2015 25.1 Ask Albert

Ask Albert!

Clearing a Fuel Tank

Dear Albert, I have a two-cylinder Vanmar row tractor. The tank got gas in the diesel and the tractor quit running. What do I do to get things right again? ~ Tractor Quit

Dear Quit, Hopefully the tractor just started running slower and stalled out, because sometimes the gas in the diesel will ‘run away’ and increase in speed until it blows up. You could also do damage to the injector pump because that gas doesn’t have lubrication for injector pump pistons.

So here’s what you want to do

First, drain the fuel out of the tank. Remove filters (fuel line, prefilter before the tank, and injector pump). If there’s a drain on the injector pump, drain it. Open the vent on the injector pump to release the vacuum so the pump will drain.

Remove all injector lines (one per cylinder) and drain the gas out of the lines. Allow to drain out for a couple of hours.

Reassembly Put the drain plug back in the injector pump. Replace the fuel filter. If the filter is not dirty, you can air it out and reuse it (make sure it’s not torn and that it’s clean enough to be serviceable). Reattach fuel lines from the tank through the fuel filter line to the pump.

Fill the fuel tank with clean diesel fuel. Allow time for the diesel to go through the filter, pump, and come out the injector pump vent (which you opened earlier) until a clear stream of diesel with no bubbles is observed. Close the vent.

On this particular tractor, there’s a compression release. Engage the compression release and roll the motor over with the starter. Compression release makes it easier on the starter and allows the motor to turn over more freely.

Turn over until you get distinct, visible squirts of fuel out of the injector fittings on the pump (where the fuel lines connect to). Once you get fuel coming through the injector fittings, reattach the injector lines to pump. Repeat turning the motor over until fuel comes out the other end of the injector line. Once fuel gets to the injector line, you can reattach the line to injector. Start turning the motor over and disengage compression release so the engine will catch.

This last step may need to be done several times until the motor starts. You should now be back in business. The motor should come to a smooth idle and operate normally.


When fueling up equipment, take time to smell the fuel to determine if it is gas or diesel. Smell it either in the tank or in the can. You can observe the quality of fuel at the same time to make sure it’s not old.

Diesels can be quite sensitive to gas introduced into fuel systems, especially the newer modern equipment with electronic injectors. If you put diesel into a gas motor, it’s more forgiving—especially older carbureted engines.

As gas engines become more complex and computerized, they become less forgiving. As a result, mixing fuels causes more damage.

At a garage, it’d probably cost some $500 to have the above described procedure done. Or you can learn how to do it yourself.

Or you can avoid mixing fuels.


Albert Roberts was raised on a fourth-generation grain and cattle operation in North Dakota. Albert has ranched in the Okanogan for twenty-eight years with his partner Carey Hunter. [email protected] Albert Roberts, Pine Stump Farms, Omak  

Tags: advice, Engine, Fuel, Maintenance, Mechanics, Tractor

pdf2015_25_1_Winter Ask Albert.pdf