Diesel showers

A diesel engine won't run when air gets in its fuel system. I have been contending with the air problem in Ms. Bettencourt's 30-year-old Kubota 3-cylinder diesel for at least a couple of years. Every time I think I have the problem fixed, the fix has proven only temporary.

Only one thing appears to be sure about the air intrusion: It has to be happening some place between the tank and the fuel injection pump. So this time, I disassembled the whole system -- from tank to injection pump.


The first fault I found was not air related, but was a lucky discovery nevertheless. This bracket, bolted to the aft end of the engine, serves as a pivoting point for the throttle and shift cables, and as a mounting surface for the on-engine fuel filter. The filter body bolts into the two large holes in the foreground in this photo. A replaceable spin-on filter canister screws into the bottom of the filter body.

Anyway, if you click on the above photo it will enlarge and you should be able to see the pre-catastrophic crack in the rusty metal. This was a the lucky find. I will get this fixed and will clean up and paint the part before re-installing.

The next discovery was on the filter body itself (left). The mating surface between the filter body and the gasket on the spin-on filer canister was heavily corroded. I wire-brushed the mating surface corrosion, then polished the surface with steel wool. Once re-assembled with a new canister, this part of the puzzle should be air-tight.

And, while I have it all apart ...

... all the fuel lines and hose clamps will be replaced and I will do something about this strange fixture on the top end of the fuel withdrawal tube (shown here laying across the coil of fuel line hose).






Here's a closer look at this funny fitting. The pipe coming out of the solid-looking elbow has a substantially smaller inside diameter than the rest of the fuel system plumbing. It could be a fuel-flow choke point. It could be making the the suction side of the lift pump have to work harder. Perhaps this too could be a part of the air intrusion problem.

My plan is to cut this little tube off and bore, tap and thread this thing so it will accept a 5/16-inch barb fitting such as the barb shown in the assembly at the bottom of the photo above.

After that's done, I'll put the whole system back together and bleed the air out of everything.

That's when the diesel showers will happen. I have never failed to avoid liberal sprayings of bubbly diesel fuel when I bleed air from Ms. Bettencourt's fuel system.

After the bleeding, and probably before I clean my glasses and launder my shirt, I expect the old girl's power plant to start up easily.

Only time will tell if this will solve the air problem. Stay tuned to find out please.