Now with this 99 Vulcan Ultra Classic, I have replaced the gasoline plus added a bottle of Mechanic in a Bottle as well. Plus new plugs, and new battery. It turns right over just as easily as it always did , but just wont hit.

  • “Replaced the gasoline” in the tank only? Or flushed system from end to end? So fresh fuel is getting to the combustion chamber?
    – Solar Mike
    Apr 18, 2021 at 10:31
  • 1
    Welcome to Motor Vehicle Maintenance & Repair! Have you tried shooting a small amount of starting fluid or even carb cleaner down the intake? If it fires at all doing this, you know it's a fueling problem. If it still doesn't fire, it doesn't eliminate fuel, but it does lean you towards the spark side of things. Apr 18, 2021 at 15:38

1 Answer 1


The 1999 Vulcan 1500 has a carbureted engine and carburetors are often damaged by sitting with fuel in them. Since you said you "replaced the gasoline" that leads me to believe that you also left the gasoline in the fuel system during storage. That is almost certainly the problem here.

When Ethanol-containing gasoline is left it sit, it immediately begins to absorb water from the air. As this continues the Ethanol and water solution separates from the gasoline. Since an Ethanol + water solution is heavier than gasoline this settles to the bottom of whichever part of the fuel system we're talking about.

Ethanol is a very corrosive substance and it attacks just about anything it is in contact with including metal, plastics, and rubber parts in your fuel tank, your fuel lines, your fuel pump (if present), and your carburetors. Carbs are full of small and vulnerable metal, plastic, and rubber parts.

Over a few weeks to a few months, the solution evaporates leaving behind a sticky "varnish" that will eventually solidify and clog up the works.

So you have two problems:

  1. Sticky and/or hardened material plugging the small openings in your carbs.
  2. Potentially corroded metal, softened or eaten-away plastic, and softened rubber parts in your carbs.

This is a perfect recipe for a problem with getting the engine to start.

But the basic process here is exactly the same as it is for all "cranks but won't start" situations. Check that you have air, fuel, and spark getting to the combustion chamber.

I'm betting that it's the fuel that is missing. Once you determine that's what it is, the next step is to service the carburetor and fuel system.

  • This is a beautiful answer. I'll remember this debugging method for every problem I come across with a combustion engine.
    – Hacky
    Apr 19, 2021 at 11:12
  • great answer! +1 -NN Aug 15, 2023 at 22:38

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