car just will NOT START

have 88 celica gt conv., was running fine. suddenly running erratic, then shuts down.have changed fuel pump, fuel filter... engine turne but will not start.
changed spark plugs, wires, rotor, distributor... still nothing

some1 pleeze help... need my car urgently here

do not know what to do now...

Checked the timing? Timing belt

am awaiting mechanic now... what would let me know this is the problem?
i think this is it...because the engine just turns and turns but no crank
tried to eliminate all else before going to that
am mechanically inclined...but NOT a mechanic!!!
thanx 4 quick reply

Check your oxygen sensor and also check vacuum hoses for any that may have come off. Also check for blown fuse or bad relay. Since it is turning you can rule out starter.

was 1 hose loose, fixed that...
will check oxy sensor
fuses are good..i think... switched efi fuse
and fuses under dash are fine... did i miss something?

Make sure gas cap is tight. Make sure no one has put a potato in your exhast pipe. Check the codes (owners manual tells you how) You have to short out two pins and turn ignition to run and count the sequences. On the onset, it seems you are not either getting spark or fuel is not making it to the fule injectors. You can try to reset the ECU by disconnecting the battery for 30 - 60 minutes. Take the distributor cap off and see if the rotor turns when you start it. Check ignition coil and ignitor if you can, careful, high voltage here.

just checked the timing belt... belt IS still on there...but there seems to be an awful lot of slack in it.. is this how it should be?
mechanic never showed and i am still trying to isolate what the problem is and what is needed to be done here
thans again 2 all who reply

Your timing belt should be pretty tight, it sounds like its come loose and jumped a few teeth, this will be why it cranks but wont start, I wouldnt advise trying to start it again till you get it sorted, if it is indeed the timing belt, you may have had some piston heads/valves coming together, not good, this can bend valves, puncture cylinder heads etc, a compression test will be needed to tell you if everything is OK. You will also need a new timing belt.
Get it checked out by a mechanic or someone who is good at DIY mechanics before you go and buy anything.

According to Gates, the engine is not an interference engine and shouldn't have any damage from the timing belt jumping some teeth. Hopefully, all you have to do is replace the belt and the tensioner. Sounds like the tensioner gave out.

http://www.gates.com/downloads/download_common.cfm?file=TBR05.pdf&folder=brochure

thanx 4 all the help guys(gals???)
i am getting a mechanic 2 come check it 2day and w/luck-hope-prayer...this will be the problem.

will update when identified and fixed.

this is best site i have found 4 good intelligent help...keep it up

Please do not confuse timimg belt with serpintine belt. Timing belt turns the cam to lift the valves, the serpintine turns the AC compressor and alternator and water pump as well. this belt should also be tight, but you should be able to twist it a little, if it is too tight, it will stretch and break. Is the engine turning? Make sure the distributor wires are going to the correct posts on the dist. cap. If the sequence is wrong, this would be a problem. Let us know what the mechanic finds.

mechanic came by... apparentlt theres no spark coming from dist.
will be changing distributor... then we'll see
will update...

updated???

still no start... i still believe it is the timing belt...it is loose and slides... engine turns still but will not start... i changed the distributer....mechanis=c said it was a low spark...but i do not know what this means, and he did not really explain... so any further suggestions would be greatly appreciated...really do NOT want to junk the car...had really big plans for it...
thanx all...

1 more question... is this engine "free spinning"???
i was told to find out, but i do not know where to inquire...thanx again...

You need to check the timing points to see if the timing belt has slipped, some arrows on the timing wheels should line up with marks on the engine, if the timing belt is lose it will have jumped teeth, it will still be in place but out of sinc.

Dont know what free spinning means?
Maybe the same as an non-interferance engine, which means that the cylinders will not clash with the valve heads should the timing belt snap.

thats what the mechanic said.. that if the engine was free spinning, then it was a good thing... but how do i find if the engine is or is NOT free spinning???