I recently purchased a 1990 Nissan 300ZX 2+2 with only 13K miles. It required a trailer to get it home. I've worked on it off and on to no avail. When the key is turned to start, nothing happens. Fuel pump comes on for a second or two. I replaced the solenoid/starter even though the old one worked without hesitation on the bench. The security light flashes when a door is opened. I've locked and unlocked the car from the outside at the doors and hatch dozens of times. I've removed the anti-theft module, no help. The big wire to the solenoid/starter tests at 12 volts. The little wire going to the solenoid (at the nearby connection) tests 12 volts when the key is turned to start and the clutch pedal is depressed. Oughta' start, right? Oughta' at least spin. I've worked on cars fifty years but this has exasperated me. Battery is two years old and tests great. All the lights and windows, horn, all the electrical stuff works as it should. Couldn't find a '90 manual, so I bought a '91 and started on one of the trouble shooting flow charts but didn't get very far. Perhaps the pin out is different. The car will push start, pop start fine. Drives great like a car with 13K miles. Fantastic handling. I stand and stare at it, talk to it, yell at it, nothing seems to work. Thanks for reading this. I started a carpentry project just to have some balance between win and lose. These no spin no start symptoms are crazy.

Oh, I swapped out the anti-theft relay with another identical one, no soap.

Is this a USA model car? Have you looked at the blue starter relay in the drivers side fender liner?
http://twinturbo.net/nissan/300zx/tech/ ... relay.html

Have you checked that the little plastic grommet on the clutch pedal is intact and contacting the switch when depressed?

Does the starter try to spin? If you're getting 12v to the starter motor and solenoid then it should.

Yes, it is a USA car.
The new starter/solenoid never makes a sound when the key is turned to start. I've looked at the nearby connection for the little wire headed to the solenoid, looks great and put dielectric grease on it. Nothing helps this situation. I can dig out the starter relay today. I don't know how to tell good from bad though. I guess if it is passing electricity on the key turn, then it's good.

itsa300zx wrote: ↑

Wed Apr 03, 2019 3:02 pm

Have you looked at the blue starter relay in the drivers side fender liner?
http://twinturbo.net/nissan/300zx/tech/ ... relay.html

This is most likely your issue, had the same thing intermittently then nothing one day. Had the relay tested during repairs and came up intermittent again, then failed so was replaced and no issues since. I was also told the shop (Z/GTR/Nissan specialist) has been seeing a LOT of failed relays and solenoids from the entire Z car lineup, potentially another (infamous) Nissan electric issue coming about.

NolimitZ32 wrote: ↑

Thu Apr 04, 2019 5:57 am

Does the starter try to spin? If you're getting 12v to the starter motor and solenoid then it should.

^^^
This is what is confusing, if the starter relay was at fault, there should be no 12V at the solenoid.

Another guess would be a bad ground to the starter?? I would inspect all the heavy gauge wires to and from the starter and make sure they are all solid/corrosion free.

I thought of the bad ground idea a week ago as well. The starter uses the engine for its ground I think. I'll try to find the engine grounds today. I don't see a ground wire to the starter. The fact that I've got 12 volts when the key is turned to "start" at the solenoid is maddening. The power, the electrical push must be insufficient to make the solenoid work. Now, to find the grounds, should be easy. The car sat for years I believe as its first owner grew old.

I can't find the four grounds the manual talks about. E13, E22, M3, M90. I've looked, can't find 'em. The manual has nice pictures of the general area of where they are located. What I did find was a ground wire the manual didn't talk about. From transmission case to transmission support bracket (manual tranny). Good thickness, ending in a big brass ring on the bracket and a smaller brass ring on the transmission. The bracket is painted black and I thought, oh boy, this is it. The ground isn't connecting through that paint. I sand off all the paint, put dielectric grease on it, put it back together, tightening the connections which were tight to begin with. Get in the car, turn the key, silence. Nothing. There is no evidence of mouse damage.
Forty-five years ago I had a Datsun 510 wagon with a dim headlight. I changed out the headlight, no change. Puzzling. It had those cylindrical glass fuses in it. I checked the fuse, it was cracked seven-eighths of the way through. You could see the crack. I'm going to order the starter relay next. Maybe it's bad.

quick way to check the likely problem of bad pos cable to large starter lug (all other accessories and circuits are taken off a second wire that splits off battery to fuse links & fuse boxes) - what you do is connect one jumper cable (say red) clamped real good on positive batt post - other end of red jumper DIRECTLY on the large lug that's already supposed to be connected via that heavy starter cable . What that does is PARALELLING the B+in case the cars cable is not able to supply starter amperage , even though you HAVE seen a good voltage there - I'M an electrician. good luck
A bad heavy-cable starter run, was diagnosed this way on my car. I saved the $115 dollar "factory harness" and simply ran a second run , routed and secured well , with good lug connections for $19 (battery pos lug to starter stud). Made it start better than when I bought it.

^ This, how did I not think of this, I had this on one of my cars once upon a time, the cable was completely corroded on the inside and the voltage drop under load took it way below the threshold for spinning the engine. Good call Mac.

Very, very, well summarized in a nutshell NolimitZ32 , key phrase "below the threshhold" . I'm gonna remember that one .

THANK YOU DCaff300ZX. You rock, man. It was the starter relay. Car started on its own for the first time in years...And thanks to Itsa300zx and Macgiver, too. If you guys are ever driving on the Olympic Peninsula in Washington State, drinks are on me. I am so happy. This car is so flippin' fast and handles like its on rails. The fact that I had 12 volts at the solenoid when the clutch was depressed totally threw me. The relay was not passing enough juice. Who knew? You guys, that's who!!!

Dieter wrote: ↑

Fri Apr 12, 2019 4:31 pm

THANK YOU DCaff300ZX. You rock, man. It was the starter relay. Car started on its own for the first time in years...And thanks to Itsa300zx and Macgiver, too. If you guys are ever driving on the Olympic Peninsula in Washington State, drinks are on me. I am so happy. This car is so flippin' fast and handles like its on rails. The fact that I had 12 volts at the solenoid when the clutch was depressed totally threw me. The relay was not passing enough juice. Who knew? You guys, that's who!!!

Glad it worked out for you

If you think the NA is quick, wait till you have the itch for a TT swap.