Tecumseh TVS90 Carburetor Removal

This old brute of a lawnmower spent the winter outside with fuel left in it. It starts, but there may God-knows-what-all sort of muck in the carburetor. So, in the interest of a trouble-free mowing season, I'll take the carb off and dismantle and clean it. I'll also remove the fuel tank, and exchange it for one I have that's clean and dry inside

I've posted about TVS90 carburetor maintenance before, but I didn't write up the removal procedure, so here goes.

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Tools needed are nutdrivers and combination wrenches in sizes 1/4", 5/16", 3/8" and 7/16".

The pictured lawnmower has an operator's engine speed control lever. That complicates carburetor removal a bit because of a governor/throttle-linkage plate that must come off.

Fuel Tank

The fuel line tubing is 5/16" I.D., secured with a spring-type hose clamp. Lever the tubing off of the fuel tank's discharge nipple.

Hold a fingertip over the open end of the nipple while you lift the tank up off its keepers at the rear of the engine cowl. It's helpful to have a salvaged automotive engine vacuum port cap on hand, so you can safely set aside the fuel tank.

And here's a view of the rear of the engine cowl with the fuel tank removed.

Note the channels that are the fuel tank's keepers.

Throttle Cable

Note the position of the cable jacket at its clamp. Loosen off the clamp and unhook the cable end from its lever.

Air Cleaner

Pry up the air cleaner's lid and remove it.

Two screws fasten the air cleaner's body to the carburetor's intake flange -- remove those and the air cleaner is free to come away.

One of the two screws is rather concealed at the inboard side of the air cleaner's output horn. With the air cleaner removed, note the nipple that connects to the crankcase ventilation tube. At reinstallation, take care to remake that connection as you get the air cleaner in place.

Here's a view of the air cleaner's output horn. Note the square cross-section o-ring seal that resides in a circular notch.

With the air cleaner off, you can see the governor/throttle-linkage plate that resides over top of the carburetor.

You have to remove the engine's cowl before you can get that plate off. Cowl removal is straightforward; there are two screws at the front of it and two screws at the rear of it. There's a fifth screw that fastens the oil filler tube to the cowl. The oil filler tube may tend to tumble once it's unfastened. Set it aside and take care not to let foreign matter get into the tube's hole to the sump while the tube is off.

With the cowl removed, you have clear access to the governor/throttle-linkage plate.

Note the following:

• The mower's engine speed lever does not operate the throttle directly. The lever acts on the governor spring, so as to alter governed engine speed.
• There's a single kill wire to be disconnected at the front of the plate.
• The throttle link attaches to the uppermost hole in the governor arm.
• The governor spring attaches to the next hole down in the governor arm. The spring's link attaches to the plate's engine speed lever.
• The plate is attached to the top of the intake pipe by two screws in elongated holes. Evidently, the position of the plate is adjustable -- I have no idea why. Note the plate's position and be sure to get it back the same way at re-installation.

With the governor/throttle-linkage plate removed, you're ready to remove the carburetor from the intake pipe.

The fasteners are two 1/4"-28 screws with nuts. The inboard screw and its nut are a bit awkward to deal with. When you get the carburetor off, note the gasket that goes between the carburetor and the intake pipe. As long as that gasket is undamaged, it's reuseable. Replace it if in doubt about its condition -- that gasket is important.

And there we are, at the point where the carburetor can be opened up and its innards attended to.

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