Why Is My Motorcycle Leaking Gas?

As I pointed out in my last Boom Vader motorcycle review ( Boom Vader Motorcycle Review @ 400 Miles! ), I was smelling gas, and I was sure my Boom Vader Gen 2 motorcycle was becoming a typical victim of a slow stock carburetor bowl leak.

However, with the stopcock closed and I found the gas puddle under my motorcycle, it had me wondering real quick, why is my motorcycle leaking gas!!!!???? And then I found out something while I was searching why my motorcycle leaking gas on the ground.

Boom Vader motorcycle with catch basin underneath.
Having catch basins a must for motorcycle repairs and maintenance.

Even a tiny hole in a motorcycle’s gas tank can cause a mess with gasoline ending up everywhere. Gasoline only drains until its level reaches the leaking hole, but if the leak is on the bottom of the tank, the leak will empty the whole tank—what a mess.

On the Boom Vader Gen 2, the fuel stop is at the stock carb, and in my TaoTao TBR7, the fuel stop is at the gas tank outlet. This design means there is no stop valve to isolate a fuel leak on the Boom Vader up to the carburetor.   

The only gas leaks I heard my motorcycle might get was the carburetor—something I plan to upgrade later on with a much better carburetor.

This Is The Chonda Way.

How To Find A Gas Leak On A Motorcycle.

Okay, so I had a puddle under my bike, and it strongly smelled of gasoline.

The first step I took was to air out my garage. I opened my garage window to allow fresh air and the smell out. Gasoline is most dangerous in its vapor form, and I wanted the vapors gone. Also, I needed fresh air. The gasoline smell was potent.  

I then placed a pan under the bike to prevent the spread of gasoline on my floor. Weird how I found no active drips. The puddle was small, and the bike had not been ridden for several hours.  

I checked the fuel stop and was closed on the carburetor since that was the only fuel stop that comes on the stock Boom Vader, and it was closed.

Now the fun stuff, finding a gas leak on my motorcycle.

Warning: Gasoline is potentially dangerous, on contact and inhalation. Remember PPE ( Safety Glasses With Readers ) and basic motorcycle maintenance safety. Motorcycle Garage Safety Rules – FAQ

Not only is gasoline flammable and explosive, but it’s also toxic. Getting a small amount on the bare skin might not be too dangerous, especially if you wash it off quickly. But, I thought about my luck and took precautions.

So I took precautions since the gasoline leak was slow, so I had time to figure something out.

I used gloves, I usually have leftover gloves that travel home from my medical job, so I used them. I then used paper towels. The paper towels were white and clean, so they should help find that gasoline leak.

No, instinct says to check areas you know where gasoline is, meaning starting from the bottom, above the puddle on the floor, and up. However, I wasn’t interested in finding areas that were already wet. 

I wanted to find dry areas that lead into wet rooms. So I started high. Where I could reach, and it was wet as far as possible.

The Boom Vader’s body panels weren’t helping, so the panels would have to be removed asap. The gas leak wasn’t going to stop itself.  

If I drain the motorcycle gas tank, the leak will stop, I’m sure, but then I wouldn’t know exactly where the gas leak was.

I removed both side panels, but first, I removed the right side. The right side of the Boom Vader doesn’t have the seat lock, which makes it easier to remove than the left.

After removing the right-side panel, I did the same process, and I started wiping down surfaces from the top down with a gloved hand.  

It wasn’t long before I found the area where it went from bone-dry to wet and smelling like gas. The leak was somewhere on the underside of the gas tank.  

To confirm, everywhere under the tank was wet, including the engine. Not a good time to go riding. 😀

Just lovely, this is the Chonda Way!

How Do You Fix A Gas Leak On A Motorcycle?

First, have to find the exact spot where the leak is. Found the bottom side of my motorcycle’s gas tank is wet. Like many gas tanks, this is a busy section of the bike:

  • I have the outlet flowing gas down to the carburetor. 
  • I have the level sensor sending unit bolted to the bottom of the gas tank.
  • I have ever weld that can fail located on the lower section of the gas tank.

My TaoTao TBR7 I was concerned about my since many complaints are gas tank seam leakages. I avoided this problem by not cranking down the single TBR7 fuel tank bolt ( FAQ: TaoTao TBR7 Gas Tank Leaking From Bottom Problem ). I haven’t removed or tightened any gas tank bolts, but could another part of my Boom Vader arrive broken? ( Boom Vader Assembly Problems & Concerns )

Safety First!

Now I know where the leak is, and I have to get the gasoline level below the leak. Since the leak is somewhere on the bottom of the gas tank, I have drained the gas tank. Discussion about motorcycle gas tank draining: How I Drained My Motorcycle Gas Tank (My Carbureted Grom Clone)

An approved gas can.
Use an approved gas can for draining your motorcycle gas tank before fixing any gas tank leaks.

Time To Remove The Motorcycle Gas Tank.

Warning: Anytime you disconnect a line or move the tank, there is a possibility of additional gasoline leaking out. Collect it properly for safe disposal, and protect yourself with proper PPE.

After all the plastics are removed, the side panels and the gas tank cover, the boom Vader is held on by a single bolt in the front and two bolts in the back.  

There is a level sender quick disconnect. Disconnect this before lifting the gas tank.

A vent line can be disconnected at the top left of the gas tank.

If you haven’t already disconnected the fuel line from the carb, you can do that now or disconnect the fuel line at the bottom of the tank.  

Now The Motorcycle Gas Tank Is Removed.

Again, CAREFUL. Moving the gas tank can result in spilled gasoline, and examining the tank more closely could risk skin and eye injury ( Safety Glasses With Readers ).

I lifted the tank and looked for the ‘wettest’ spots on the bottom of the tank, and I had to wipe off areas and check for residual gas leaks. It wasn’t long before I found the site, and it was around the gas sender unit.  

Boom Vader gas tank underside, with level sender unit intalled.
Boom Vader’s gas tank underside, this is the level sender unit and gas is coming out from under it.

I’m done. I ensured the gas tank was emptied, recovering as much gasoline as possible with today’s gas prices, and put everything in a safe place.  

Added information for finding your leaking gas site:

I had some insight into a quicker way just to find leaking gas with these simple checks and put the steps into this list. Remember, this is a short list to see where your motorcycle is leaking gas and is not an expensive list.

My Quick Check To Why Is My Motorcycle Leaking Gas?

Gasoline is volatile, meaning it vaporizes very quickly. Hence, the gasoline molecules in the air often warn your nose of a gasoline leak long before a puddle accumulates and warns your eyes.

So I was smelling the gas long before I saw the actual leaking gasoline from the motorcycle.

I did the quick checks I learned about finding out why your motorcycle is leaking gasoline. Here are some quick steps to find the common sources of a motorcycle leaking gasoline.

1.- Motorcycle Leaking Gas From Carburetor?

The motorcycle carburetor is usually the lowest point in the motorcycle’s fuel system, and this position allows for gasoline to leak from the carburetor back to the actual motorcycle gas tank. Since gravity is the driving force for most motorcycle gas leaks, we start here.

FYI, some leaks stop when the flow of gasoline is stopped. This reason can be because all the gasoline leaked out of the gas tank, or the fuel petcock valve is closed. You might have to add fuel to the gas tank and/or reopen the fuel petcock valve to restart the flow of gasoline and find the leak.  

Be careful: Gasoline is potentially dangerous outside of an approved container.

a. The float valve could be stuck open.

Check the carburetor overflow ports and the inlet and outlet of the carburetor airflow chambers.  

Often the float could be misaligned, or the float valve might be stuck open by foreign debris. A tap might reseat a stuck valve, but dirt in the fuel could affect not only the float valve but also the carburetor jets. Check that you have clean gasoline and use a fuel filter.

b. The carburetor fuel bowl gasket could be unseated.

Like many Grom Clones, it’s no secret that the Boom Vader has a simple two-screw connection with no ability to tighten it. Check around the base and fuel bowl gasket area for any leaks.

2.- Leaking Fuel Petcock Shutoff Valve?

The connection between the more solid fuel shutoff valve and the thin-walled motorcycle gas tank is a point of failure over time. The flexing tank wall in contact with the none flexing petcock valve often wears any gasket material to the point of leaking. Check around the connections.

Also, check the petcock valve itself. The lever, or switch, for turning on and off the fuel flow can leak due to normal wear and tear. If so, it’s time to repair or replace the petcock valve.

3.- Leaking Fuel Line and Inline Fuel Filter?

With a carburetor, the normal flow of gasoline is driven by gravity. Therefore the fuel lines are under low pressure and often thin-walled.  

These fuel lines can crack and degrade with time, vibration, heat, etc… Check your fuel lines.

Also, since the inline fuel filter is designed to be disposable, it’s not made of the best/most robust materials. Therefore it too can fail. Check the connections to and from the inline fuel filter and the housing itself. 

4.- Leaking Gas Tank?

After you start from the lowest point to identify where and why your motorcycle is leaking gas, you move towards the largest gasoline source—the motorcycle gas tank.

Motorcycle gas tanks are thin-walled, have several penetrations, and might also have gasketed connections that can fail. Boom Vader Gas Tank Gasket ISN’T Leaking.

Check the gas tank for pinhole leaks and the penetrations for cracks or failing gaskets. FAQ: TaoTao TBR7 Gas Tank Leaking From Bottom Problem.

All else fails, drain the gas tank( How I Drained My Motorcycle Gas Tank ) and take the motorcycle to an approved mechanic. Not necessarily the Chonda way, but no need to risk a fire or lose the ability to ride your bike safely. Good luck.

Haven’t Given Up On The Boom Vader.

Nope, this is the Chonda Way!

I’m just putting everything down letter my garage air out and checking my warranty options. This Boom Vader is new, and so far, the seller (I will do a Boom Vader seller review later since many Grom Clone buyers are asking who to buy from) has been very communicative with me about other problems I found ( Boom Vader / Grom Clone Assembly Problems & Concerns ).

Check back later. I will have this gas tank leak problem under control in no time. 😀

Click To See My Recommended

Boom Vader Gen 2 Upgrades

Stock Boom Vader Gas Tank Leak UPDATE!

I was thinking about cleaning out the interior of my Boom Vader’s gas tank and retrying to seal it again, but I was losing ride time. I gunked up the inside of the gas tank with the J-B weld and figured I made it more challenging to seal it myself.

I wanted to try out one of those DIY gas tank sealing kits you read online.

So I went with another option, took my little motorcycle’s gas tank down to my local mechanic, and asked for a cheap and quick solution.

I did the nuclear option on my little bike:

Boom Vader Gas Tank Repaired Again(Now Welded)!

Picture of me, as a New Motorcyclist.
Just Me…Newly Licensed.

Hi I’m Tom, A New Motorcycle Rider and Blog Author.

I am a new rider(Pa Learners Permit at the end of 2020, and I received a Pa Motorcycle License in 2021 after passing a Motorcycle Safety Course).

I bought my first motorcycle, a TaoTao TBR7, at the beginning of 2021 and have been doing upgrades on that motorcycle since.

I added to my motorcycle collection by buying a Boom Vader Gen 2 in 2022, and that Grom-Clone motorcycle has been upgraded by me as well.

I continue to ride my Boom Vader Gen 2 motorcycle as well as my TaoTao TBR7 dual-sport bike.

Read more on my About Me page.

Fun Fact: I’ve only been on one group ride.

Leave a Comment