More trouble!

[ffBrian]

Hey there, for those of you who responded to my previous questions, thank you very much. I have a 77 280z, that I finally got running! My problem now is that it is running far to rich. I have good fuel pressure, new air flow meter, new fuel filter, new alternator, new cap and rotor on the distributer, new plug wires and a new coil... I am fuel fouling plugs in about 2 minutes, the exhaust is terrible (black and white smoke under power, white smoke at idle, car actually blows excellent smoke rings!) The car lacks power most of the time, unable to even back into my garage anymore, problem is steadily getting worse (car actually drove well around the block earlier)... Gone through 3 sets of plugs, out of ideas, please help!

[Ronald Whitaker]

You need to take a compression test, Check for water in cylinder, valve timing can also cause poor combustion. Compression test first

[Z train]

Cpmpression will not effect a black smoke issue.Take the plug off the computer and make sure it's clean.Same with ALL connections.

[IdahoKidd]

check for "thermotime switch" in the search function or in the manual. I can't recall off the top of my head, but I think it fuels for cold start. Check the connections to the two sensors in the very front of the motor. One is the temp sensor, the other the thermotime switch. You might try unhooking the cold start injector plug so it can't put fuel into the system too.

[ffBrian]

thanks to all, i have not done a compression test yet, unplugged the cold start injector with no change in performance. Does anyone know if this car has an O2 sensor? The book doesnt specifiy (Chilton). Could this be the problem? Cleaned all connections, no change...

[Zed Head]

The water temp sensor tells the ECU how long to open the injectors. The colder it is the higher the resistance value. If it goes bad, giving infinite resistance, or you have a broken connection it will tell the ECU that your engine is stone cold and the ECU will continue to pour on the gas.

Page EF-23 and EF-32 of the 78 FSM describe the test procedures (sorry, the 77 FSM is too hard to find things in). Measure across Pin 13 to ground. If you get infinite resistance you probably have a bad sensor or a bad connection. Resistance should be about 2.5 k-ohms at 70 F.

76 uses Pin 13 also so it's a good bet that 77 does too.

The thermotime switch just cuts powers to the cold start valve if the engine is warm or if it's been cranked over recently, I believe.

[sblake01]

You'll need to use the 77 FSM to troubleshoot a 77. There were enough changes in 78 to where it make things confusing. (internal regulator, no fuel pump contacts in the AFM, etc.) You would actually need to remove the fuel line from the cold start valve and plug it to be sure it's not leaking as it could leak with or without the electrical signal from the thermotime switch. No O2 sensor on an S30. I would check the water temp sensor first as Zed Head suggested, however. Here's a link to a 77 FSM.

http://www.xenons30.com/files/FSM/77_datsun_280z.zip

[ffBrian]

thank you very much, both for the link and the advice. I suspected that the water temp sensor worked that way, but I wasnt sure. I'll let you guys know how it goes this weekend!

[ffBrian]

Thanks to all who helped. The car is running well now! I replaced the voltage regulator (the charge light was on and the alternator is good) and the water temp sensor. It has never ran better in my experience! Thanks again