78' 280z running rich

[Zed Head]

14 minutes ago, Pochie45566 said:

 I have a working afm with the factory setting mark and when I set it to that it just runs even more rich. 

 And this was not an all of a sudden issue, it’s always run pretty rich. 

Is it a Nissan factory original AFM or Fuel Injection Corporation reman?

[Pochie45566]

3 minutes ago, Dave WM said:

Well what I did, and this may not apply to you, try unplugging the water temp sending unit, yes this SHOULD send the mix super rich, for me it made the car run better but was still fouling the plugs.

If for some reason unplugging the sensor does not result in near instant super rich (and engine dies), then there maybe something else going on, causing the fouling not related to the mix.

 

It runs well now, just smells like gas and gets horrible mileage but I will try unplugging the sensor and seeing what happens. 

Should I set my AFM back to stock? 

3 minutes ago, Dave WM said:

also I have to ask, I presume the air filter is in good shape.

Yes the filter is in good shape. 

1 minute ago, Zed Head said:

Is it a Nissan factory original AFM or Fuel Injection Corporation reman?

Pretty sure is Nissan factory. Could be from a different car though. I have no idea. Any way to check? 

[Dave WM]

so it did not used to not smell like gas and got better gas mileage? did you put in fresh plugs drive it around the block and then pull them and they are black? part of the problem maybe making assumptions with out actually seeing what you are describing.

 

Edited May 11, 2019 by Dave WM

[Zed Head]

3 minutes ago, Pochie45566 said:

It runs well now, just smells like gas and gets horrible mileage but I will try unplugging the sensor and seeing what happens. 

Should I set my AFM back to stock? 

Pretty sure is Nissan factory. Could be from a different car though. I have no idea. Any way to check? 

What is mpg, in numbers?

Yes.

There should be a green label on it with numbers and letters, like A31-.....  They're all very similar though.

https://www.thezstore.com/page/TZS/PROD/11-3040

[Dave WM]

The problem with the AFM is its not likely to every require any adjustments, there is nothing to get out of adjustment. It can wear on the carbon tracks but I doubt that ever is really an issue.

It is often the thing that gets adjusted when ever there is a problem with the EFI. So Yes I would put it back to the original spot it was at when the car was running well, then look for another problem that would happen suddenly. I am assuming this problem happened "suddenly".

[Pochie45566]

4 minutes ago, Dave WM said:

so it did not used to not smell like gas and got better gas mileage? did you put in fresh plugs drive it around the block and then pull them and they are black? part of the problem maybe making assumptions with out actually seeing what you are describing.

 

It had always smelled like gas, got bad mileage, and leaves black spots on my driveway. I did put fresh plugs in then go drive and they were black. 

Im just simply more motivated to fix this issue now that the nice weather is out and my garage isn’t freezing?

This is not a sudden problem, I’m sorry I described it to be that way. 

Zedhead, I’m getting around 11-15 MPG 

Edited May 11, 2019 by Pochie45566

[Dave WM]

Gas smell could be leaking fuel lines, leaking injectors, leaks at the pump and tank connections, On a car this old you must replace ALL lines and check for leaks after done. Also ALWAYS carry a fire extinguisher with you and have it ready to use. Make sure you use FI hose after the pump. Ok to use regular fuel line on the returns.

Gas smell or exhaust smell both are bad, but if exhaust a common problem as seals and grommets dry up and allow fumes into the cabin.

Gas mileage will very, lead foot 14mpg hypermilager 24mpg city vs highway also matter. lead foot city driving 14mpg or worse.

where are the black spots? are they deposits from the exhaust?

What are the plugs you are using?

The confusion on this being a recent problem was from the word "lately" in the opening of the thread.

If its been a problem from the beginning the diagnostics have to include the possibility that something is just installed incorrectly or has been modified, much harder to diagnose (as in my ign problem).

 

Edited May 11, 2019 by Dave WM

[Pochie45566]

3 minutes ago, Dave WM said:

Gas smell could be leaking fuel lines, leaking injectors, leaks at the pump and tank connections, On a car this old you must replace ALL lines and check for leaks after done. Also ALWAYS carry a fire extinguisher with you and have it ready to use.

Gas smell or exhaust smell both are bad, but if exhaust a common problem as seals and grommets dry up and allow fumes into the cabin.

Gas mileage will very, lead foot 14mpg hypermilager 24mpg

where are the black spots? are they deposits from the exhaust?

What are the plugs you are using?

The confusion on this being a recent problem was from the word "lately" in the opening of the thread.

If its been a problem from the beginning the diagnostics have to include the possibility that something is just installed incorrectly or has been modified, much harder to diagnose (as in my ign problem).

 

Previous owner did new fuel lines and new injectors, and I don’t have any reason to believe there are any leaks. But I do always keep a fire extinguisher in the back haha. 

The black spots are just behind the exhaust pipe tips. I am using ngk r plugs. 

Also on WOT sometimes black smoke comes out the exhaust. 

I appreciate your help, I’m just a bit confused on what steps to take next. 

[Zed Head]

I had a similar problem with my car right after I bought it.  It was the FPR, it seemed to stop regulating when it got hot.  It was a hard problem to diagnose, I only measured pressure when the engine was cool.  I replaced it with an adjustable FPR, set pressure to spec., and it ran fine.

Just a possibility.  Another one, that happens but is uncommon, is the ECU.  They tend to run rich as they go bad.

If you have spare parts, swapping and checking is an option.

[Dave WM]

what color are the injectors?

have you verified the operation of the TVS

You did say you checked all the resistance readings AT the 36 pin connector correct?

again what are the MPG numbers, and what are the Sparkplugs you are running?

Edited May 11, 2019 by Dave WM

[Pochie45566]

3 minutes ago, Dave WM said:

what color are the injectors?

have you verified the operation of the TVS

You did say you checked all the resistance readings AT the 36 pin connector correct?

again what are the MPG numbers, and what are the Sparkplugs you are running?

The injectors? When pulled they have no buildup. They have a green ring around the outside. Not sure that you are looking for there. 

What is TVS? I have checked the TPS. I checked every component check in the EFI bible related to running rich. They all appear fine. 

I get 11-15 MPG and am running NGK r plugs 

[Dave WM]

Does the engine have a mis fire?

you could try a power balance test