K guys, it's me again. Well i replaced the fuel pump, and the engine still won't fire!!!

Here's a list of all that has been done with the engine:-new fuel filter-new fuel pump-new air filter-new plugs-engine diagnostic showed nothing wrong-ECU diagnostic showed nothing wrong-compression test showed each cylinder at 135 psi-visually seen all injectors opperate properly-visually seem all plugs fire properly-timing has been check and was on time

What could be causing the engine not to fire???:help :help :help :help :help :help :help :help :help :help

135psi is very low. are you burning oil? how did you do your compression check?

i did my compression test with a compression tester, by screwing it into each spark plug hole (one at a time) and turned the engine over a couple times until the compression gauge wouldn't go any higher. i was burning a slight bit of oil prior to the engine break down that did gradually worsen up to the break down, but the burning oil ammount was very very low. like you couldn't even visibly see blue exhaust from the pipe. you could smell it a bit, and you could tell i was burning oil when i had to top-off the oil level ever 3 weeks. but that really wasn't anything major, cuz i only added about 0.5 litres every three weeks

one last thing, if 135 psi is far too low for each cylinder, then how many psi should they be??

1990 240sx (KA24E)

according to the FSM...

standard compression pressure = 192psiminimum compression pressure = 142psidifference limit between cylinders = 14psi

this is the procedure for checking your compression (again this is out of the FSM)

1. warm up engine.2. turn ignition off.3. disconnect fusible link for injectors.4. remove all spark plugs.5. disconnect distributor center cable.6. attach a compression tester to no. 1 cylinder.7. depress accelerator pedal fully to keep throttle valve wide open.8. crank engine and record highest gauge indication.9. repeat the measurement on each cylinder as shown above.10. if cylinder compression in one or more cylinders is low, pour a small amoount of engine oil into cylinders through spark plug holes and retest compression.

- always use a fully-charged battery to obtain specified engine revolution.- if adding oil helps compression, piston rings may be worn or damaged. - if pressure stays low, a valve may be sticking or seating improperly- if compression in any two adjacent cylinders is low and if adding oil does not help compression, replace cylinder head gasket.

hope this helps.

alright, i'll redo the compression test following all the steps you said, and i'll see what it does. my dad's gonna bring home some compression testers from work when he comes for lunch in about an hour...thanks for the help and i hope this works...