Help needed with MR2 starter problem

Try MHHAUTO.com they the best.

Make sure you have a good battery/connections. Make sure you have power down to the starter on the B+ terminal if not replace faulty wire or clean/dirty connectionson ensure connections are tight. While someone turns the key make sure you have power in the S terminal. If power make sure the engine isn't locked up and replace the starter. If no power you may have an issue with the ignition switch circuit (stitch, wiring, fuses....)

It could be a number of thing's , wouldn't think the battery cables or connections . If they were bad it would have started in the first place . Timing belt ! There again , it wouldn't start in the first place . The crank sensor would not have anything to do with the starter spinning the engine over . The fuel pump will only run for two seconds when the key is first turned on , this is to prime the fuel system ! The fuel pump will not be turned on again untill the engine is cranking , or running . The fuel pump is controlled by the PCM - engine computer through a relay (fuel pump relay) Samething for the starter control , has a relay . Testing for control of the relay ,.at the relay ! In the under hood fuse / relay box ! Find the starter motor relay an pull it out an look on the bottom , you will see four sets of numbers . 30 , 87 & 85 , 86 . 30 should have B+ volt , testing with a volt meter . 87 goes down to the starter solenoid . If you take a piece of 12 gage wire an jump these two spots in the fuse / relay box , the starter will engage if the battery , cables an the starter are good ! The other two 85 & 86 are the contol side of the relay .86 should have B+ voltage an 85 goes to the PCM , where it will supplie a ground IF ,there are no problems with the park neutral safety switch . Or also if your vehicle has a anti-theft system an no problems ! Also your vehicle has a relay called a ASD - auto shut down relay , this relay powers up a lot of systems on your vehicle , i would also check it , Relays do good bad .
How to voltage drop test starter motor circuit

http://www.bbbind.com/free_tsb.html free wiring diagrams , do you know what a wiring diagram is ? How to read one , to find testing points in a electrical circuit ?
Starter Voltage Drop
VEHICLE RELAYS Operation Diagnosis
Good luck i hope i have given you enough info to diagnose this correctly

Every clutch has a "throw-out bearing", and the proper term is Release bearing.

You should purchase a good quality complete clutch kit, and make sure that the clutch kit also comes with the pilot bearing as well. Be sure that they re-machine your flywheel to restore proper clutch operation.

Here is a link for you check out for yourself, and you can see that the release bearing and pilot bearing are both included in these clutch kits. You should then be able to purchase a new clutch kit from your local parts store.

http://www.familycar.com/store/?N=9191&Nr=OR(AND(make:Toyota,model:MR2,year:1986),AND(universal:1))&Vi=1725+11789+4294963916&y=1986&mk=Toyota&md=MR2

If you are talking the a/c pulley and alternator pulley, I am pretty sure the belts are different sizes (different number of ribs in the belt). So, you can just look carefully at the ribs and put the right belt on the right pully. from memory, the A/C belt goes on first and all the pullies towards the front of the car are used for that belt. The Alternator belt goes on next, and all the pullies from the crank shaft toward the back of the car (from the crank pulley) go to that. I could have those reversed, but the ribs on the belt will show you for sure. have fun!

Sounds like the starter went ban and there's an internal short in it.

Don't worry I'm sure you will get the solution of your problem, just check the link I attached
Toyota MR2 1983 1998 Workshop Service repair manual

Check all the wiring connections that you loosened or took off when you removed the head. something is loose or disconnected ,eg., ground wires .
Make sure you have spark at spark plugs whemn cranking ,and fuel pressure.
Did you try spraying starting-fluid in the intake, see if the engine runs for a little bit.
Compression to be anything above 100 psi will firean engine ,sometimes lower too.

http://www.fixya.com/cars/r7030578-engine_turns_over_but_wont_start

Please see this people

Try spraying starter fluid into the throttlebody...if it starts or fires, your fuel pump is bad. It will cost something around the $300-$400 mark to replace. Hope this helps!