“My motocycle’s engine is not getting fuel? What’s going on?”
It’s not that you’ve run out of it – you know that there’s fuel in your fuel tank.
It’s not that there’s a leak either – you’ve triple-checked, and there are no puddles around your bike.
But even if you’ve got a fuel tank filled to the brim and your fuel system is leak-free, something prevents fuel from flowing through to your engine.
And in this article, you’ll discover 5 common reasons why your engine isn’t getting any fuel.
- Reason #1: The Petock or Fuel Tap is Set to “Off” (Carburetor ONLY)
- Reason #2: Your Carburetor’s Jets Are Clogged
- Reason #3: The Float Bowl Is Stuck or Has an Incorrect Height
- Reason #4: A Faulty Fuel Injector And/Or Faulty Fuel Pump
- Reason #5: Contaminated Fuel
Reason #1: The Petcock or Fuel Tap is Set to “Off” (Carburetor ONLY)
Perhaps it seems too obvious, and that I’m just being a big jerk to you, like I’m saying – “well, obviously the it has to be set to “On,” knucklehead!”
But not every “issue” is caused by a complicated mechanical failure – sometimes, the source of your problem is as simple as this.
And fortunately, the solution is as simple as the “issue.”
If you’re running a bike with a carburetor, you need to remember to set the petcock (or “fuel tap” if you’re in the UK) to “ON” before you get going.
Now, the fuel should have no problem flowing to your engine – unless you’ve got one of the other issues.
Would you like to discover more about the petcock? Feel free to check out Episode 29 of the 30 Minute Motorcycling Podcast:
Reason #2: Your Carburetor’s Jets Are Clogged
But even if the petcock is set to “ON,” the fuel doesn’t just flow straight from the fuel tank to the engine.
If your bike has fuel injection, the fuel passes through the fuel injectors first, which then gives a precise dosage based on the information from the ECU.
If your bike has a carburetor, the fuel passes through – you guessed it – the carburetor.
Specifically, it passes through one of the 3 carburetor jets, depending on how much wide open the throttle is:
- The pilot jet – 15-20% throttle
- The needle jet – 20-80% throttle
- The main jet – when the throttle is near wide open
Assuming of course that the jets are not clogged up. If they are, your engine will get an improper fuel mixture.
Although the engine might receive some fuel, it’s not enough. That’s why a clogged carburetor jet often causes your engine to not run as well as it should.
Reason #3: The Float Bowl Is Stuck or Has an Incorrect Height
That yellowy thing you see in the picture above you is the carburetor “float bowl.” If you were to take apart your carb (like, say, if you were to clean it), you’ll find the float bowl at the bottom.
This float bowl has one particular purpose – regulating the carburetor’s fuel supply.
And the reason why it’s called a “float” is because it literally floats while the fuel pours into the carburetor. When it reaches a certain point, the float will seal off the needle valve to shut off the flow of fuel.
But if it’s wedged stuck on top of the needle valve, there’s no way for the fuel to flow into the engine.
If the float’s height is incorrectly set or adjusted, it’s a similar sort of thing. Your engine might get fed a bit of fuel, but it’s not enough.
Reason #4: A Faulty Fuel Injector And/Or A Faulty Fuel Pump
So far, we’ve only dealt with problems that affect carburetors. You might believe that the issue of your engine not getting fuel is just something that affects carburetted bikes.
If you’ve got fuel injection, you don’t need to worry about that, right?
Fuel injection is far more reliable – no need to worry about pesky petcocks and choppy carburetor jets that get clogged up.
Don’t be fooled though – even fuel-injected bikes can have fuel flow problems.
The difference is that with this type of fuel system, the fuel has to go through one or several fuel injectors.
And before the fuel can get there, it needs to be pumped from the tank through the fuel pump.
As you’ve probably already figured out, your engine will not get any fuel if the fuel pump stops working.
Even if the fuel pump works impeccably, it won’t do you any good if your fuel injectors are faulty.
This rarely happens, but fuel injectors can break down. To keep it short and sweet, some of the reasons why fuel injectors or the fuel pump won’t work are:
- Broken solenoid
- Clogged injector nozzle
- The fuse for the fuel pump has blown
Reason #5: Contaminated Fuel
This reason why your engine isn’t getting fed fuel is special for two reasons:
- It can affect BOTH carburetors and fuel-injected bikes
- The issue isn’t with any mechanical component but rather with the fuel itself
So ironically, even if you’ve got a full tank, if the fuel inside is contaminated, it could be the source of your problem after all.
But how is this possible? How does contaminated fuel affect fuel flow?
Contaminated fuel often contains dirt and debris, which are bad for your engine.
At first, though, you might not notice anything unusual. The fuel runs through your fuel system; as usual, non-contaminated fuel would.
Over time, however, running contaminated fuel can cause serious engine issues, like:
- Engine knocking
- Poor engine performance
- Rough idling
And aside from that, remember the previous issue we looked at in this article? The one about clogged fuel injectors and fuel pumps?
Running contaminated fuel can cause both your fuel injectors and your fuel pump to gum up.