I just received my engine back from getting the head gaskets replaced. I install the engine and hooked everything back up. When I went to start it, it just cranked over. The engine will not start. I called the dealer and they told my to check the wiring and make sure I hooked up all the connectors. I checked everything and still it just turns over. There is spark fuel compression and all the connectors are hooked up. The engine keeps backfireing through the intake. I asked the dealer if they might of messed up on the timing. They said no. Does anybody know what my problem is? I still think it is the timing. I have a 2009 XTZwith 600 miles on it.