Boom Vader Vapor Lock? No, But No Fuel? Yes!

Well, my Boom Vader Gen 2 motorcycle has gone through some troubled times, right out of the box ( Boom Vader / Grom Clone Assembly Problems & Concerns ), during the first couple of rides ( Boom Vader (Chinese Grom Clone) Review (First Ride) ), and including the leaky gas tank ( My Boom Vader Gas Tank Is Leaking From Bottom, Again!?! ). However, my Boom Vader has a problem with losing power or even stalling when riding for an extended time. The web says it’s vapor lock ( Let’s Talk Motorcycle Engine Vapor Lock ), but I didn’t think so ( Boom Vader Motorcycle Engine Vapor Lock, What? ). Nonetheless, the Boom Vader wasn’t getting any fuel, and I have tested it.

NOT Motorcycle Engine Vapor Lock!

I had a loss of power conditions regardless of the outside temperature, and I lost power even with fuel lines safely routed away from any heat sources. My Boom Vader motorcycle had gremlins, and I was going to find them. 

How I found the source of the problem was purely by accident.

Draining The Gas Tank, I Filled My Head.

With the gas leaks coming from the bottom of my motorcycle’s gas tank, I had been filling and draining several times, testing my solutions( Boom Vader Gas Tank Repaired (Again?)! ).  

After a few gas tank drains( How I Drained My Motorcycle Gas Tank (My Carbureted Grom Clone) ), I noticed something. The gasoline poured much faster when the gas cap was off.  

So much so that I made the mistake of thinking the gas tank was empty once when it wasn’t. The flow of gasoline out of the fuel line trickled to a stop. 

I opened the gas cap to check the level and gas flow restarted out of the fuel line. The gas tank had a vacuum from the draining gasoline, preventing the flow of additional gas.

What Happened? Gas Tank Vacuum? No Gas Flow?

I confirmed my suspicion while trying the fix the gas tank leak( My Motorcycle Gas Tank Leak Repair Job ). I had the body panels of the Boom Vader, so there was no possible way to pinch any tubing.

One time I was draining the gas tank; I disconnected the vent tubing before entering the charcoal canister. The fuel flow was slow. So the problem was between the charcoal canister and the gas tank vent.

Boom Vader Gas Tank Valve.
Boom Vader Gas Tank Valve? Actually lost how this works, since air/gases should be moving in both directions.

This little black item is between the gas tank and the charcoal canister. It looks like a check valve and does not know its name, so that I will call it the “black button,” but I could figure out how it worked. The flow of gas fumes should go to the charcoal canister, but airflow into the gas tank should prevent a vacuum.

Regardless, I disconnected the gas tank vent tubing from the little “black button,” and TA-DAH! The flow of gasoline out of the fuel line was like a mighty stream. The flow of gasoline was almost indistinguishable from when I had the gas cap removed from the gas tank.

It seems the Boom Vader motorcycle would be starved of gas flow longer it operated because a vacuum would form in the gas tank. The gas tank vent was not working correctly.

My Gas Tank No Fuel Solution, Well, Maybe…

I am still working on getting my gas tank fixed, so I will cross this bridge when I get there. I plan on venting the gas tank, but I don’t want my garage filled with a gas smell from an open vent.

Boom Vader Motorcycle Gas Tank Vent.
Boom Vader Motorcycle Gas Tank Vent. Gas flows fast with tubing removed, but so does gas smell into my garage.

The jury is still out with me on how I can fix this. I wonder if I should remove the “black button” and directly connect the tubing back to the charcoal canister since the charcoal canister has a vent on its side.

Heck, not sure where to go with this. Please comment below if you have a solution or an idea to vent the Boom Vader’s gas tank and prevent gas smells from filling my garage.

Mystery solved, no engine vapor lock, but faulty vent device on the gas tank.  

Vapor Lock / Motorcycle Gas Tank Vacuum Update.

When I did the Boom Vader 125cc Carb Upgrade, I changed out much of the exhaust and intake system. This upgrade allowed me to replace the clogged parts with a one-way check valve vent. (Vent air into motorcycle gas tank).

This way, the gas/gas fumes remain in the motorcycle gas tank, preventing the gas tank from developing a vacuum. No more what people call “vapor lock” on my little Grom Clone.

The bike is more reliable now—a nice little upgrade to the tremendous upgrade to the Carburetor and Boom Vader exhaust system.

Here is the part I used:

Gas Tank Fuel Cap Valve Vent Breather Hose
Little vent check-valve cap that stops gas tank vacuum seals tank fumes inside.
Vacuum breaking vent cap installed on Boom Vader Gas Tank.
Vacuum breaking vent cap installed on Boom Vader Gas Tank.

Author’s Notice: This page contains affiliate links, for which I may earn a commission by their use. Also, as an Amazon Associate, I earn from qualifying Amazon purchases.

It comes in various colors, but the gas tank vacuum breaker is hidden for my installation. But I still picked blue; go figure.

Click For All Colors:
Gas Tank Fuel Cap Valve Vent Breather Hose CNC For Motorcycle Bikes

Thank you, Ride Safe, Ride Fun!

Click To See My Recommended

Boom Vader Gen 2 Upgrades

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.

4 thoughts on “Boom Vader Vapor Lock? No, But No Fuel? Yes!”

    • Hi Mike,

      Thanks for stopping by.

      I ‘fixed’ the gas tank venting issue while removing parts during the Boom Vader carburetor upgrade. It’s near the end, but let me recap the process.

      I removed all items off the vent and routed the gas tank vent tubing so it wouldn’t be kinked or compressed, and at the end, I put a one-way gas tank vent valve.

      Boom Vader Gas Tank Vent Cap

      The gas tank one way vent cap is the blue item at the end of the rubber hose.

      This vent valve keeps gas fumes trapped in the tank, but as the gas level lowers using the motorcycle, the air is allowed in like a vacuum-breaker.

      This help?



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