Sometimes our model engines can be quite cantankerous. They do not wish to start or the engine will stall during operation.

If your engine is failing to start or is stalling during manuvers. The problem most probably is the fuel system.

This guide will walk you through the fuel system,step by step to resolve the problem with your engine.

1.Quality of Fuel

Are you using the fuel that is recommended by the engine manufacturer ? These are the folks who know exactly what the engine needs to function properly and at peak performance.

Example is a K&B outboard 11cc - They recommend NOT to run a higher percentage. The engine will far surpass its design capability when fed with 55% ! Do not run high percentage nitro in engines which were not designed for it. No matter if the appication is a plane,chopper,boat or car !

This can be one of the most common solutions when trying to run fuel with too much lubricant or too much nitro.

2. Too Rich, Too Lean?
Make certain you are not running the engine too lean (not enough fuel), or too rich (not enough air). When breaking-in an engine, you must adjust the engine slowly to get the right fuel-to-air mixture.

To adjust the engine to allow more fuel (run richer), turn the needle valve counter-clockwise, to allow more air (run leaner), turn it clockwise.

Try running your vehicle after each adjustment to test if this helped your engine run smoothly. If not, continue on with this guide.

Make sure you are seeing a small amount of smoke when your engine is running ! Running an engine TOO LEAN will result in catastropic engine failure.

Pinholes in fuel lines: Take fuel lines and tank to kitchen sink. Submerge fuel tank in water and blow into a fuel line keeping the other line pinched off. Did you see any bubbles in water? If so,then replace the fuel line or fuel tank,whichever was leaking.

3. Head Pressure
When the right fuel-to-air mixture is achieved, some problems will still exist. When the fuel tank is full, it is easy for the carb to draw the fuel, but as the tank empties, this becomes more difficult. This is determined by the air pressure in the tank, and the depth of the fuel in the tank itself. You can resolve this by pressurizing the tank with muffler pressure. If that does not work, you could opt for a smaller tank.

4. Fuel Lines
Fuel lines need to be as short as possible, and as straight as you can route them. Bends constrict the flow of your fuel. Too much distance creates Drag on the fuel the farther it must be pushed to the carb. If your lines are resting against other parts, the chassis of your vehicle, against the wall of a fuselage, it will cause vibration in your lines and possibly cause foam bubbles to form in the fuel. Try to make sure your lines touch as little as possible or are supported by foam.

5. Fuel Tank Location:
If your fuel tank is too far away from the carburetor, this will cause the fuel lines to be too long. Distance also can cause you to route your fuel lines around or through other objects. If you have a firewall, locate the tank (and the engine) as close to it as possible. For RC airplanes, it is best to mount the tank so that the center-line of the tank is within 1/2 to 3/8 of an inch below the level of the carburetor barrel. Level mounting is fine for surface vehicles.

6. Fuel Tank Mounting:
As with your fuel lines, your fuel tank needs to be isolated from the mounting frame, chassis, fuselage, etc. Make sure that your tank is mounted on foam, and thick enough to absorb the vibrations of the plane or vehicle. If the foam is too soft, or too hard, then it is not performing its function. So, make sure the tank is mounted firmly enough so that it does not shift during turns, but is not so firm that the foam is compressed, rendering it useless.

7. Adjust Carburetor Location
If you cannot lower your fuel tank, then try to lower the carb to maintain the distance mentioned in step 5. High G Forces can cause your fuel to splash and move around, so you want the fuel to have the 'easiest' path to your carb at all times. It is not always easy to move either part, but most kit designs allow for some adjustments, such as those mentioned here.

8. Ask for Help
If you still cannot determine why your fuel system is bad, take your RC vehicle to your local hobby shop and let an expert take a look at it. Sometimes the most simple issues can be overlooked. Other times, it is simply a tricky problem that will take time to iron out. It is best to locate the problem early, before too much damage is done to your engine.

Tips:

1. Always break-in your new engines properly. There are many ways to do it "wrong" which will cause damage to your engines. Read all your instructions carefully with each new engine, and never assume you know "enough" to get by. Nitro engines are too expensive to be too proud to do it right.

2. Check your engine settings each time you take it from storage, and before you start it up. This will allow you to catch potential problems before you do damage on start up.

3.If you are using a pull start, do not use the string as a yoyo trying to start it by yanking it 30-50 times in rapid succession. This will damage your engine. If others do it, great, that is their problem. But you should not get into this habit yourself, unless you have the money to waste replacing engines.

4. Check the fuel lines and fuel tank before each refuel. Look for cracks to the lines and tank, or for foreign matter, air bubbles or foam inside the fuel system. If you find damage, replace it before you continue on operating your vehicle. If you discover foam inside your fuel system, empty it out, and wash it with a small amount of fuel to remove it.

5.If you have no idea how to perform these steps, or you cannot resolve the problems, don't hesitate to ask an expert (send me a message) or take it to your hobby shop for repair and maintenance.

What You Need:

Proper Fuel for your vehicle.

The instruction manual that came with your nitro engine.

A clear sunny day. Soggy, wet days are not the best for fuel troubleshooting.

                    Various RC Tools needed for your particular engine.

Hope this solved some of the fuel system problems with your models.

Please cast a positive vote for this guide if you found it informative !

Have a great day and buy SOMETHING from me would you ?