This not an easy situation to resolve amicably. It sounds like the team either don't realise that you have been given a new, non-development role, or don't understand the purpose of the role sufficiently. A PM should not be getting involved in development: that much you have stated. It sounds like the team want you to be a technical lead, which is a very different role from that of the PM. If you have a senior person on the team who could take on the role of technical lead or lead developer, you should consider making that role formal and directing the team members to him or her when they have technical queries. By doing so, you are demonstrating that you are outside the development team, and that your role is different from theirs. That then raises a new issue, which is that you could lose their support, which could prevent you and the team from achieving the project's goals.
I'm concerned about the comment that someone has been bitching with other members of the dev team and to your boss, without being told by your boss that your role is something other than a developer. The boss should be fully supportive of your role, and fully aware that it isn't a development job - so if the boss isn't backing you up, he or she is part of the problem. Try a heart-to-heart discussion with the boss, and check that you are both on the same page in terms of your role. If you are, you have support - so ask for it to be demonstrated. If not, then you need to align the expectations, otherwise you will never solve the problem as you will be "got at" from above and below.
One possible avenue to consider might be to ask the team what they see as the PM's role, as opposed to a technical lead's role, and offer them your view of the PM's role. Build on any commonality, and explain the purpose of any aspects of the role that they don't understand. Show them that these tasks need to be done, so if you are not doing them, then the responsibility will fall to the developers. That might just scare them, as in my experience, developers don't like to also be administrators, governance specialists, or progress reporters.
There are several other questions that cover broadly similar themes, so it might be useful to review these answers too:
How technical should a Project Manager be?
Splitting PM responsibility between technical lead and non-technical PM on an agile project?
Do technical leaders compete with project managers?
Role of a technical project manager?
Advice for a Non-Technical Newbie Scrum Master
How much technical experience is required to be a software project manager?
There are others, but these may help give you a flavour of how other people see the issue.