My elmark ceiling fan with remote does not work on high speed and works only on low speed. On high speed it starts and stops immediately after a few seconds. What could be wrong?

I suspect the control board for the remote in the fan is defective.

Try locating your fan here:

Welcome To Elmark Marketing

And try contacting the manufacturer for parts. Good luck with that.

Thanks... I contacted Elmark and they suggest it could be the capacitor problem. What do you think?

True, but unless the fan has pullchains, the capacitor will be in the receiver.

Get them to send you the parts you need.