Engine starts with carb cleaner

Question

I have a motorcycle that will turn over but not start. When I spray carb cleaner into the carb and crank it the engine fires up. Does this mean that the engine is getting spark but not fuel and that I should continue trouble shooting the fuel system?

Answer 1

That does sound like a fuel supply problem, especially if the engine dies soon after. How old is the fuel? Have you drained the tank and added fresh fuel if it sat for a few years?

Here's how I would approach the problem:

• Make sure that the fuel tap is set to prime if it is vacuum operated
• Pull off the float bowl, assuming you can do that with the/a carb in situ and check if there's fuel in there
• Move the float up and down and check if there's fuels coming through

Note - most of the above is going to result in fuel splashing over the engine so I wouldn't do that in an enclosed space. Make sure you have rags to clean up the spill.

Once you've established if the carbs are getting fuel, you'll either need to figure why they aren't, or why the fuel isn't being drawn into the combustion chamber.

If there's no fuel or not enough fuel getting through, check the float height and make sure the check valve isn't sticking.

Also, some bikes (1st gen Goldwings are notorious for this) require a lot of cranking if they sat for a while with fuel in the carbs, even if the fuel hasn't gone bad.

If you establish that fuel is making it into the carbs but not into the engine, it's time to pull them and clean them. Or replace them, depending on how bad they are. If they're really corroded it can be almost impossible to clean them back into working condition.