1990 240 sx

does it crank evenly? as unknown we should verify that the timing chain is in the correct location, this one has a distributor? if it does pull the cap, see if the rotor is all that, cracks show up as carbon traces and the little pushbutton in the middle should yield a bit but not fall out- the basics please air, fuel, spark, timing----kinda drivin' this burro backwards, eh?

the computer will know if your battery is old thru mis-baving badly, seen this on Datsun's before~Get a fresh battery 1990 is more than ten years old=kaput---get a brand new one reputable brand (not walmart)---the ecu will see proper voltage after cleaning off the ground terminals black wire to chassis and the 1/0 battery cable to the engine block as well. It is through reliable solid power (who's connections are clean for the job) that we can expect the computer to start co- operating with us~

yep...could very well be a cracked cap...like my associate Cody asserted---report back~