280Z Difficulty starting

[Chickenman]

Rock Auto has AC Delco ( good brand ) re-manufactured gear reduction starters for $57.99 exchange. If you want o keep your old core for a spare you pay an extra $18.00. Limited Lifetime Warranty as well.

 

AC Delco 3361349: https://www.rockauto.com/catalog/moreinfo.php?pk=999727&cc=1209260&jnid=537&jpid=1

 

The gear reduction starters are the Cat's meow...

Edited August 21, 2015 by Chickenman

[Chickenman]

I can't remember if any one has mentioned this, but it is possible to mix up the connections to the ThermoTime switch and the ECU Coolant temperature switch. Maybe double check your connections. The Thermo Time wires are green in color and the ECU CTS wires are black in clor.

 

And yes the engine will start and run. Crappy at first, but then surprisingly well when it is fully warmed up. Guess how I know?  BTW... you may have to peel the electrical tape back to see the true colors of the wires. Old dark green wires look almost like Black wires!!

 

Edited August 21, 2015 by Chickenman

[Captain Obvious]

The thermotime can only fire the CSV when the key is in the START position. Repeatedly turning the key from ACC to ON doesn't send any power to the thermotime or CSV. You will not flood the engine by doing that. The only time the CSV can possibly get power to open is when the key is in the START position. And there is no functional link between the ECU and the CSV. The ECU does not cause the CSV to fire, nor does it even know that it ever happens. Completely independent.

 

You're looking for the fuel pump relay? This is a 77, right? If that's the case, it's the "two relays in one case" that lives above the driver's left knee. 78 is out in the engine compartment in front of the battery, but 77 is not. But I don't think this is a fuel pressure problem. Sure, the pressure drops off when the car is not in use, but it behaves pretty much the same way whether it's been primed or not. It sounds like it holds pressure for at least a couple minutes... Something to look into in the future but I don't think it's the hot iron at this time.

 

And about a clear flood mode? I've never seen any documentation to support that belief. I guess they could have a special mode where it could cut off the injectors completely if the frequency of the ignition pulses are "cranking engine" slow and the WOT contacts in the TPS are closed. But as I said, I've never seen any mention of that anywhere.

 

Chickenman, What is it that makes you think your 76 has that feature?

 

[Zed Head]

He said it's a 1978 model.  Post #1.  May have changed later but I didn't run through all of the pages.

 

Fuel pressure is a funny thing.  If your lines and filter and parts in between the pump and FPR are stiff, it will drop rapidly.  If they're flexible and can store pressure, it can live on for a while.

 

Considering all of the potential causes that seemed reasonable but weren't the cause, I'm in process-of-elimination mode.  If the pump is fully powered while the key is turned to Start and it still has starting problems, then move on from all fuel pressure-related cusses.  If a surprise happens and the engine starts up every time, then we'll come up with ten new reasons that fuel pressure would drop during starting.

 

Since I have a nice multimeter and like to use it I'd probably be measuring various things to make sure the ignition system is strong and providing good spark.  I think that I mentioned my weak ignition module theory way back in a previous page, along with various descriptions of how low voltage causes weak spark.  I probably would have wired in a GM HEI module by now, because I like redundancy anyway (that's how I ended up with one on my car now).  

 

But, only one thing can be done at a time.  So, a paper clip in the pump relay is simple and quick, therefore - why not?

[Marios280Z]

Thanks guys for all the analysis and advises.

I can't remember if any one has mentioned this, but it is possible to mix up the connections to the ThermoTime switch and the ECU Coolant temperature switch. Maybe double check your connections. The Thermo Time wires are green in color and the ECU CTS wires are black in clor.

 Chickenman, I have verified my thermotime switch and WTS wires, but  Iwill revisit the path between WTS and the ECU. This morning when I disconnected WTS after first unsuccessful attempt at cranking, the car started right up but almost immediately started to run like crap. I turned the car off,I reconnected the WTS and started the car no problem. I wrote about it few posts earlier and Zed Head commented on it.

 

 

 

I've played with FPR in one of my videos, and form all I have read it is operating correctly.  I also tried to clamp the fuel return line form FPR to see if that would stop the leak, but it didn't. My battery voltage seems to be right on spot. Thanks a lot for the link to Rockauto. I may just order that when I come back from vacation.

Question about starter. Is it the same unit in early 240Z as it is in my late 280? I may have access to a 240 parts car.

 

 

He said it's a 1978 model.  Post #1.  May have changed later but I didn't run through all of the pages.

 

Fuel pressure is a funny thing.  If your lines and filter and parts in between the pump and FPR are stiff, it will drop rapidly.  If they're flexible and can store pressure, it can live on for a while.

 

Considering all of the potential causes that seemed reasonable but weren't the cause, I'm in process-of-elimination mode.  If the pump is fully powered while the key is turned to Start and it still has starting problems, then move on from all fuel pressure-related cusses.  If a surprise happens and the engine starts up every time, then we'll come up with ten new reasons that fuel pressure would drop during starting.

It is 78. In one of my posts where I included a video I have filmed the entire process of me priming the fuel pressure and then starting process. I just watched the video on you tube again, I just don't recall which post # it is. Since I'm filming my fuel pressure gauge the video clearly shows that during cranking my pressure actually goes up a bit, so the pump is providing sufficient pressure. You can also see and hear how that started acts funky and does this strange buzz just as the engine tries to catch, and then it stumbles. I have also heard the fuel pump run many times when I had the starter disconnected and turn the key to START.

 

 

 

 

Since I have a nice multimeter and like to use it I'd probably be measuring various things to make sure the ignition system is strong and providing good spark.  I think that I mentioned my weak ignition module theory way back in a previous page, along with various descriptions of how low voltage causes weak spark.  I probably would have wired in a GM HEI module by now, because I like redundancy anyway (that's how I ended up with one on my car now).  

That ignition module thing...Where the hell is it? Sorry..still learning...   You are not talking about the ignition coil, are you? There is this little black box next to the ignition coil, but when I opened it up all it had was two wires on each side connected by nuts. Is that it? I cleaned them up when I was on the task of cleaning ground connections in the engine bay.

 

OK guys,time to go to bed . Long trip ahead of me tomorrow. I will be off the grid for few days, so  I will talk to you when I get back.

 

[Captain Obvious]

Zed, Thanks for the reminder. Yes, it's a 78. (Hence all the discussion about the transient state theory to the fuel pump relays and the whole priming thing.) I should know better than to get involved in more than one thing at a time.

 

78 was also the year they started with the gear reduction starter, right? I've never messed with one of the later starters, but is it possible that the noise you guys are talking about with the starter may be related to that?

 

Mario, I don't think it's an ignition issue, but your module is on the kick panel wall next to the passenger's right foot. Have a good time on vacation and we'll catch up when you get back.

[Chickenman]

(Snip)

And about a clear flood mode? I've never seen any documentation to support that belief. I guess they could have a special mode where it could cut off the injectors completely if the frequency of the ignition pulses are "cranking engine" slow and the WOT contacts in the TPS are closed. But as I said, I've never seen any mention of that anywhere.

 

Chickenman, What is it that makes you think your 76 has that feature?

 

Technical Service Bulletins from Nissan. We had a lot of flooding problems in Canada ( Cold climate ) on the earlier cars. Combination of weak Trignition units in the 75 and 76 models and Thermal Time Switches going out of spec. Later Canadian models got a revised TTS with a shorter " Duty Cycle ".  8 seconds vs 12 seconds.

 

Clear flood procedure was documented in TSB  as:  Hold throttle pedal to floor while cranking. ECU senses WOT from TPS and cranking signal and reduces injector time by 50%. All model years had this feature built in. FSM just doesn't mention it. TSB's do.

 

Actually, I've never heard of any electronic FI system NOT having a " Clear Flooding " program. It's very simple to implement and it would be a serious oversight in design. And the Bosch engineers were very good at engineering, even on these early Analog creations.

Edited August 21, 2015 by Chickenman

[Zed Head]

I have Vol. 231 TSB for the 1976 280Z, and the collected TSB's, January - December 1979 for all Nissans, and can't find any reference to it.  Can you post a copy?  Memories are fallible, that's what paper (now computers) is/are for.

 

I'm surprised that something so common and easily perfumed by a customer isn't documented in any of the FSM's or Owner's Manuals.  Just seems strange.  Any factory-published reference to it would be good to see.

[Captain Obvious]

If there is truly a clear flood mode to the ECU It seems really odd that there would be no mention of it in any of the service manuals, owner's manuals, or the the FI guide. The ECU has access to the START signal and the WOT signal, so they COULD have put something like that in there. But if they did put that in, why didn't they tell anyone about it?

 

Yeah, if you could post a copy of that TSB, that would be a great piece of FI trivia!

[Captain Obvious]

Mario,

 

I know you're on vacation, but if I don't write this stuff down, I'll forget. Two things to look into when you get a chance...

 

1) Not sure if you still have an EGR valve (or if has been removed). If you do still have one, it might be leaking when it should be closed. This would lean out your idle mixture. Actually it would lean out your mixture at all times, but like any other fixed size vacuum leak, it would have the greatest impact at low RPMs.

 

2) Have you verified that your ECU is getting the START signal? Pin 4 should go hot in START and that temporarily richens up the mixture some.

[Chickenman]

I'll have to talk with one of the Old Nissan Parts guru's to see if he still has copies of all the  early Service TSB's. Unfortunately I threw out all of my old Nissan Parts and Service Training literature about 2 years ago while spring cleaning.  A few months later I ended up buying the 280Z. Go figure...

 

One thing I'm glad I did keep is most of my Certificates that I received from Nissan in the 1980's and 90's. It was an important time in my life and I've recently started re-connecting with my Nissan roots after being away for over 20 years.

[Marios280Z]

It's been few weeks since I looked into my starting issue (family vacation, and other car work).

 

Mario,

 

I know you're on vacation, but if I don't write this stuff down, I'll forget. Two things to look into when you get a chance...

 

1) Not sure if you still have an EGR valve (or if has been removed). If you do still have one, it might be leaking when it should be closed. This would lean out your idle mixture. Actually it would lean out your mixture at all times, but like any other fixed size vacuum leak, it would have the greatest impact at low RPMs.

 

2) Have you verified that your ECU is getting the START signal? Pin 4 should go hot in START and that temporarily richens up the mixture some.

CO, I'm guessing that one way to check leaking EGR would be to spray the starting fluid at it while the engine is running and listen for change in engine operation. I did just that, but there was no reaction form the engine. When I stuck my finger underneath the valve and pressed on the membrane the engine would drop RPMs significantly and almost die. SO I think my EGR is working properly.

 

Just this past weekend I got a chance to look into electrical signals some more. I used the 280 Z EFI Troubleshooting and Theory and the FSM. However the EFI book was last revised in 1975, so I know there are some things that do not apply to my 1978 model, like the fuel pump trigger, which used to be in AFM and I have it in the Oil Pressure Sending Unit.

Anyway, CO, yes I do get the START signal.

I performed three tests for AFM Resistance (tests 1 -(3a-3c) in the EFI book)Resistance between pin 6 and 8 as well as pins 8 and 9 were showing 180 and 100 Ohms respectively, as indicated by the book. However test 1- (3b) for resistance between pins 7 and 8 should be showing continuity (or small resistance) but in my car it shows around 180 Ohms. Not sure what these pins are for and if this is perhaps because of the relocation of the fuel pump trigger or what. Perhaps this is the result of the previous owner adjusting the fuel mixture inside AFM??

Other than this one discrepancy, everything else I checked returned correct results: Air and Water temp sensor resistance, Control Unit ground circuits #1- #4, Ignition Coil Trigger Input Circuit, Control Unit Power Input Circuit, #1- #6 Injector Circuit, Start Signal Circuit.

I was hoping to find something out of spec, but with the exception of the AFM, everything seemed to be OK...