may be use a super charger or a turbo charger
JEEP xD
There is no 3.1 engine in any Jeep
Replace the TPS (Throttle Position Sensor).
Dodge
First try the map sensor. If that doesn't do it, then the fuel pump should. It is normal for that generation of Jeep to have a longer crank time.
VM Motori
you flooded it
The starter is out?
The Liberty used a VM diesel engine, the Grand Cherokee has used a Mercedes and a VM diesel engine.
If the crank turns when you try to start the engine, the chain is likely broken. If the chain makes a slapping noise with the engine running it's possibly stretched. Otherwise, it should be OK.
you can have one installed aftermarket
Not knowing what year that Jeep is or what engine it has, start with replacing the fuel and air filters.