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Friday, June 3, 2016

Dirty Diesel

Here's a quick sum up of the way my diesel to waste veggie oil converted van operates. It starts on diesel. When the engine and the waste veggie oil both warm up, a flick of a switch draws fuel from the waste veggie tank. Before shutting the engine down for the night it has to run a few minutes on diesel to flush the veggie out of the engine.

Thanks to screens and honking big filters the veggie tank can process some pretty nasty fuel. Unfortunately, the diesel side is put together differently. The sending unit inside the diesel tank has some built in coarse filters. Unfortunately, when they get plugged options are limited.

To physically access those filters requires the removal of the 35 gallon diesel tank. It's the sort of job that one does not attempt lightly. Two years ago I had the sending unit replaced by my local mechanic. It was a nasty job and cost more than a few dollars.

Today I tried something different. Using a big compressor I blew air backwards through the fuel line to clear the filters. That works for a while, but since the crud is still in the tank those filters soon plug once more.

I've a small 3.5 gpm diesel fuel transfer pump. I was able to pump just about all of the fuel out of the tank. Then I added about 3 gallons of clean fuel. Once that was in I rocked the van to stir up any gunk that had settled to the bottom of the tank. After the tank was pumped dry once more I added about 4 gallons of clean diesel to the tank. That should get me back to town where I can refuel.

So what happened to the 25 gallons of dirty diesel? 15 gallons went into my heating oil tank. Diesel fuel and #2 heating oil is very similar. Oil tank filters are cheap and easy to change. 5 gallons went into my veggie tank. The veggie filter can easily handle the dirt particles. Another 5 gallons is sitting in a fuel jug. That diesel will also be used to cut waste veggie until it's all used up.

The van started fine and air purged itself of the system. I've yet to give it a good road test. Hopefully I've removed enough dirt from the tank. If not I can always repeat the whole process once more.

Where did the dirty diesel come from? I've no idea. When I'm around home I'm pretty careful where my diesel comes from. On the road there's no telling what you're going to get. It only takes one tank of bad fuel to cause endless problems. No doubt that bad fuel is the reason I've had to change the diesel filter mounted on the engine more often too.



  1. When I owned a gas station twice a year my tanks had 1 to2 hundred gallons of contaminated fuel suctioned from the bottom. Every one sets there cut offs different mine was never below 400 gallons to avoid causing what you just fixed. A semi annual tank suction cleaning of the van would help both tanks.

    1. I think I'll take your advice and pump out the tank on a regular basis.

  2. It's a shame there's no way to filter the fuel before it enters the tank.

    1. I'd be happy if there would be an easily replaced filter somewhere outside the tank.

  3. The diesel tank on my RV has a drain plug at the center low point where it can be drained when the tank gets low to clean out any settlement in the bottom. And as you guessed, I haven't ever drained it. . .