4 hours ago, kcpope said:

Remove all injectors and clean them by actuating them them with a power supply while pressuring them with carb cleaner.

That's a good idea BUT: Watch that you do use a power supply with a current set to low because they will burnout if you put 12V directly on them.

How low the current should be i don't know.. i always use a small 9 volt battery to see if they click! A 9V battery has not the current to damage the injector!

You could also use a resistor that normally sits in series with the injectors in the car.. see elec. diagrams.

Since you are going for smog test I'd really concentrate on the different coolant temp sensors that calculate the air/fuel ratio. They are in the thermostat housing. There's the thermotine sensor and a coolant sensor you could remove, very carefully-they are precious little things with their old plastic connectors, and clean the brass on them as well as the threads. Don't use teflon tape on those threads, it effects the grounding I've read. You'll be better off draining the antifreeze before you pull them but you probably want to put new in anyway. The 4 wires that connect them also shown as "bullet connectors" should be really clean too. These will make one run rich with low readings when they are "dirty" or corroded.

If you don't have one, an auto parts store might lend one out, but air leaks are another thing that will cause the fuel mixture to be off so checking all the old rubber hoses for cracks is a big help with a vacuum gauge. The accordion rubber connecting the AFM to the throttle body is prone to cracks when people remove and reinstall them. If you get one off clean the throttle blade and the actual body or area where it closes with a toothbrush and I use lacquer thinner on aluminum. The blade gets gummy after all these years and won't seal off like it should letting more air get through.

Your motor needs to be sealed up tight after the AFM.

Unmeasured Air: Any crack or loose clamp between the MAF sensor and the intake manifold will introduce unmetered "unmeasured air" into the system. This confuses the ECU, resulting in a lean air-fuel mixture, rough idling, and engine hesitation.

I'm not sure if you have the whole atlanticz tech tips so here it is just in case. Electrical and EFI and Fuel are two of the best.

https://atlanticz.ca/zclub/techtips/

Edited June 2Jun 2 by siteunseen

If you are in California, get a pre-test if that's still available. You don't want the car tagged as a gross polluter.

Bureau of Automotive Repair

Smog Check: When you need one and what's required

Smog Checks help keep California's air clean and your vehicle running smoothly. Regular inspections check that your vehicle meets emissions standards. They also identify needed emissions repairs, help

You may have read about it in another thread as far as a good test for having a vacuum leak. A good test is while it’s idling, begin to unscrew the oil filler cap. If it starts to stumble a bit that’s a good sign of not having any leaks. @Dave WM passed that on while I was reviving my 78.

12 hours ago, siteunseen said:

Since you are going for smog test I'd really concentrate on the different coolant temp sensors that calculate the air/fuel ratio. They are in the thermostat housing. There's the thermotine sensor and a coolant sensor you could remove, very carefully-they are precious little things with their old plastic connectors, and clean the brass on them as well as the threads. Don't use teflon tape on those threads, it effects the grounding I've read. You'll be better off draining the antifreeze before you pull them but you probably want to put new in anyway. The 4 wires that connect them also shown as "bullet connectors" should be really clean too. These will make one run rich with low readings when they are "dirty" or corroded.

If you don't have one, an auto parts store might lend one out, but air leaks are another thing that will cause the fuel mixture to be off so checking all the old rubber hoses for cracks is a big help with a vacuum gauge. The accordion rubber connecting the AFM to the throttle body is prone to cracks when people remove and reinstall them. If you get one off clean the throttle blade and the actual body or area where it closes with a toothbrush and I use lacquer thinner on aluminum. The blade gets gummy after all these years and won't seal off like it should letting more air get through.

Your motor needs to be sealed up tight after the AFM.

Unmeasured Air: Any crack or loose clamp between the MAF sensor and the intake manifold will introduce unmetered "unmeasured air" into the system. This confuses the ECU, resulting in a lean air-fuel mixture, rough idling, and engine hesitation.

I'm not sure if you have the whole atlanticz tech tips so here it is just in case. Electrical and EFI and Fuel are two of the best.

https://atlanticz.ca/zclub/techtips/

Great info there, thank you. I'll add cleaning the coolant temp sensors and throttle body to my list.

And yes, I can already confirm that I have a crack in my accordion rubber intake tube DOWNSTREAM of the AFM. That will have to be fixed.

@SteveJ Good idea, will do. According to the cars history, it's last smog check was in 2008 and it failed and was tagged as a gross polluter, as you said. And in CA, that means you can't register it. No activity after that, which is probably why it was parked. With everything I'm "tuning up", hopefully we address whatever that 2008 failure point was.
@Yarb Good tip, I'll do that when the time comes.

Edited June 2Jun 2 by kcpope

Just documenting my progress as I go along. Today I drained the tank and disconnected any rubber lines to the hardlines both at the tank and under the hood. Going to fill the hardlines with acetone and let them sit for a couple hours.

A couple observations:

Someone used a non fuel rated hose at the fuel pump so that will need to be fixed

5 injectors appear factory, A46-000001. One aftermarket injector on cylinder 6. Interesting.

Pulled all the plugs, and they all look about the same as the one in the pic.

Check your distributor breaker plate. They tend to get rusted and stop advancing timing under vacuum. That will affect emissions. Might be able to break it free with some lubrication, but don't force it. The plastic bearing retainer tends to break. Disconnect the vacuum canister rod and move it by hand. Or remove the retaining screw for the canister and move the canister back and forth. Sometimes the diaphragm in the canister cracks and vacuum no longer moves it. Be gentle.

I checked Rockauto for Champion plugs and that number does not show. Closest is RN11. There sure are a lot more plug types spec'ed these days than I remember. I think that manufacturers might just be saying "close enough" to make some sales.

Nickels and dimes...

https://www.rockauto.com/en/moreinfo.php?pk=205531&cc=1209260&pt=7212

https://www.rockauto.com/en/catalog/nissan,1978,280z,2.8l+l6,1209260,ignition,spark+plug,7212

@Zed Head Breaker plate, that's the word I was looking for! That's the piece I remember from my previous dizzy rebuild. It has the little ball bearings in it, yes. I'll add a dizzy inspection and potential rebuild to my list, thanks. And I'll plan on just replacing the plugs with the proper NGKs. No sense in keeping these plugs if they're only "close enough".

Edited June 3Jun 3 by kcpope

Something I thought about is the Cold Start Valve, small injector type thing that shoots some fuel on start up. Is there a way to disconnect for his Smog test without getting called out for it? Maybe unplug it but appear to be plugged up? The reason I say this is it's a potential "rich fuel/air" reading for the test if it isn't working right. I know nothing about smog test other than what you guys write about on here. So there's that.

I found this from Andrew at MSA.

The cols start valve is located right on top of the standard 280z throttle body in the middle of the housing. It's held in by 2 bolts, has a fuel line attached to it and a 2 prong electrical connector. It is essentially an extra fuel injector that adds extra fuel to the intake system of the fuel to help it run while cold, so it get's to operating temperature quicker. It is controlled by the Thermo Time switch in the Thermostat housing and relies on the Water temp sensor and switch in the thermostat housing to be operating properly and accurately as well.

15 hours ago, siteunseen said:

Something I thought about is the Cold Start Valve, small injector type thing that shoots some fuel on start up. Is there a way to disconnect for his Smog test without getting called out for it? Maybe unplug it but appear to be plugged up? The reason I say this is it's a potential "rich fuel/air" reading for the test if it isn't working right. I know nothing about smog test other than what you guys write about on here. So there's that.

I found this from Andrew at MSA.

The cols start valve is located right on top of the standard 280z throttle body in the middle of the housing. It's held in by 2 bolts, has a fuel line attached to it and a 2 prong electrical connector. It is essentially an extra fuel injector that adds extra fuel to the intake system of the fuel to help it run while cold, so it get's to operating temperature quicker. It is controlled by the Thermo Time switch in the Thermostat housing and relies on the Water temp sensor and switch in the thermostat housing to be operating properly and accurately as well.

It's a good thought, but I don't think that will hinder my smog results. Before the test even begins, the car is left to idle for several minutes to get up to operating temp. So I'm thinking that cold-start injector should be well past OFF at that point. I've had smog techs tell me in the past to drive the car on the freeway beforehand and to get it nice and hot. Apparently that can help achieve better results🤷‍♂️

5 minutes ago, kcpope said:

It's a good thought, but I don't think that will hinder my smog results. Before the test even begins, the car is left to idle for several minutes to get up to operating temp. So I'm thinking that cold-start injector should be well past OFF at that point. I've had smog techs tell me in the past to drive the car on the freeway beforehand and to get it nice and hot. Apparently that can help achieve better results🤷‍♂️

Fresh oil, too.

Little progress update.

Drained all the varnished gas from the tank, and then dropped the entire tank.

• Lots of old dry varnished gas flakes in the tank. Safe to say gas doesn't dissolve these chunks. You can see them on my tailgate in the first pic. It's not rust (non-magnetic), just old gas I suppose. Smells like death too.

• Used a gallon of lacquer thinner to first dissolve the varnish in the tank, then followed that with a 1:4 solution of muriatic acid and water. Dropped about 50 quarter sized washers in there too for some mechanical scrubbing action.

• Results speak for themselves. Kind of a pain in the butt, messy process, but it does work. Probably could've spent more time and got it perfect, but even this took me 2 days. Still a 95% improvement.

• I'm glad I dropped the tank and flushed out all the lines. My return fuel line in the tank was definitely restricted and gummed up. It was flowing maybe at 20% of what it should be. So that's one culprit checked off the list of things that could cause poor engine performance.

• Also couldn't resist removing the rear bumper and shocks while I had the tank dropped.🙂

• Couple before and after pics attached.

Next up is the fuel pump assembly and sending unit...

Edited June 17Jun 17 by kcpope