male fitting that threads into the fuel pickup on Mercury outboard fuel systems, giving your fuel line a clean, leak-free place to lock on. It carries a 1/4 inch NPT male thread and replaces OEM part number 99105-00193, so if the connector on your portable tank or fuel system has seen better days, this is a direct swap.

Here's what usually happens. The old connector spends a few seasons soaking up ethanol-blended fuel and baking in the sun, and the plastic gets brittle. One day you go to prime the bulb and you smell gas, or you spot a wet ring around the fitting. That's your cue. A weeping fuel connection isn't just a nuisance out on the water, it's a safety issue you want handled before your next run. Replacing the connector is a lot cheaper than replacing a tank or chasing a fuel-air leak that makes the engine stumble.

Installation is straightforward if you've done any fuel work before. Back the old connector out of the tank fitting, clean the threads, and wrap the new 1/4 inch NPT male thread with a fuel-rated thread sealant. Don't use plumber's tape rated only for water, and go easy on the torque. You're sealing against fuel, not cranking a lug nut. Thread it in snug, hook your fuel line up to the connector, and prime the bulb. Watch the fitting for a minute. No drips, no smell, you're good to go. If you do see it weeping, back it out, add a little more sealant, and reseat. Fuel work rewards patience over muscle, and a connection that's dry on the trailer stays dry on the water.

A quick word on that NPT thread. NPT stands for National Pipe Taper, and the taper itself is what seals as you thread it in, so the fitting gets tighter the deeper it goes. That's why the sealant matters and why you don't need to gorilla it down. If you ever break the connection to winterize or pull the tank, the same connector threads right back in as long as the threads stay clean. Give them a wipe before you reseat and you'll get many seasons out of a fitting like this.

This is the tank-side connector, so it's the fitting that lives on the fuel supply, not the engine inlet. It's built for Mercury outboard fuel systems that used OEM 99105-00193, which covers a lot of portable-tank and remote-tank setups. If you're not sure which connector your rig uses, pull the old one and check the thread and the OEM number stamped on the fuel components before you order. Matching the fitting to your existing fuel line coupler is what keeps the whole connection tight.

What it isn't: it's not a full fuel line kit, and it doesn't come with a hose or a primer bulb. It's the connector itself, the piece that so often cracks and strands you at the ramp. If you're rebuilding a whole fuel line, plan on this connector plus your hose, clamps, and bulb. Buying the connector on its own is the right call when the rest of your line is still in good shape and you just need to kill a leak.

T-H Marine has been building rigging and fuel-system hardware for boaters for decades, and their fittings are made to live out on the water, salt, sun, and ethanol included. It's a small part with a big job. Keep a spare in the console if you run a portable tank, because a cheap fuel leak has a way of showing up on the one weekend you can't afford it.