Car spins but wont start - 1999 Nissan Maxima

Won't start how ? When you turn the key to the start position does the starter spin the engine ? Or not ? This would be a no crank - no start condition ! Or when you turn the key to start the starter spins over the engine but it doesn't start an run ? This is a crank - no start condition . Both have very different diagnostic testing procedures ! An what won't say anything ? Is there a car an padlock symbol lit on the instrument cluster ?

I would say check your intake. First guess. Hopefully you didnt warp your heads.

I would check my timing belt/chain if the belt has broken or skipped teeth your engine willact like it has no compression because the valves are not working properly to let air gas spark in when its supposed to.

Free spinning or does it sound like its trying to start? If its free spinning, timing chain possible. If its trying to start, look into the ignition system including crank and cam sensors. You will need a scan tool that read live data. Codes on the PCM or no?

Did you check for codes? there are so many things that will not let the engine start. fuel pressure, oil pressure, ipc, idm, ecm the list goes on.

You probably need a new starter ...

what do you mean "wont start" do you mean it turns over and wont start, or wont turn over?? belts dont just break, if the car wont turnover, take the belt off and manually spin every pulley with your hand, all should spin freely (except the large bottom crank pulley) you may find that one of them is siezed.

check your fuel filter you may have a clog somewhere if the pump works off the car.

The starter relay may be sticking on start. Get someone to start truck and when problem starts hit relay lightly wih hammer. A cheap voltmeter will tell you if relay is sticking or still energised from ingnition switch after key release from start position.

does it have fuel pressure? sounds like the fuel pump is not working to me.