Iginition Problems

[Vilmenay]

For the past week I've been trying to sort out my why my car won't start. Ran codes it says 55, cleaned and test the injectors, the coils and their connectors, tested and cleaned the cas it read 5-0 volts when you I spun it, heard the injectors tick, bought several TPU even one from the nissan dealership with the wiring harness, (the service manual on testing TPU I think is flawed) no spark at the coils when spark plug grounded. Have fuel going in and out. The engine is from a 91 the car and the ecu is a 90. Any thing else I should check?

[snwbrdr435]

the starter might be a good place to check

[Vilmenay]

I'm sorry I didn't mention that the car does turn over as if it wants to start so the starter is doing it's job it just does catch I took out one of the injectors put a ground in it no spark....I also found 12 volts of power going from the 6 wires that feed the PTU harness but the wires that are supposed to receive power from the ptu harness had voltage on them as well ranging from 7-1 even though disconnected from the ptu harness.

[Canyoncarver]

You might try checking & cleaning your ground connections. Even if you're getting power to the ptu, the ptu and coils won't work without a good ground. If you refer to the wiring diagram here: http://www.300zx.co.uk/cgi-bin...l=190 you'll see that the ptu & c/p ground goes back to ecu pin #116. You might check for continuity in that wire.

[Vilmenay]

Good idea. My question now would be, how would I go about checking continuity on a ground that's connected to the ECU? And if by chance I did confirm that was the problem how would I go about resolving it?

[Canyoncarver]

For checking the continuity, you can disconnect the connector from the ecu.

This is the only page in the online fsm that shows ecu wire colors and it's not complete. Hopefully you have a hardcopy fsm. http://www.300zx.co.uk/cgi-bin...tal=3 Basically, you need continuity from that black wire to the ground at the ptu. A fix would be to run a jumper wire.

The last guy that I chatted with, with a virtually identical problem, ended up buyimg a new efi harness which fixed his problem. I'm not suggesting that a new harness will fix your problem tho.