L28 280Z Car engine problems!!!

[Jdizz07]

Hi all, 
I have recently bought a 280Z 1978 in London UK. It was an ex Cali car and from the license plate hadnt been driven since 2007. Ive spent the last couple months trying to get her to run right, however She went from initially running a bit rich/smokey to now not running at all. 

Ive replaced the fuel pump as the old one was dying on acceleration (Installed a fuel pressure gauge). Ive replaced all normal things, spark plugs, oil, etc. The loom was very corroded so I have replaced the injector plugs with new ones, making sure to keep the right wire numbers/code from the handbook illustration.

The AFM has been siliconed shut as in it has been perhaps tinkered with before. However I have diagnostic tested it and all readings read are that of factory. All readings from the ECU are fine. 
I have a vacuum leak somewhere, as is sometimes runs when all the hoses are off, if i go to reconnect say the breather hose back on to the rocker cover it just dies. Im stumped on that one.

Starting to get really frustrated and have even thought of ripping out the F.I and chucking in some old carbs off a 240 or even still, breaking the bank and going with triple webers! Obviously this is not the desired outcome I just want the bloody thing to go!

Any help would be great as like everyone here, I want to enjoy her, especially now that summer is here!

Thanks
JD

[Dave WM]

if it runs with the breather disconnected then you must be running super rich. Have you gone thru the EFI check list esp regarding the temp sensor for the EFI, and have you confirmed the cold start injector is working properly. No need to rip out the EFI, it works VERY well, you just need to systematically check the parts of correct operation.

[Zed Head]

You haven't provided any numbers so it might be that you're just using continuity as your test indicator.  You can get fooled on the coolant temperature sensor (CTS) if its connector is attached to the thermotime switch.  Make sure that the CTS is correctly connected.  Get an actual resistance reading at the ECU and compare it to the temperature chart in the FSM,or the Fuel Injection book.

Since the black cover on the AFM is already gooped up with silicone you might as well pop it off and watch the big weight move while the engine runs.  Make sure it's moving freely.  They've been known to get stuck, showing more air to the ECU than actual.

Make sure that your idle setting is high enough to keep the engine running when things are right.  Maybe it's set too low and the engine needs the extra air from a loose hose or two.  Just thinking outside the box.  At least it runs so that you can mess with it.

[Jdizz07]

Thanks for the replies guys.

Ill will get around to it this weekend checking again over the sensors and readings. One quick one if you think its super rich, When I replaced the fuel pump I did away with the pressure regulator?? that is connected very close to the fuel pump. See photo attached. I assumed that my new 32PSI fuel pump matched that of factory so wouldnt need it. Do I need to put back in this factory part? Could that be some of my problem?  

Thanks in advance.

[Dave WM]

pretty sure the factory pump is rated at 55psi, most aftermarket pumps are 90psi. I went factory since you can still get them. I pretty much use that logic on all parts (if factory is available use that). That being said the fuel damper was part of the orig design so I see no reason to assume its ok to delete it. Maybe it will be fine but you just keep adding variable when deleting or re engineering stuff. The stock setup works very well, that includes all the EFI, EGR and PCV systems. You need to get a fuel pressure gauge hooked up and then go thru the entire EFI section of the FSM in a methodical way. Things not generally covered in the FSM directly will be rust in the tank and the fuel lines. It does cover it indirectly by spec of the PSI and volume of fuel that is being pumped. Old school diagnostics start with a check of the plugs, how do they look? you can get a lot of insight into the condition of an engine by checking there. Also a good cylinder compression check is one of the 1st things to go to for overall health of an engine. But again all this is covered in the FSM,

[Jdizz07]

I read on the forum that factory at idle was 36PSI (apologies not 32), and I bought a fuel pump that ran at 3 Bar pressure to match. My gauge in line reads that correct. Anyway I'll have a tinker this weekend and get back. Shes slowly gone from running, to running poorly, to sometimes running poorly, to now, not even running over the course of a couple weeks and me not touching it. Frustrating!!! I used to own a 280ZX that was so reliable and always started and ran like a dream, so Im definitely reluctant to go for carbs.

Thanks again

[Dave WM]

the fuel pressure is maintained by having a pressure regulator that monitors the engine vacuum to maintain a constant pressure relative to that. 36psi is where it should be with the pump running but the engine NOT running (no vacuum in the intake manifold). at idle you are more likely to see 30psi assuming all things are working as they should. The pressure will rise and fall based on engine vacuum. A massive air leak would therefore effect not only unmetered air but the fuel pressure regulator as well. You may want to get a vacuum gage hooked up as well. Vacuum leaks can create havoc. check all hoses and don't forget the PCV hose on the crank case AND the PCV valve. This assume you have a vacuum leak issue of course.

the excess fuel provided by the pump will be returned to the tank via the return line. I suppose you will be ok with a non standard pump but again you are introducing a variable into the system. Its hard to know how to proceed unless you start by baseline the pump (pressure and volume AT the fuel rail). I started with a factory pump just to be sure I did not have an issue. What was in the car was one of the high pressure skinny long pumps that was good for 90psi.

Are there any other non stock modification to the various systems (PCV as an example). things like loose fitting valve covers including the oil cap, can cause air leaks, as can leaky injector o rings, even a non secured oil dip stick. Also all the hoses that flow air from the AFM to the throttle body should be inspected for crack that would allow air to go unmetered.

 

 

Edited July 19, 2017 by Dave WM

[siteunseen]

Mine would run at first after it has sat for awhile, then the crudded up tank would slosh around and clog up my fuel filters slowly killing the car.  Ended up dropping the tank and refurbishing it.

Here's a quick and cheap way to see if you have trash in the tank and/or prevent it from getting in the EFI system.

http://atlanticz.ca/zclub/techtips/fuel/g3filter/index.htm

Edited July 19, 2017 by siteunseen

[Zed Head]

44 minutes ago, Jdizz07 said:

 Shes slowly gone from running, to running poorly, to sometimes running poorly, to now, not even running over the course of a couple weeks and me not touching it.

That's a pretty good clue.  Plus the fact that it runs better with vacuum leaks.  The fact that it slowly got worse is odd.  But it definitely sounds like too much fuel.  So that could be injectors staying open too long (ECU controlled) or the CSV leaking (easy to check), to the AFM sticking (also easy to check).  

Could be that somebody tuned the engine to run with vacuum leaks and when you remove them it runs poorly.  Can you crank up the idle speed so that it stays running? That will allow you to examine the parts that could have been "tuned" to incorrectness.  I would pop that AFM cover off first thing.  Make sure that the AFM vane is moving.  Its position has a direct impact on injector open time.  It's not uncommon for them to get stuck.

[Zed Head]

He has a fuel pressure gauge inline apparently.  So that should tell if there's a clog.  Just saying, he's already head of the game, with the gauge.  

This just reminded me of the other big sneaky thing that gets people - the fuel pressure regulator (FPR) might have a hole in the diaphragm.  Pull the vacuum line off of the FPR and check it for fuel.  It kind of fits the symptom, with a small hole getting bigger.  The diaphragms get brittle with age.  I have an old one that cracked in to pieces when I took it apart.

[Jdizz07]

Hey guys, managed to get a couple hours in after work tonight, and good news... Shes running. Pretty rough mind you, but I turned up the Idle, and both the cold start valve (21, 47) and thermotime wires (45, 46) were around the wrong way... My fault entirely from replacing the corroded and brittle clips back when I got it months ago. I have attached a photo of the engine bay, anything look unusual??? 

Trying to up load a video so you can see how rich shes running... pardon the boxes of Stella Artois, its me birthday on Saturday hahaha

Again, vacuum hoses off and running better. Unsure...

Thanks again guys. Feel back in love with it tonight!!!

Cheers JD

IMG_6761.MOV

[Zed Head]

Sounds like it's running on five cylinders.  You can remove the injector plugs one at a time to find the cylinder that's not firing.

Your video is all choppy and hard to watch.  Might be my computer or maybe the recording.  You might start a youtube account and put it there.  Took a long time to download 74 MB.

Take the vacuum hose off of the FPR, red arrow, and see if there's raw fuel inside the hose.

Edited July 20, 2017 by Zed Head