Cold weather & fuel gelling—finding answers to fuel problems

Cold weather & fuel gelling—finding answers to fuel problems

In the past months, we have seen below normal temperatures that we have not seen in many years. These frigid temperatures have sent many fleet managers into a frenzy—fuel gelling problems are the cause.

Here’s what’s going on. The temperature is cold outside, below zero; say -2 or -3 degrees below. The truck will not run, it doesn’t even start, so mangers may blame any thing. Here is how some may approach the problem. Picture a dartboard. In the center of the board there is a little circle that represents the proper fuel, maintenance and experience. There are a few outer rings; the first outer ring closest to the center represents the driver; the next ring is maintenance; next ring is temperature, then the outer ring, grand daddy of all, is fuel gelling. In other words, the central point—fuel, maintenance and experience are the most important and hardest to hit. This represents the solution to the problem—and it’s where you want your “dart” (efforts) to land to win the game.

I have asked many fleet people if they have seen gelling, and they all said yes. I asked when? The answer was always “well THEY said so.” Okay, who is “Mr. They?” or, the “VP of Mystery?”

True story: I got a call from a client’s veteran employee who told me that all the fuel was gelling and the pumps would not work. I ask the normal questions and all the responses were foggy—or better yet—referred to the fact that it was zero degrees and everything was frozen. I told him that it was not cold enough to gel the fuel, but he said, yes it was. He reported that they had to change filters on the pumps. I said good. He told me he wanted to increase the micron or get blank filters. He added that he climbed on top the 12,000-gal. above ground tanks and he looked inside the tanks and all the fuel was gelled. Oh boy! Now I was totally confused. At this fleet, we had been blending fuel with 30% KERO for a week and it was not cold enough to gel. So for a slight moment I let my guard down and thought that maybe the fuel supplier delivered straight fuel, but the temperature was still not cold enough to gel the fuel. The fleet keeps jugs of fuel outside for visual and temperature checks.

This seemed like a dilemma. What does one do? I asked a member of the client’s team to ride for an hour and asked him to look to see if the fuel had actually gelled. I began to wonder if they may have needed an emergency load of kerosene brought in—then I thought about the fact that there may be no room in the tank if it’s “all gelled.” I worried I would have to look for plan B, C or D.

We did a little more sleuthing and discovered that the snowplow guy hit the electrical box and shut down the pumps. Now how do you determine gelling from and electrical box destruction?

The point here is, please remember that fuel gelling is often used as and excuse for what is wrong with fuel in cold weather, deep cold. But, it has to be below -15 degrees before fuel even begins to gel. It is normally ice crystals build up in the fuel line 90º nipples or on the filter water absorbent paper. The next stage is waxy build up on the filters—yes looks like wax—when you see the filter you can tell wax, ice crystals will melt by the time someone inside looks at it. It is not gelling as most fleets misdiagnose the problem.

Are you gellin’?

Here’s what you need to remember about fuel gelling. Normally, the first indication is the formation of ice crystals from condensation, like an ice cold glass of beer on a hot summer day. Next paraffin wax appears; last and least (if at all) gelling occurs. The filters are the first place gelling is seen, perhaps after a cold weekend when the truck has not run enough to send warm return fuel from the engine to warm the fuel in the tanks.

All of this can be attributed to maintenance of the vehicle, storage tank maintenance, truck fuel tank maintenance and understanding fuel and maintaining dialog with the fuel supplier—“after all everything can be solved with an additive”—not so! There is a point at which you need kerosene. Also, truck stop fuel may not be additized, or blended. Pour depressants and additives work to a point, but kerosene is expensive and most truck stops do not blend because it cost too much.

Is it amazing how fleets way up in the northern United States and Canada do not have any issues with fuel. They have figured our how to maintain their fuel below ground, above ground and, most importantly, on the ground—and the suppliers refine it differently—what a surprise.

So when gelling is used as an excuse for fuel problems and the reason engines quit running, I would suggest that you better dig for the real causes. While it is rare, some fuel problems may be caused by sludge, crap, wax, water, amoebas and/or asphaltines. It is true that ultra low sulfur diesel (ULSD) fuel is more susceptible to cold weather influences, but the filters are doing there job, filtering.

For more information, visit or email comments or questions requests to Darry at: [email protected].

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