For getting the complete functionality of blockchain networks, Hyperledger Fabric requires 66% of all nodes in the network to be up and running. This is the minimum requirement of nodes whose validation is required for approving requests.
You can check the pBFT consensus algorithm on a four-node blockchain network by leveraging the Start Developer plan or High-Security Business Network Plan.
However, you must note that the blockchain network cannot allow more than one Byzantine node.
For each network containing N=4 nodes, Maximum number of Byzantine nodes: f=(4-1)/3=1
When f>1, the pBFT 4-node network does not guarantee consistency or integrity of the whole ledger across all nodes that pertain to it.