Thread keeps coming out of needle when I start a seam. Only just started.

[Cheeseandbeansontoast]

Please can anybody help with this?

This has only just started after threading my machine needle with no problems at all previously.

Basically I'm threading the needle as usual, then pulling the threads to the rear, making sure there is a lot of thread along with the bobbin thread.
But as soon as I start to sew a seam, the thread comes out of the needle.

The instruction book for the machine doesn't mention what could be causing this, my other book just says make sure there is an adequate amount of thread, which I do.
When the thread comes out, it looks like a short piece of thread which just sits above the needle where it's come out of. Any ideas? Many thanks in advance.

Is it snapping? Rather than the end pulling out?
If so, there are a few things to try/check. Check your tension on the machine, rethread it completely, and replace your needle.
If none of those work, try changing thread?
When it has happened to me I've usually found changing to a new sharp needle works.

Not sure. Only just changed my needle as the last one bent....
Just had another try and the thread only came out when sewing a few layers at the same time, but ok when just sewing 2 layers, if you see what I mean? Thanks for replying by the way.

Have you checked your tension? Is the needle the right size for sewing multiple layers? Sewing machines can be so frustrating!!!

It does sound like snapping due to tension. The manual will tell you how to adjust.