I have a 1990 240sx that wont start i know what is causing it to not start. the fuel injectors arent getting a signal and therefore arent being pulsed but there is definatly fuel pressure at the injectors. as far as i can tell there are no loose grounds or anything like that. anyone have any suggestions?

 

dead ecu?

it's the only thing i can think of right now that would keep the injectors from getting a signal.

 

i already swaped it out for another one. ive been fighting this thing for a long time and i cant find anything wrong with it. i was wondering about the EGI relay if that was bad would that keep it from getting a signal?

 

^
the engine wouldn't turn over if that was the case but if you haven't done so already it's worth tiring.

what else dose the car do or fail to do when you try to start it?

 

everything else seems to work fine at firts i just assumed that it wasnt getting spark but it has spark. the ecu i put in was out of an automatic car of the same year i dont know if that matters.

 

the ecu's are interchangeable. so when you turn the key dose the engine turn over or is there just a click or not even that?

 

yeah it cranks and everything like it should

 

mass airflow maybe, is it getting some fuel. just a guess some people have that go out and the car stalls alot. just a suggestion.

 

Sorry to be inquisitive, but how do you know there is no signal to the injectors? Do you have a an injector node light?

I assume you check and see spark. If you do see spark, and through proper checking, there is no injector signal, it does either have to be a missing ground, power, or bad ECU.

Also, have you checked for codes and when was the last time the car ran?

 

yes i did use a node light and i also used a multimeter just to check and it has spark for sure (try and guess how i found out) the car has never ran since i bought it
(edit) i also got a wiring diagram and tested all the fuel related ports on the ecu with a multimeter everything seemed okay

 

Does it have power to the injectors. I assume from your edit, the answer is yes. It is possible although unlikely that the node light was bad and it is getting signal. I believe a multimeter is not responsive enough to pick up on the small short signal pulses for the injectors. In cars that do not run for a long time, the injectors can seize up. If this is the case, and assuming this is a twin cam, you can tap the top hat over the injectors using a socket extension and a hammer. You have to give it pretty decent and repetitive taps while someone is cranking the engine.

If this is not the case, sounds like a dead ecu

 

i guess i need to rephrase my edit i was checking for a loose ground when i was doing that i think the possibility of the node lights being bad is unlikely as they had never been used when i used them but i guess it is possible. the car is a SOHC ka24e. and i tried swaping the ecu out for another one but it didnt seem to help. when i bought the car it had a blown headgasket. and i originally thought that i didnt hook up a ground but i cant find a loose ground anywhere

 

ok lets go back in time a bit.

when you bought the car did it start?
i take it you already replaced the head gasket, did it ever start after that?

 

when i bought the car it would start not very well due to the head gasket. It has been started one time since it was done but it was on carb cleaner through the intake so i know it can run but it hasnt started on its own since i redid it

 

so when you spray into the intake it will start will it staay runing or does it shut right off. if it stay's runing vote out injectors.