Possible Fuel System Problems and How to Avoid Them

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 Ask Dave / Posted 3 years ago / 1158 views

Question: What are possible fuel system problems and how do we avoid them?

Dave’s Answer: I indicated that 80% of engine failures are fuel related. Let’s go back to the fuel system starting at the front fuel tank and see what can go wrong. Fuel is being pulled by suction from the fuel transfer pump through the primary water/fuel filter to the suction inlet of the fuel transfer pump. At this point there cannot be any air present in the fuel lines on the suction side of fuel transfer pump. Why? Air in the lines may result in injector failure because the injectors cannot be cooled and will seize up, a very costly repair. Air in the fuel system will also cause cavitation of the fuel and a loss of power. Remember: Caterpillar electronic engine air/ fuel mixture is adjusted by the engine ECM. Air can get in the fuel line through connections or aftermarket water/fuel filters that are not maintained.  Rubber hydraulic hoses age and deteriorate and may cause leaks or residue in the lines. Motorhomes equipped with Gate Gobal  fuel lines are especially vulnerable. I have seen several that have started to fail after many years. The use of non-Caterpillar brand 2 micron secondary fuel filters may disable the ECM safety engine shut down. Inferior fuel filters may allow contaminants into the fuel rail requiring complete fuel system tear down for cleaning.

The fuel system is the most neglected area on a motorhome and is the most critical  to maintain trouble free operation. Last point to remember, low power on the road, will likely lead to a fault, reporting injectors number 5 or six are bad. A service shop will probably change out the failed injectors, or try to sell you a complete set of new injectors and other parts. The owner will pay for the repairs and leave, but the shop has not fixed the problem. Power will be a little better at first, but still not what it should be after dropping a big amount of money. What is wrong with this picture? They did not address the air present in the fuel system. Somewhere between the front fuel tank and the fuel transfer pump there is air entering the system. You are again headed for injector failure. The service shop will be quick to point out injector failure but In all likelihood will not realize the real cause of the problem, and will not check for air entry into the suction side of the system.

To avoid these problems it is important to use the correct Caterpillar fuel filters. You should carry a spare fuel filter at all times in case your maintenance facility does not have one. Use clean diesel fuel and always  store your coach with the fuel tank full. It is a good idea to check over all the fittings on the fuel lines for leaking or loose movement at joints. Replace old and hard fuel lines.  Check the fuel system for air yearly (I will explain how to do this in an upcoming post.)  

Last point to remember, fuel system parts cost very little to repair and maintain … much better than the costly repairs that will result for lack of maintenance.

Dave

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