New Member and engine trouble

[Zrunner]

Hello all on Classic Zcar

I have been workin with Zs for a few years. I have a 76 280z and a 90 300zx. You will have to excuse me because I am still getting used to this forum layout.

I come to this forum in request for help. I have browsed the search funtion for help but i have not found to much to my liking.

My 280 ran solid for about a month after the rebuild and gas tank replacement. The injectors were also replaced early on. One day it started to run a little rich. It ran fine just a little rich. Over the next few days it got very bad. I drove it to school and it stopped idling. I sat in traffic holding the gas so it would idle. It was towed home that evening. I relizes that it most likely will be an air/fuel mixture problem. I need some guidance. I have not gotten it to run to check anything. If i could get some suggestions it would be awesome

thanks

zrunner

[DatsunZsRule]

What all have you checked? I guess I'd check the AFM (Air Flow Meter) to make sure thats functioning properly since that is basically the heart of the L Jetronic. The E.C.U. receives the signals from the AFM like the amount of air entering, air temp, ect. so if the AFM is worn out internally that will mess up your air/fuel mixture. If you have a FSM, (Factory Service Manual) I'd also perform the tests at the 35 pin connector for the E.C.U. with a multimeter

NOTE: Make sure the negative battery cable is removed first before disconnecting the E.C.U. connector. If you do this test. Failure to do so can damage the E.C.U.

I guess thats where I would start if I were you. Good luck and welcome to the site

[Zrunner]

Well I really havent checked much at all because I am not really sure how. Im pretty good with actuall mechanical parts and things but i get lost with electronics. My trouble shooting is not worth anything. What you said makes scence but I just dont see how it can go out over a 3 day period like that. I will get a little volt meter thing and test away. I was lucky to find an fsm on the internet.

[sblake01]

I would also look at the cold start valve/thermotime switch combination. A leaking cold start valve or a bad thermotime switch could also make the car run rich.

[Zrunner]

o snap sorry i forgot to mention that all those sencors on the thermostate housing have been replaced. Sorry i keep forgetting to list everything that I have replaced. Thanks for the input though.

[sblake01]

And the cold start valve?

[DatsunZsRule]

"What you said makes scence but I just dont see how it can go out over a 3 day period like that."

Crazy things like that can happen sometimes. I'd still run the tests because by performing the tests at the 35 pin connector, you'll be able to rule out other components that are not the cause as well. Sure beats guessing and spending $$$ on things that are not the culprit.

"Im pretty good with actuall mechanical parts and things but i get lost with electronics. My trouble shooting is not worth anything."

Just take your time and follow the procedures in your FSM carefully and you should be ok

[Zrunner]

thanks for the help and encouragement. I have not had time to work on the car yet but yall are already far more helpful than the other guy

thanks

[DatsunZsRule]

No problem. let us know how it all turns out. Whos the "Other Guy"

[Zrunner]

cough...zcar.com...cough

Its not their fault. I would post and not get a reply. It happened more than a few times and i got fed up with it.

Zcar is still an awesome sight. You can still find all kinds of interesting stuff, just not the stuff i needed.

[DatsunZsRule]

Well honestly I'm not a fan of ZCAR.COM which is why I stopped going there a few years ago. Too many newer, yunger members would use the site as there own personal I.M. and would clutter the forums with B.S. or wrong answers to questions so God help anyone over there that tries to use there search feature for help I don't know, maybe it's gotten better there over time but my home is here at classiczcars.com