Changed Hoses, Thermostat and Spark Plugs, Cranks won't fire

[Anduha80]

Hi Guys,

First time poster, I have gotten a lot of useful information from this forum so just seeing if anyone has a tip. I am working on my friend's 1990 300ZX non-turbo. It was leaking coolant from the upper return hoses but ran. I replaced the hoses and the thermostat and installed new nozzles. I also cleaned the connectors on the ptu and put a small amount of connector protector (dielectric grease) on the connections. I made sure they were snug. I also cleaned the connections on the cam angle sensor and noticed the previous owner had broken the clip and was holding it on with electrical tape. I put it back on the best I could after cleaning it but it def is not spec. While I was in there I also replaced the spark plugs. The previous owner had three different types of spark plugs, there was no oil in the holes. All of the coils and boots looked good and I applied boot protector. The connectors for the coils however were all broken plastic but like I said she fired before. I put everything back and had to get a new battery as the old one died while working on the car. Anyway the car turns over but won't start now. Everything is back where it should be. Any ideas of what could be causing this? I was going to start a t the ECU and ignition fuses and work backwards from there.

[t.mcginley.jr]

You can check for codes, but there might not be any since the battery was dead for so long.

Anyway, I can almost guarantee that either the PTU or CAS connectors not making good contact is causing this. Have someone try starting the car while you wiggle the CAS connector and see if it tries to start. Do the same thing with the PTU connector(s). By the way, does it have a old or new style PTU?

For reference:



Also, Z1 sells new connectors for all of these things:

CAS connector

Coil pack connectors

PTU connector

[t.mcginley.jr]

Also, which spark plugs did you install?

[nexus08]

Is there any spark? Haven't tried to check for spark on my Z yet, but with other cars you take out a plug and hold the pluged in plug to a ground and have someone crank it while you watch for spark. It helps if it is dark.

[300zxstanced]

I am assuming you removed the CAS in the process of changing the thermostat. Did you mark its original position? If you dont put it back close enought to the original position then the car may not start. Also recheck the connections on the CAS and PTU. I had a wire practically falling out of the (CAS) harness when I checked mine, also test the CAS and the PTU(especially if it is the origianl style). I would focus more so on the CAS and its harness first.