Preventing fuel problems in cold weather

greasytshirt

Moderator
Staff member
Mechanic
I've been asked my opinion on what to do when running in bitter cold, and how to avoid fuel gelling.

With today's ultra precise (and expensive) injectors, I'm leaning against running additives unless certain precautions have been taken. Most anti-gelling additives also have ingredient designed to remove water from the fuel system. That sounds good, but what's happening is the water is emulsified into the fuel, allowing it to pass through low-micron filtration and into the injectors, where it wreaks havoc.

The first thing that needs to happen is the water should be removed from the fuel system. Without using additives, this leaves mechanical removal. Fuel/water separators have this function, but water left in the tank isn't addressed. Tank draining makes a mess and the drain plug often isn't the lowest point. Something like this would work great. IPA Fleet Tank Sweeper — 1/3 HP Pump, 18 GPM Flow Rate, Model# 9049M | Fuel Tank Sweepers Cleaners| Northern Tool + Equipment
Unfortunately that thing is stupid expensive. A fleet might find it worthwhile, and it may pay for itself the first time it prevents a thousand dollar tow and late delivery. I bet a similar apparatus could be cobbled together out of stuff on ebay for a couple hundred bucks. Fuel filters should be changed much more frequently, especially on systems that have a single fuel filter of low micron count. Filters like this stop water from passing through them simply because the water droplets can't pass through the media. They just get stuck there. On the first day with a good freeze, this water will freeze on the surface of the filter media and no fuel will pass through it. This is the most frequent cause of cold-related, no-start, fuel restriction problems I've personally encountered. Not fuel gelling, but the symptoms are similar. The difference is that the problem wouldn't have occurred despite bitter cold if the filter was otherwise clean.

Water needs to be kept out of the fuel system once it's been removed. Filling the tanks to the top prevents area for condensation.

A tank heater is a viable option. There are electric ones and ones that run a coolant loop through the tank. Either of these would work if you're running an APU and you want the main engine to start after it's been off all night. Fuel return from the APU will also contribute a little to tank warming. Running a coolant loop from the main engine will definitely warm the fuel, but that won't help if the engine has been off for a long enough time for fuel to gel. Insulating the tank will keep it warm enough for hours to prevent gelling overnight. On Hino trucks, a large amount of warm fuel is constantly being returned to the tank, so once the engine is running, it would have to be unbelievably cold to gel the fuel.
Some trucks had optional fuel heaters built into the filter housings. It may be worthwhile to upgrade if your truck doesn't have one.

Fuel mileage will be worse, but running a mixture of #2 and #1 diesel is an easy method to prevent gelling. Something tells me that fuel suppliers in cold areas have a proper mixture of additives already in the fuel to permit cold weather operation, so getting the water out and keeping clean filters in would be my first strategy.
 

Tobster317

Expert Expediter
Owner/Operator
How do I know if my fuel heater in the fuel filter housing is working properly. Don't tell me to wait till I get up north to see lol.
 

greasytshirt

Moderator
Staff member
Mechanic
How do I know if my fuel heater in the fuel filter housing is working properly. Don't tell me to wait till I get up north to see lol.
It'll be powered whenever the ignition is on. It doesn't get super hot.
You will need a multimeter to check the following. Turn on the ignition. Unplug sensor. One leg from the harness should have 12v, the other should be a ground. Check the heater leads for continuity. I don't know what the value should be, but under ten ohms sounds reasonable.
 
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