I think that the Bible is not clear enough on this issue. All effort should be made to prevent suicide and we should never advise a potential suicider that they will not go to hell. Saying that suicide victims are in eternal hell is unwise as it has the potential to dishonour God's name and may well steer people away from Him.
Agreed! However, scripture also does not say that those who commit suicide will not end up in hell.
I look at it this way: as believers in Christ, we are called to take up our crosses daily, which means that we are to keep our testimony of Jesus and the word of God regardless of whether God allows us to be persecuted or even put to death. That said, committing suicide is an attempt to escape whatever issues are confronting an individual. Every other trial and tribulation would therefore be less. Suicide would be an abandonment of faith.
The bottom line is, why would anyone want to test God on that? Because, if one who commits suicide does end up on hell, then there is nothing they can do to change that and no one to complain about it to.
The majority of unbelievers who commit suicide do so because they believe that once they die, they become non-existent, fade to black. But according to the word of God, we know that this is not the truth. For those who die in Christ, their spirit departs and goes to be in the presence of the Lord. In opposition, when the unfaithful die, their spirits depart and go down into Sheol/Hades to begin their punishment in torment in flame, where they will remain until the great white throne judgment.
In conclusion, I would advise that there is the possibility of going to hell if one commits suicide and that because, as you said, we have no direct teaching on this issue. And you know what they say about assumption.
The believer who commits suicide is not trusting in Christ. And it is murder. The Lord certainly isn't going to say "Well done good and faithful servant."