If you are taking on the same risk as the founders (not getting paid unless the startup works), then you should have the same equity. If you have less equity, you should be getting paid.

Your personal risk tolerance is up to you, but the founders cannot have it both ways. They must compensate you in cash or equity, not just set up promises for the future. There may be legit reasons they cannot give you equity or cash - but in that case, walk out with dignity and tell them to call you when they are able to give you fair compensation.