Need some help 72 to 78 EFI swap

[MikeyZee]

My son has a 72 240z and we are putting in a 78 EFI l28. We are really close and we were both hoping to get it running today. Before we pulled the 240z motor everything worked fine on the car with the original l24 and the auto trans it was a dog though.

 

The engine is all installed as well as the 5 speed. We have done allot of work on this car and we are so ready to have it running. I was hoping to get it running today but I don't know if I am missing something or what. So far this is what we have installed.

 

Parts installed from the 78 280z

L28

5-Speed Trans

ECU

Manifold

Injectors and Rail

Fuel Pump

Internal regulator Alternator

Fuel Injection Wire Harness

Umbilical Harness

Dropping resistors

Main EFI Relay

Fuel Pump Control Relay

Fuel Pump Relay

 

As far as the wiring goes we had to merge the 280z and the 240z harnesses. I have studied both harnesses from the factory wire diagrams for the 72 and the 78. This is what we did as far as that goes.

 

Fuel Pump

Used the factory installed 240z auxiliary Fuel Pump wire harness tied in to the Umbilical Cord

 

EFI Main Relay

Plugged into the factory 280z Wire Harness

 

Fuel Pump Relay

WB to Fuel Pump Control Relay

GL to Fused Battery/Starter Constant 12v (same as the Fusible Link would be)

GL to Fuel Pump (+) tied into the Factory 240z fuel Pump Harness

 

Fuel Pump Control Relay

WB to Fuel Pump Relay

L to the Alternator S Terminal

BY to Starter Connection (Ignition Start)

WB to Umbilical WB

YB to Oil Pressure Sending Unit

 

ECU to Body (Umbilical)

L Ignition Box (Jacobs) Tach Connection

GL Fuel Pump (+) Fuel Pump Relay

WB Fuel Pump Control Relay

BY Starter Connection (Ignition Start)

 

We removed the Factory 240z Alternator and installed an Internally Regulated one.

We also did the conversion steps by connecting the BW and WB then the W and Y together.

We did not install the diode because the connector to the Factory 240z Regulator does not have the WR wire.

 

The car was an auto transmission so it has the connections for the Inhibitor Switch. Do those connections need to have anything done with them?

 

At this point we cannot start the car. It will not turn over at all. We can hear the relay under the passenger side dash clicking but that's it. The fuse for the tail lights also keeps blowing so I am sure I really got something screwed up!

 

Anybody that can help or who has done this please chime in. Thanks in advance for the assistance.

[MikeyZee]

OK.....now I feel kinda stupid. It looks like I made a mistake. I hooked up the kickdown connectors from the 240z harness to the reverse switch on the manual transmission. I just wasn't thinking. It also looks like half of the Inhibitor switch harness should be connected to the reverse switch on the manual trans. The other two look like they should be connected together to allow the starter to engage. Can anyone verify that for me though? I have looked at the 72 240z wiring diagrams but they don't have anything referencing the auto trans or inhibitor switch. The diagram for the 78 280z does have the detail on the inhibitor switch auto trans etc. It says for the 280z the wb and wb are the inhibitor leads and the g and g are the reverse leads. Are they the same color wires for the 240z?

Thanks again.

Edited August 9, 2010 by MikeyZee

[Tennesseejed]

Were you able to get the engine to turn over?

 

I'm not familiar with the 240Z or 208Z inhibitor circuit so I'd suggest circumventing it, if possible, until you can get the car running.

 

Pin 76 on the fuel pump relay powers the starter solenoid. Unless your starter is not wired properly to battery+ & chassis, you're probably not getting 5VDC on the starter solenoid. Check the solenoid lead with the ignition on start as well as Pin 76. If you don't have voltage there, you've got a different problem.

[DCZ]

Sounds like the starter inhibitor switch that was on your auto trans but now is missing. The auto had a switch that closed when in neutral or park. You can jump the wires that went to that switch (could be dangerous because the car can start in gear), you can plug the wires into a neutral safety switch if your manual trans has one (my T5 out of an 83 turbo has this) or you can use a switch on your clutch pedal that closes when it is fully depressed.

[MikeyZee]

I think we got the issue with the inhibitor switch straightened out. Just not sure if everything else is OK. I have not had the chance to short the switch connections and terminate the others on the reverse switch on the manual transmission. I did not see a neutral safely switch on the wiring diagram on the 78 280z. I do not have one on my manual transmission either. I am not sure the 78s had this safely feature but adding one may be a good idea. Thanks for the info!

[Tony D]

Clutch Idiot Interlock is not there, and not required.

I wouldn't add it, just another thing to go wrong.

I have disconnected that 'feature' on my Y2K Frontier because personally I have a HUGE problem putting a 1700# poreload on an unlubricated center thrust bearing of the engine. I can start it in "N" and not have any thrust bearing wear at all...

 

Decisions, decisions, longer bearing wear, or consequences for starting the car without putting it in "N" first (and concurrently forgetting to set parking brake when shutting down car per instruction manual)

 

I'm not a fan of worst-case 'cascade failure' scenarios. I can remember to set the Parking Brake and put it in "N" before I start.

 

As for the inhibitor switch, yes, you have to jump it. My suggestion is to not JUMP the switch, but run the wires to the console and install a factory switch in one of the existing holes so when you park the car you can enable a 'cranking disconnect'---nice anti-theft feature. I did this on my buddy's 69 Corvair when we did the conversion. Worked so well he forgot about it and after a long parking stint in his barn confounded him! I showed up, flipped the inhibitor switch right there on the dashboard and he started swearing as he remembered it was old-had to flip that switch as he exited the car.

 

It had been close to 7 years since parking it, and he forgot it needed to be flipped up and who turns on the fog lamps when the start the car, eh?

[MikeyZee]

OK....looks like we got the no crank situation worked out but still won't fire up. I can't hear the injectors pulsing, there were a couple backfires so I wonder if that means we are getting spark. I have to check to see if we are getting any gas or spark for sure though. We ran out of daylight. The fuel pump however always runs once you have turned the key to the on position. The only way to stop it is to disconnect the battery terminal. We reconnect the battery terminal and it does not come on until you try again to start it.

Thanks again!

[MikeyZee]

OK....At this point we have fuel getting in the combustion chamber cause the plugs and they smell of unburnt gas. The plugs are firing too. We pulled the plug and on crank they fire. I have the fuel injection (blue lead) terminated at the tach output of the Jacobs ignition. The #10 pin is getting power on the ecu and the #5,16,17, and 35 all have continuity with the ground. The engine cranks over fine but doesn't ever seem to ignite. All the fusible links are fine and all seems to power up and shut down fine. Is there anyway to have the timing 180 off or anything? I'm at a loss here.....

[Pharaohabq]

Well if you mucked about with the 78 engine, you might have messed up the timing. If not, you might just check your plug wires are correctly installed. 153624 you've got fuel and spark so it's got to be something like timing. Check that the rotor is pointed at plug 1, that the main crank is at 0 on the timing plate, then open the oil fill cap and look in to try to see the cam lobes for Cyl1 should be pointing up in a V, notating compression stroke. if this is all correct, then it's not a timing issue.

 

Electrics can be tough to figure. What connections do you have for constant 12v and switched 12v in the 280Z harness?

 

Phar

[MikeyZee]

The plug wires are all on correctly and all that was done to the engine was a new head gasket was put on. Nothing was turned on the engine or head when that was replaced. The distributor is keyed so I don't think that can be in wrong. When it's firing I can't hear the injectors pulsing. I need to check them to see if they are getting power again. I wonder if the plugs are getting wet from the cold start injector only. Another wrinkle is that the fuel pump is always on when the ignition is on the run position. Maybe it's shutting off the pump when we are trying to start it.....hmmmm? I know that is not supposed to do that. I wonder if somehow I got those mixed up. The Fuel Pump Control relay powers up the Fuel Pump Relay which passes power to the Fuel Pump. I'm guessing the Fuel Pump Control Relay is not wired correctly or is faulty or stuck or something. I have wired it like this.

Blue Wire=Alternator (L) Terminal

Yellow/Black=Oil Pressure Sending Unit (I have this spliced into the original Wire for the Oil Pressure Gauge. I noticed a 2 terminal sending unit and the manual shows 2 terminals as well. Would this be the wrong sending unit I have installed?)

White/Black=Connected to the umbilical harness White/Black and then has a 12v start and run powering it.

It seems like we are so close but dang this stuff is not exactly plug and play...lol

[Tennesseejed]

Have you verified that Coil (-) is connected to Pin 1 on the EFI unit? Do you have 12VDC on the injectors?

 

If the injectors aren't firing, the two most likely culprits are lack of power to the injectors or lack of signal to the EFI box to know when to fire the injectors.

[MikeyZee]

This weekend we did many tests on the components of the EFI on the car. This is what we came up with.

The fuel pump control relay powers the fuel pump relay whenever there is power introduced to the BW lead on the relay (ignition on) power and does not need to have oil pressure to power the fuel pump. Thus our fuel pump always runs. The fuel pumps also runs during start so I don't think this would be the problem with it not starting.

 

The fuel injectors are not pulsing at all. The injectors are getting voltage with the key on. I do not get the injectors to pulse on the 3rd break.

The EFI relay comes on so I did the tests outlined in the EFI Bible. All the tests show the wiring is good and the system is getting voltage where it should and there is continuity where it should be.

I went ahead and bought another ECU as suggested in the EFI Bible.

 

One of my concerns is maybe it's the electronic ignition I am using. I have a Jacobs Electronics CD ignition and then to get the tach to work we had to add a MSD tach addapter. The ignition and tach were both working on the L24 with the electronic distributor. I am sending signal to the tach and ECU with the tach wire from the Jacobs box. Is this a sufficient signal for the ECU?

 

I did notice one thing about the ECU and connector. The ECU is a11-600-000 and the #21 has no pin however the harness has a connector in #21 which as I read is for the cold start injector. Has anyone else noticed this? Is the 78 ECU unique to the 78 or are other model year ECUs? I did a search and the a11-600-000 shows that it is for a 76-77-78.

If anyone has any suggestions that would be greatly appreciated.

[Pharaohabq]

I believe that though the Distrib is keyed, it is possible to get it in 180 deg off. possibly the case. also yout timing could be off if you hemoved the head, I would really check to be certain your timing marks are all lined up properly.

[Tennesseejed]

 

One of my concerns is maybe it's the electronic ignition I am using. I have a Jacobs Electronics CD ignition and then to get the tach to work we had to add a MSD tach addapter. The ignition and tach were both working on the L24 with the electronic distributor. I am sending signal to the tach and ECU with the tach wire from the Jacobs box. Is this a sufficient signal for the ECU?

 

 

I'd wager that the source or your problem lies in this paragraph.

 

If you don't already know, look into how the Jacobs Electronics CD ignitions operates (I have no clue). The stock L28 operates by maintaining a constant 12VDC on the coil and the ICU (ignition control unit) operates the sytem by dropping the voltage to ground which, in turn, sends a signal to the Pin 1 on the EFI box to send fuel. Until your last post, I was sort of assuming that your reference to "ECU" in the first post meant you had installed the stock ICU. Now I understand that your are using ECU to refer to the EFI box.

 

I ran into this problem when I installed my MSD 6A box. The MSD unit does not maintain constant 12VDC on Coil. Instead, the MSD system sends a positive pulse to the coil upon an ignition event. Using the MSD 4910 adapter I was able to "trick" the EFI box into reading the stock signal.

 

I don't know much about the stock 240Z electrical system other than I loved the '70 I took to prom and the '73 I owned after High School back in the day. I do know that the 240Z tach is current driven off the plus side of the coil as opposed to the 280Z tach which is driven off the negative side. Given that your original post indicates that you have installed a 280Z EFI harness, I'm not sure this relates to your problem, but you should consider whether any of the original 240Z wiring is related to your problem.

 

If your Jacobs unit is a negative voltage ignition unit (does not provide constant battery voltage on Coil +), then you should focus on finding a way to drive the EFI box as your solution. For example, the MSD box has a tach out pin which can be used to drive EFI. Although I did not use tach out to drive my MSD installation, it also requires a tach adapter.

 

Does Jacob Ignition have a support page that would help?

[MikeyZee]

tennesseejed- Thanks for the reply. I currently have a MSD tach adapter (8920) running the factory 240z tach. I am thinking I will need to run both a 8920 for the tach and a 8910 for the ECU/Fuel Injection pulse. I just acquired a MSD 6a and a SS blaster coil, a more standard setup always seems to help. I mean it's been done before. The output of the Jacobs ignition should be the same as the MSD but I'm not real sure. I thought the 8920 would drive the signal correctly for the fuel injectors if I read the other posts correctly. I read somewhere that someone was using both the 8910 and 8920 in a configuration like mine. The alternative of course is to convert to a 280z tach but then I would still need one adapter. Correct? Of course I'm more concerned with getting the engine running and the tach can come later.

[Tennesseejed]

Should clarify my last post - I used the 8910 adapter, not "4910".

 

Looking at a '77 wiring diagram, the tach and EFI Pin 1 are both fed off the Coil (-) Blue wire. If you switch to MSD6 you should not need both adapters.

 

There are at least two ways to fire OE EFI with the MSD box. I used the 8910 adapter in series with the Coil (-) post and the blue wire (Red wire to post/White wire to Blue wire). Can't say it was the best possible solution, but it worked well.

 

The 8920 adapter is normally used in between the MSD tach out pin and either Pin 1 or the blue wire upstream of the tach resistor. I have never installed an 8920 so not much help there. Search the Ignition subforum for MSD6. There are several somewhat confusing/helpful threads. I did find MSD tech help to be pretty helpless when I called.

 

I'm still using MSD6 with a MSII fuel only install. It works well enough that I'm having a hard time finding the energy to upgrade to MS3 and attempt sequential spark. Though I probably will next Spring.

 

Currently my MSD6 box is located behind the passenger firewall on the floorboard. Not ideal. The unit can also make a fair amount of noise. If I were to install MSD6 again - or just get off my butt for 30 mins - I would (re)install the MSD box inside the windshield wiper bay. I learned that someone on here had done that after my install was finished.

 

I have a spare 8910 adapter if you interested. Send a PM.

 

Edit: Given the current driven 240Z tach, you may need both adapters after all.

Edited August 18, 2010 by tennesseejed

[MikeyZee]

I am looking at some diagrams here (slacking off at work). One setup looks like someone is running the 8920 to the blue (signal for the EFI) http://forums.hybridz.org/index.php/topic/17205-msd-6btm/page__p__125166__hl__%2Bmsd6a+%2B8920__fromsearch__1#entry125166 I'll try that and see if that gives me any results but I am thinking I will have to revert that back to the configuration I have now and add an 8910 as well. The actual configuration I have now has the older 8920 with the white going to the tach signal from the ignition, black goes to ground, violet feeds the 240z current controlled tach and the red.....lol....no connection! Yeah, it's working and accurate. My son is getting restless to get his Z running again. He is a teenager and has no patience at all I don't want him to lose motivation and interest. I want to keep him motivated but we are in a "holding pattern" now. I'll PM you about the 8910.....Thanks!

[MikeyZee]

Thanks to everyone for the input and food for thought. I found a post earlier about the 8920 tach adapter and a neat little schematic. Like I said I have an 8920 for the 240z tach. I hooked hooked it up as the schematic says (added the switched power to the red lead).

Then something that Pharaohabq said about it being 180 out. I thought maybe I got it off a little when I had the head pulled. We pulled the valve cover tonight and turns out the cam was lined up perfectly to the crank. Hmmm? But the dizzy was out 180. The dizzy was the 79 280zx dizzy that we had put on the L24 to convert it to electronic ignition. Guess we grabbed the wrong on! The ZX dizzy is 180 out from the 280Z distributor! Swapped it out for the correct one from the 280z and started to try to start. Sprayed a little starting fluid in it and fires right up! WOO HOO!

It's just a little loud with the open header!

 

The next thing we have to figure out is why it won't start without the starting fluid. The 78 280z wiring diagram has the position #21 connector terminated to the cold start injector and thermotime switch. Pin #21 on the ECU has nothing in there, no pin to connect to at all. The two ECUs I have are a11-600-000 and neither one has a pin in the #21 position. Any one run across this before? I have not actually tested to see if the cold start injector is working at this point. I'll have to check this tomorrow. If anyone has any insight about this please let me know.

 

Another thing is the tach seems to be reading high. Barely idling at about 700 RPM (by ear) shows as it's at 1100-1200 RPM on the factory 240z tach. I have yet to put another tach on there but it just seems inaccurate. Wasn't there a cure for this by putting a resistor or diode in the signal line? If not I guess I can either get a 280z tach or a 8910 tach adapter for the EFI and use the 8920 for the tach.

Any help is appreciated!

Thanks all.

[MikeyZee]

"With regard to your remaining car issues, I suspect your no start condition might be related to either (1) the fuel pump is not getting power on the key "start" position or (2) at very low (starting) rpms, the EFI box is not getting a strong enough signal on Pin1 to know to send fuel to the cylinders.

 

I think in your thread you mentioned that the fuel pump was running in the start position, but the simplest way to check is to disconnect the fuel line after the filter and turn the key. Might be a little messy, but it's foolproof."

 

The pump is running in "on" and "start" 13.2 V or whatever the battery is reading at that point. I just spray about half a shot of starting fluid and it fires up like a charm.

I can fool the entire cold start system too by putting 12v + and - on the leads.....hear the injector click once then turn it over and starts right up. It just seems like the cold start system in my 78 is not complete with that #21 pin just not being on any of my ECUs. Maybe the thermo-time switch when energizes shorts against the ground and sends the signal back to the cold start injector. I checked to see if either of the pins on the thermo-time switch are grounded to the chassis and one is. That may be a possibility because the thermo-time and the cold start injector are in parallel.

[Tennesseejed]

Mike,

 

I'm pretty much out of ammo, but let me tell you what I think I know.

 

First, your car should eventually start regardless of whether the cold start injector is firing or not. During cold start operations the cold start injector only adds extra fuel until the themotime switch opens the circuit. I can't imagine it's that cold in Colorado in August. It was 70degF in Anchorage today.

 

I downloaded the '78 FSM from xenons30.com because there are differences between the '75-'77 and '78 years. I own a '75. The '78 FSM shows Pin 21 on the EFI box being used for the cold start injector circuit. Pins 19, 20, and 22 are not used. Are you sure you have a '78 EFI box? Because Pin 21 is used according to the FSM. ???

 

Second, the cold start injector should have 12VDC with the key on the "start" position. After the engine starts, the cold start injector should continue to have 12VDC from Fuel Pump Control Relay and will continue to have 12VDC so long as the engine runs. Only when the thermotime switch heats up will the cold start injector cease to fire. At least that is the way I read the '78 FSM.

 

Final thought is that your fuel pump should not be running while the key is in the "on" position and the car is not running. I don't know how, or if, this might be related to your no start condition, but it is a nontypical condition.

 

Actually, one more question and a thought - Are you running MSD6 yet or the still the Jacobs ignition? And don't worry about your tach operation until the car starts reliably. The tach does not affect operation of the ignition or fuel injection circuits in any way. Worry about getting the tach to work correctly later.

Edited August 21, 2010 by tennesseejed