New to me, 280Z...

[Barefootdan]

So awesome! You can do a few things that are fairly easy. Take the valve cover off and make sure your valve lash is within spec. My car sat for a while before my rebuilt engine ran and I lost a rocker from a sticky valve. From there if everything is back in spec, you can switch your attention to your injectors and spark. Not sure if you drained your gas tank but there could be a possibility your injector clogged and it’s not firing. But you could also just smell your plug to see if it’s oil or gas 🙂 Spark is a quick and easy test. Start with the valve cover and lash and report back! 
 

edit: you can also do a compression test to check for your rings. I don’t suspect this is the issue but it’ll be another quick check!

Edited November 26, 2021 by Barefootdan

[dar5052]

Yeah I am going to start with the easy things like test for spark and bench test each injector. Good point on removing the valve cover to see if any slipped and check the lash. It looks like cylinder 6 is still firing because the end of the plug was dry, black... but dry. If I can get it running smooth again, I will probably dump kerosene into the cylinders to soften up the rings in the event they are stuck. That might help with the oil bypassing the piston. 

I really wanted to keep running this motor and do all the bodywork and then build a second motor after I have a clean running car. Worst case, I'll end up rebuilding this one while I do the body work. 

[Zed Head]

19 hours ago, dar5052 said:

I then started the car and the first time it started up just fine... however, the second time it started and shut back off. I restarted it and it was running really rough, like a bad misfire on a couple cylinders. I didn't have time left in the day to start diagnosing it but I took a look around and noticed oil around the spark plug on cylinder 6. I removed the plug, which was very loose, and could see evidence of oil on the threads and around the spark plug well. I suspect there is a valve stuck open or not fully seating or worse, the piston rings are shot or seized up.

Barefootdan's engine was in much worse shape than yours appears to be.  Don't get too far ahead in assuming major problems.

A loose spark plug can cause a miss, but stuck valves or shot piston rings cannot cause a loose spark plug.  Oll, gas, or moisture on the plug threads of a plug is not a surprise, the gases creep in to the threads and condense there.  Put a clean set of plugs in and give the engine a good tuneup before assuming terrible things.

The pictures show that a PO did some "hacking".  The PCV hoses are not correct, the crankcase is open to the atmosphere.  If the PO did not know about the hose under the intake manifold where the valve is the intake manifold might have a major leak.  76 has the fuel pump relay contact in the AFM and the AFM needs all of the air entering the engine to pass through it.  Low air flow can kill the fuel pump power.

[Barefootdan]

11 minutes ago, Zed Head said:

Barefootdan's engine was in much worse shape than yours appears to be.  Don't get too far ahead in assuming major problems.

Admittedly, I do jump to worst case scenarios too 😅 

[dar5052]

As of this morning, the car wouldn't start at all. It would just crank over. I decided to start with the easiest of tests... Didn't take long to find the culprit... I pulled the spark plugs out of 5 and 6 and tested both. The cylinder 6 spark plug was shot while 5 worked fine in both wires. I didn't bother checking the rest of them and just went and got a new set of plugs. As I removed the rest of the plugs, I could see that each plug was still wet with gasoline so I figured I was getting fuel in each cylinder. After changing all the plugs, it fired right up and now runs better than it did when I got it! 

@Zed Head I found the connection under the intake manifold. Is this what you are referring to? Where would a hose go to/from here? I guess that the valve cover connection should run to the tee connection to recirculate any gases from inside the head. I've seen some people just put a filter on it and let it vent to atmosphere. Not sure if that affects performance or not but certainly doesn't help the environment.... that said, my car hasn't run in so long that the smoke coming out of the tailpipe is nasty which I am sure is great for the environment. But hey, its a classic and I don't need to do emissions....😁

On a side note, I looked through the stack of receipts I have and confirmed that it is a ATK reman engine installed April 1990.

[Patcon]

These fuel injection systems like the system to be closed up. If the valve cover is vented to the atmosphere, the EFI shouldn't like that. If it does, it may have been "adjusted" to compensate for that. Air leaks tend to make the EFI run like garbage...

[Zed Head]

8 minutes ago, dar5052 said:

@Zed Head I found the connection under the intake manifold. Is this what you are referring to?

Yes, that is your PCV valve.  There is a port in the side of the block on that side that should have a hose that runs up to that valve.  The hole in the middle of the valve is letting unfiltered and unmetered air directly in to the intake manifold.

[dar5052]

@Zed Head got it! I guess that makes sense then if the valve cover hose is properly connected and the PCV valve is properly connected, it creates a balanced system through the motor. 

[Zed Head]

On 11/25/2021 at 3:40 PM, dar5052 said:

Any suggestions? The car ran beautifully last week when I put it in the garage

Don't get discouraged if it starts running poorly as you correct the PO's errors.  There are many tuning tips out there that people use to make things work again after they get wrong.  If it ran well once it will run well again.  It should be possible to have an engine that runs great AND does not smell like a cloud of gasoline vapors.

[dar5052]

@Zed HeadI agree, if it ran good once, it will run good again... but I guess that would have been my next question... what was the PO hiding by doing things the way he did? At this point it doesn't matter because I own the car... just curious to know what I might expect as I correct the "wrongs". I doubt the car was "adjusted" to run the way it is right now seeing as it was a work in progress that the PO gave up on. From what I was told, he just took the best motor he had and put it in the best body he had... made some suspension and brake improvements and the rest is up to me. 

[dar5052]

No turning back now! Finally moved my car off the rack and started disassembly.... This will be a laborious task since I'm bagging and tagging every part.

Found rot on both the front corners of the rocker panels behind the fenders. The driver side was repaired at some point long ago and did not hold up well. Are the front sections of the rocker panels sold separately or with the complete rocker? I checked zcardepot and they just have complete rockers.... and yes, I did shear off the two bolts holding the fender on... The driver side wasn't as bad..

[Patcon]

They're running a sale

https://kfvintagejdm.com/product-category/datsun/