Sticky EFI thread, please chip in FI guys!

ElkRidder280 · December 22, 2014

You can download it from this site. http://www.xenons30.com/reference.html
If you scroll further down to the "other" section you will also find the EFI bible. I have read that the EFI bible on the xenon130.com site is better, but I can't confirm it.
Goodluck
Chas

EuroDat,

Thanks for the help and directions to the above page.Got the 78 FSM now. I just checked out the EFI manual that is posted and it is the same 1975 model year that I currently have. Which unfortunately does not match up with the ECM 35 pin connector on the 78's. There is a nice trouble shooting section in there, but my 78 does not have some of the pins listed. I believe they have changed some of the electronics and its making it hard to figure out just what could be causing the running problems.

Thank you again for the link!

ElkRidder280 · December 22, 2014

In the EFI manual on page 53 "air flow meter fuel pump contacts" test for car not starting is says to check continuity between leads 10 and 20 with the AFM flap in different positions. However, my North American (non-California) model does not have a pin 20 in the ECM connector. Anybody got any thoughts on testing this?

Cheers!

Zed Head · December 22, 2014

The newer Fuel Injection Guidebook is in the link below, it's for the S130, not S30. It's from 1980 but covers all previous years. 1978 doesn't use the fuel pump contacts, it uses the oil pressure switch or the alternator current, through a relay. You'll need the 1978 FSM, Engine Fuel chapter, to see that.

Does it run for an actual few minutes or a measured 15 - 20 seconds? The word is that for 1978 if you disconnect the oil pressure sender that the fuel pump will get power when the key is On. It's a flaw in the design, but could be handy.

http://www.xenons130.com/reference.html

EuroDat · December 23, 2014

I have heard from others about these issues with the 78 model. On the 78 they started changing things a bit and some things seem more like the S130. Thats why I mentioned the other EFI bible on xenons130. I have a 77, thats why I can't confirm it.

Maybe Fastwoman will see this and chip in. Sarah has a 78 and knows a lot about that model year.

Im on a smartphone so I hope this is not to challenging to read.

Chas

ElkRidder280 · December 23, 2014

The newer Fuel Injection Guidebook is in the link below, it's for the S130, not S30. It's from 1980 but covers all previous years. 1978 doesn't use the fuel pump contacts, it uses the oil pressure switch or the alternator current, through a relay. You'll need the 1978 FSM, Engine Fuel chapter, to see that.

Does it run for an actual few minutes or a measured 15 - 20 seconds? The word is that for 1978 if you disconnect the oil pressure sender that the fuel pump will get power when the key is On. It's a flaw in the design, but could be handy.

http://www.xenons130.com/reference.html

It runs from a cold engine for about 2 min and then stalls out. If I let it cool down then it will start up and do the same thing again. It runs rough during its running time, but it can be reeved up to about 3-4K. Once it starts to warm up, and after it dies, it wont start again for a while.

Thanks for the tip on the oil pressure sender and fuel pump interlock bypass.

ElkRidder280 · December 23, 2014

Zed Head and EuroDat thanks for the help. I just got the EFI manual for the 78 and I will have to get back under the hood and steering wheel and see where the pins go and what is working and what is not.

Cheers

Zed Head · December 23, 2014

Does the exhaust get a gassy smell before it dies? Kind of sounds like your coolant temperature sensor is disconnected, causing the ECU to supply fuel for a cold engine. Or that you have a vacuum leak and the mixture is only rich enough to overcome the leak(s) when the ECU is supplying extra fuel when the engine really is cold.

The Guidebook shows how to check resistance of the coolant temp. circuit at the ECU connector. That will show you if the ECU is getting good information.

Once you run out of the simple checks, the best route is to get a multimeter and run through all of the electrical tests. They don't take as long as you would think and when you're done you'll probably have found a few simple things to make better in addition to maybe finding the big problem.

If everything checks out then you can move on to the odd problems, like fuel pumps that are corroded and overheat after a few minutes of running. Two of us have had those.

EuroDat · December 23, 2014

Another website to get usefull info is AtlanticZ http://ww.atlanticz.ca. Check their Tech Tips. If you are new or firmiliar with Zeds its has a lot of handy tips. You will see Blues Zed in a lot of the how to's.

Your problem sounds much like what Zed Head already mentioned, so I wont repeat it. The temp. sensor cable often gets roadster over time and the connector falls apart. That happened to mine.

Chas

ElkRidder280 · January 1, 2015

Does the exhaust get a gassy smell before it dies? Kind of sounds like your coolant temperature sensor is disconnected, causing the ECU to supply fuel for a cold engine. Or that you have a vacuum leak and the mixture is only rich enough to overcome the leak(s) when the ECU is supplying extra fuel when the engine really is cold.

The Guidebook shows how to check resistance of the coolant temp. circuit at the ECU connector. That will show you if the ECU is getting good information.

Once you run out of the simple checks, the best route is to get a multimeter and run through all of the electrical tests. They don't take as long as you would think and when you're done you'll probably have found a few simple things to make better in addition to maybe finding the big problem.

If everything checks out then you can move on to the odd problems, like fuel pumps that are corroded and overheat after a few minutes of running. Two of us have had those.

Ok thanks for the above post! Very helpful. I have quite a few years working on FI cars and especially the BOSCH systems, but all in BMW's and this is my first Z car. I did run through the checks today with a DVM and the big glaring problem was the "Thermotime Switch" on page 19 of the EFI book. It was supposed to have 740-940 Ohm resistance at the coolant temp today and it was around the six mega-ohm range.

However, when I tried to get this part at the local parts store, then only had one thing listed as a "coolant temp switch". Now the diagram shows shows three different sensors screwed into the thermostat housing on this 78 280. One I take it the "Thermotime switch" than controls the cold start system, the other two I don't know. Any ideas?

I have a picture of the one I purchased today, but can't seen to figure out how to upload to this site. I also have some screen captures of the tech manuals, but the same problem.

Cheers,

ElkRidder280 · January 1, 2015

Also,

Today with the 78, its about 25F today in western Oregon and the car started right up and idled for about 15 min. I could even rev her into the 3-4K range with no problem or hesitation. Then once she warmed up to around 120F(coolant) she started to stumble and misfire. Here are a couple questions I have and was hoping someone might be able to clear up.

1. on page 19(and 49) of the 78+ EFI bible is that Thermotime switch the same that is tested on page 79 of the same book?

2. would a malfunctioning Thermotime Switch/Coolant temperature sensor cause the symptoms I talked about above?

Thanks in advance!

PS: Does anybody know of a good parts source for this year of car?

EuroDat · January 1, 2015

Also,

Today with the 78, its about 25F today in western Oregon and the car started right up and idled for about 15 min. I could even rev her into the 3-4K range with no problem or hesitation. Then once she warmed up to around 120F(coolant) she started to stumble and misfire. Here are a couple questions I have and was hoping someone might be able to clear up.

1. on page 19(and 49) of the 78+ EFI bible is that Thermotime switch the same that is tested on page 79 of the same book?

2. would a malfunctioning Thermotime Switch/Coolant temperature sensor cause the symptoms I talked about above?

Thanks in advance!

PS: Does anybody know of a good parts source for this year of car?

Your question 1: No they are not the same. Page 19 & 49 refer to the Thermotime temp sensor (for the Cold Start System circuit) and page 79 is a test for the temp. sensor for the ECU.

Page 64 has a goed overview of the two temperature circuits. (Pin 13 and Pin 21 on the ECU connector)

If you want to test the Thermotime circuit. It is on page 98 Test #3 - (3).

Poor connections are a big problem with these cars and very important in these old (analoge) systems. I replaced my connectors with aftermarket on the Injectors (for easy testing) and OEM on the Temp.sensors. See attachments

I don't have much info on the 78. Just about everything I have is based on the 77.

Here is a photo from AtlanticZ and a snapshot of the wiring for the 280Z 1978. Hope thats the right diagram.

Good luck with hunting it down.

Chas