running rich

[Bob Marcho]

I just installed my rebuilt engine in my 1986 300ZX ITS car and took it out to the local dragstrip to check everything out. Warmed it most of the way, the first run was great, but on the return road I could not keep the engine running below about 2500 rpm. I staged again, but had to keep it running above 2500. Ran it through a 2nd time; it stumbled pretty bad off the line, and then she ran great after I got it up in the rpms.

Brought it home, started it up to unload off the trailer and everything ran fine. Drove it slowly around the block and as soon as it warmed up and the thermostat opened up I smelled gas. I looked out the rear window and black smoke is puffing out, it wouldn't run below 2500, which appears to me to signal running really rich.

I can rev it up and it runs great, but again it will barely idle until it goes above 2500 - 3000 rpm.

Any suggestions where to look?

Thanks,

Bob Marcho

[vwmann1]

I'm not a Z guy but it smacks of a bad coolant temp sensor.

[Bob Marcho]

I'm not a Z guy but it smacks of a bad coolant temp sensor.

Thanks for the heol. Not sure if it means anything, but the temp gauge works great.

Bob

[chuck baader]

Usually two sensors for the two functions, one for the ecu, the other for the gage. Could they be reversed? Also, check function of the tps and the O2 sensor. Good luck, Chuck