The Cummins Westport ISX12-G and Eaton UntraShift+ 10-speed AMT have been a great combo to power my second Freightliner Cascadia CNG truck and have made it an absolute pleasure to drive in representing the CNG truck world. The quietness of the cab interior and superb handling of the Cascadia have really made an impact on my long workdays here in Southern California. I did however think of a common problem that stems from the fueling network for CNG fuel itself, but it is not the problem most think of when it comes to CNG, which is typically running out!
When most people think of CNG fueling, they think of a lack of actual stations available to get fuel, which has gotten much better over the years I have been driving CNG-powered trucks. As the network of fueling stations increases, more and more people are gaining access to this fuel supply. Here in Southern California, we happen to have one of the largest and most accessible networks, thanks to the CNG automobile boom over the past couple decades.
Before big trucks starting fueling at public CNG stations, fuel stations were mainly focused on fueling taxicabs, city/state/county municipal vehicles and public transit busses. Where most bus companies installed their own private fueling stations, the rest of the users relied heavily on private/public partnerships for their fueling stations. These stations did the job well of providing a much needed network of fueling for CNG vehicles here in California, but were designed to pump out much smaller quantities of fuel than what is used by the big trucks fueling in today’s CNG market. Many of the compressors at these stations, which are relied on for pushing the CNG into the tanks themselves, are often not adequate for the large volume needed for fueling heavy-duty trucks. This can lead to them being overworked, causing them to be very slow and even break down.
I caution anyone in a CNG truck to exercise caution when using some of these older/smaller stations, as a serious problem can occur from using them. Something that is becoming more prevalent and feared in the CNG community is the leaking of oil from these problem compressors, which then enters into your truck’s CNG fuel system. Even though there are filters on the engine that are drained daily for just this problem, issues can still arise from failure to do so and/or continued usage of these problem stations. The presence of oil in your CNG fuel can lead to a very, very costly fix on your engine!
Be sure to time your fills when fueling, since speed is a key indicator that a station has the right sized compressor for your needs. Getting a pump speed of 8-12 gallons per minute is a good indicator that a station has the “right stuff” going for them to fuel large trucks without a problem. Also, make it a habit to drain your two spin-on fuel filters that run any trace oil out of the system daily, as recommended by your owner’s manual. If you start to see traces of oily sludge or moisture coming from the bottom of these drain valves, discontinue use of your most recent fueling station and see if it makes a difference. Observe a station before using it, since they may look run down because the upkeep and maintenance are not quite what they need to be. By practicing these fueling habits and knowing what to look for, you can help keep your truck’s fuel system running problem-free for miles to come.