I have owned my 1978 280z for about 20 years. It was the most reliable car I have ever owned. About a year ago it would just turn off while I was driving it.  I have replaced the following:

New stock pump pump

had the fuel tank drained-it wasn't bad

new fuel filter

new relays under the black metal cover in front of the battery

new relay behind the glove box (I can't remember the name of it)

New computer from Z man in Washington

I have ordered a new air control unit

After deciding what was wrong with it was beyond  me I took it to a local foreign car repair place in town. They got the car to run better by replacing the computer. They said they could tap the top of the old computer and the car would just die. The new one solved that issue. They drove it a couple of times and it would still act up occasionally.  I drove it for a week and it died and stranded me. I had it towed back to the shop, They worked on it cleaning some connections. I went and drove it home. Two weeks later I started it and it would not produce than than about 800 rpms. It will not accelerate at all and smokes a good bit. It acts like it is very rich.  I down loaded the 280Z Fuel injection bible. I have ordered new temperature probe and new plugs that are located where the top radiator hose attaches. 

I am getting sort of frustrated with it.  Any suggestions will be appreciated. Can anyone recommend a central Florida repair place with Z experience? I live in Vero Beach.

Thanks

Curt

What is the tachometer needle doing when it's smoking and running poorly?  Does it match what you hear from the engine?  800 RPM is pretty low.

Might be the ignition module going bad.  That will usually show signs on the tachometer needle.  Could also be the throttle valve switch (aka TPS).  Might be stuck on full throttle.  27% extra fuel.  Also could be running rich if the fuel pressure regulator diaphragm is cracked.  Remove the vacuum hose to the FPR and see if is wet inside.  It should be dry.

Page EF-15.

 

 

Edited January 15, 20232 yr by Zed Head
sings to signs

Thank you for your post, I appreciate your it. I will be back in town late this week. Where can I find a new ignition module? Is the module in the distributor? I will start it and see what the tach is doing and will message you back.

thanks

curt

The ignition module is by the fuse box.  They're expensive.  I found an eBay ad with a picture but I have no idea where these guys would get new modules.  Also don't know if the electronics still age when not used.

Don't get carried away.  Only posting this for the picture and for anyone else who might need one and want to take a gamble.  Seems too cheap to be true.

Put "NEW - OUT OF BOX Ignition Control Module For 1978 Datsun 280z 2.8L S30"  in the eBay search box.

https://www.ebay.com/

Interesting, That seller https://www.ebay.com/str/sparksurplus has over 110K items for sale, and over 2300 Datsun items that look pretty nice. Reasonably priced too. For all Datsuns.

I do not know the seller at all or purchased anything. Just an observation.  

I think I have one of those ICM's too. Just not sure of the car it is from. 

The 75-77 models have a screw panel for the connections.  78 is the only one with the plug connector.   I think that all of the plug connector Z ignition modules are the same.  The eBay price is stiff competition though, compared to what they used to go for.

The picture looks right.  Wonder where the warehouse of old new ignition modules was, that these Spark people found.

19 hours ago, Zed Head said:

The ignition module is by the fuse box.  They're expensive.  I found an eBay ad with a picture but I have no idea where these guys would get new modules.  Also don't know if the electronics still age when not used.

Don't get carried away.  Only posting this for the picture and for anyone else who might need one and want to take a gamble.  Seems too cheap to be true.

Put "NEW - OUT OF BOX Ignition Control Module For 1978 Datsun 280z 2.8L S30"  in the eBay search box.

https://www.ebay.com/

I got home last night. This morning I started my car. It ran much better I am not sure why though. The tach would slowly fluctuate between 750-900 RPM. It would also freely rev like it should.  Also it was not smoking. Go figure. The next time I go to start it will act up. I have an intermittent issue somewhere. I did unplug the fuel pressure regulator and it appeared to be dry. I bought the ignition control module on ebay.  Thank you again for your help.

Curt

Your cold start valve vould be flooding it with fuel after it warms up. You can unplug it to see. You can also unplug the auxiliary air regulator. Another cold start device. Easy things to check off your list of possible problems.

Over the past few years I've purchased a couple things from Spark Surplus and can attest for their legitimacy. I'm not sure where their "surplus" comes from, but they are a legit entity. Don't always know any details about what they have, but with that many auctions, who would?

Thanks- I ordered the ignition module from them. Hopefully will fix it or maybe some part of the issue.

On 1/17/2023 at 6:48 PM, Zed Head said:

The ignition module is by the fuse box.  They're expensive.  I found an eBay ad with a picture but I have no idea where these guys would get new modules.  Also don't know if the electronics still age when not used.

Don't get carried away.  Only posting this for the picture and for anyone else who might need one and want to take a gamble.  Seems too cheap to be true.

Put "NEW - OUT OF BOX Ignition Control Module For 1978 Datsun 280z 2.8L S30"  in the eBay search box.

https://www.ebay.com/

I started it again today and it ran well. No smoke and it revs nicely. It idles at 750 to 825 or so rhythmically. Starts very easily. I will change out the ignition module  and report the results. Electrical intermittent problems drive me crazy. Should I remove the fuel pressure regulator to check if it is leaking? I pulled the hose off on top and it looked dry-really hard to tell if it is leaking by looking in the hole.

23 hours ago, siteunseen said:

Your cold start valve vould be flooding it with fuel after it warms up. You can unplug it to see. You can also unplug the auxiliary air regulator. Another cold start device. Easy things to check off your list of possible problems.

I unplugged the cold start valve and it made no difference-I live in Florida so I don't think it is ever needed hear. Where is the auxiliary air regulator? Thanks for your post!

After reading more it sounds like you're onto something electrical related? I was just thinking of some easy things to check first. Here's the AAR plug-in and one of the best helps I've gotten for my '77 280. Good reading with lots of photos. Hope you get it figured out soon.

http://atlanticz.ca/zclub/techtips/aar/index.html

http://atlanticz.ca/zclub/techtips/EFI&fuel.htm

http://atlanticz.ca/zclub/techtips/

21 hours ago, furypilot said:

It idles at 750 to 825 or so rhythmically.

Is this the current problem?

Or is it still doing this?  Can you summarize what you're trying to fix now?

On 1/15/2023 at 12:55 PM, furypilot said:

About a year ago it would just turn off while I was driving it.