No, it sets you in the direction you're facing. The only problem is setting a limit to how long you can jump for.
That's easy.
Set a variable on the player to zero.
Make an if statement detecting if the variable >= 1.
If false, then check for the jetting.
When the jets go, make it add 1, so this adds up as long as the jets are held. When the player stops jetting, make this variable set back to 0.
If the variable >= 1, use the velocity events.
Add another if statement that detects if the variable >= 100.
If true, have a delayed cool down using toggle events, and set back to 0 once cool down is completed.
Make sense?
Also if you have the SetEventDelay event, I think you can adjust the cool down length based on the amount of "fuel" that is used.