DCZ

Hi Cygnus, I don't know for certain, but here are my thoughts: As I understand it, the ZXT fuel pump control module doesn't completely ground the fuel pump lead except maybe during periods of maximal fuel demand. It acts more like a variable resistor to ground, so that the fuel pump "sees" less than 12 volts most of the time. My guess is that when the fuel pump is supposed to be "off" there is still enough of a path to ground through the control module that your relay can stay latched. I do know that when I had the stock ECCS in my '73, I did not use the control module and just used the pin 16 output of the ECCS as the positive control of a generic relay. Priming pulse worked as it should and the pump would cut off if the engine stalled so I never had a problem. Get out the volt meter and let us know what voltages you are seeing on the various pins and we might be able to figure out what is going on.

Hey Crashed240z, Did you ever figure out your idle AFR problem? I am having very similar symptoms on my new MS install. Idling pig rich but revs good otherwise. I haven't driven it yet because I'm firming up the wiring. If I try to lean the idle using the V/E table, I get bad off-idle stumbling. stock L28et MSII board V3.57 TunerStudio Stock Optical CAS MS triggering stock ignitor Ford XR4Ti injectors 370cc Stock idle control valve Timing 15 deg. LC-1 AFR

There is nothing to be "wiped" on the ECU so that is not it. The symptoms sound like there is gunk that clogs your fuel pickup which then settles out after some time so that you can start the car again. I know you measured fuel pressure, but did you measure it while the engine is struggling/dying? That is necessary to rule out the fuel problem. You could also run your fuel pickup and return hoses to a gas can and see if that makes a difference. The other thing that seems weird is that your timing seems to be changing on the fly. Maybe your crank angle sensor (in the distributor) is failing as it heats up. If you have access to an oscilloscope you can probe the contacts at the ECU connector (check FSM for which ones) and verify that you have a pulsed signal when the engine is turning over.

I need to spend some quality time with the MS schematics, but if I read you correctly, I'm NOT likely to burn anything in the MS up, since the current sourced/sunk by pin 36 (aka IGN) is limited to 5 milliamps. This may not be enough to turn on the stock ignitor, but the worst that would happen would be that it would not work, or I damage the stock ignitor if I don't adjust the dwell correctly. I am almost convinced to give it a try, and the fact that Randy 77zt ran his that way is confidence inspiring. Good thing I have some more wiring to go so I have some more time to research.

Randy - that's great! Do you remember any details? MS version? Dwell values? Do you know if the signal from MS pin 36 is a positive-going pulse or negative-going? You are the first person I've read about that has done it this way so anything you can describe is helpful. It just seems so easy that I thought maybe everyone with a zxt was using the stock ignitor and thought it was too basic even to mention! Are you no longer using MS on this car?

The data sheet for the BIP373 is Here. Looks like the Base current is 200mA. It also appears from this diagram that the BIP373 is gated by a positive-going pulse. I thought the stock ZXT control unit pulled the corresponding lead on the ignitor to ground, but I'm not sure. Can anyone verify how either system works? The 83ZXT ignitor (power transistor) is p/n 22441-V0800. I haven't been able to find any real technical info on it thus far... Anyone?

Do you know how much current the MS pin 36 can handle? Anyone have specs on the stock ignitor? Sadly, my practical electronic skills are weak. I do know that too much current is one of the quickest ways to "let the smoke out of the box"

I've been researching to install MSII, V3.57 circuit board to replace the stock 83 ECCS and am still unclear on one (or more) point(s): Can you use the stock ignitor to trigger the stock coil, simply using the MS pin 36 signal to gate the ignitor on and off? Do you have to install the BIP373 coil driver IC to do this? Everything I have seen shows pin 36 connected directly to the '-' side of the coil and the BIP373 installed. It seems to me that the stock ignitor should do the same thing that the BIP373 does, which (I think) is to sink some amount of current to trigger the coil. The stock ECCS controls spark (again, I think) by sinking some current to ground to gate the ignitor. So it seems that if the MS can sink the proper amount of current, it could control the ignitor. Has anyone tried this? I don't want to be the first to fry my MS in this way! But if it is this easy, why isn't it written up this way?

Search Hybridz for member HLS30-08077. I think he makes the plug(s) that MSA sells and should be able to hook you up.

If you clean/buff the timing plate you might be able to see the markings. Working from memory, I think the next to the last mark in the direction of rotation is 0 degrees, with each tooth being 5 degrees, so you can measure from about 20 degrees BTDC to 5 degrees ATDC. Someone shout out if I'm wrong! What type/heat range of plugs are you using? Most people have good results with the stock NGK.

Does this sound strange to anyone else? Typically, low compression when dry followed by high compression when wet indicates a problem with the rings sealing. You have one mechanic telling you the head is bad, and one telling you the bottom end is bad. I'm not sure I believe either of them. It was running but smoking when you bought it, and now it's running on three cylinders after the mechanics played with it? My guess is the ancient EFI wiring and components (or has it been swapped to carbs?) are not working or dirty or adjusted wrong or otherwise fooked up and that is why your car is not running well. You need to either educate yourself (this site, zcar.com, FSM etc) or be prepared to pay a LOT of money to maybe get a running car out of the deal.

Okay, I'll spoon-feed just this once Accumulator Filter 1qt long version

Yup, that's what I read too and I was confused. So I guess the stock zxt optical pickup in the distributor looks like a VR signal to Megasquirt, and the "opto-isolator" they refer to on that page is not the same as the optical pickup. That's great that you got your car started! So to recap: For a V3.57 board, driving a single coil and using the stock zxt optical CAS as input: (from the link in your first post) * Jumper IGBTOUT to IGN to send to IGBT ignition coil driver signal out of pin 36 on the DB37. (not needed on a V3.57) * Cut out R57 if fitted on a V3.0 (This won't be there on my units, though.). * Our assembled V3.57 boards, if not fitted for direct coil control, will have a jumper from JS10 to the center hole of Q16. Remove the jumper from the center hole of Q16, and reroute it from JS10 to IGBTIN. * Solder a BIP373 into the Q16 slot, using a mica insulator. Then: Jumper JP1 on positions 1,2 Jumper J1 on positions 3,4 1K resistor soldered onto R57 pads Tweak potentiometers on R52 and R56. Megatune (TunerStudio) settings: * Set Spark Output to "Going High (Inverted)." Setting this wrong can overheat the BIP373s or damage the coils. * If using MS2/Extra, set Spark A output pin to JS10. That's it for ignition control, right? Keep us posted on your progress, I'm a few steps behind you and anxious to catch up!

I'm confused. If you are using the stock crank angle sensor, isn't that an opto-isolated trigger? Why do you have the VR+pullup trigger input setting? I read over the MS manual section for this and it is not very clear on this point.

The 83 CAS produces 2 trigger signals, one for the 360 slot section of the wheel and one from the 6 slot section of the wheel. I am researching this for my own conversion and have not yet found (or missed reading) anything that says which signal MS uses. Could it be that you are supposed to use the 6 slot signal and not the 360?

PM'd

That is NOT a power transistor! That is the ballast resistor. It's purpose is to protect the points in the distributor, which the OP does not seem to have since he says he has a Pertronix ignition. xplosive - hard to diagnose your problem from afar, it could be several factors. Best to go back to basics - fuel, air, spark and verify what you have or don't have when the no-start condition exists. Could be crud in the tank, could be "vapor lock" (search fuel percolation which is a more accurate term), could be an intermittent ignition problem. You will most likely have to re-create the problem and go from there.

PM'd

Adjust the tps by loosening the mounting bolts and slightly rotating the whole tps. It is a switch so it should be closed at idle and open as soon as you crack the throttle (or the other way around, I forget!). Get a Factory Manual and follow the EF/EC section to verify all your harness connections. This is easy and VERY IMPORTANT. All you need is a volt/ohm meter. Also you might want to advance the timing a bit (rotate distributor CCW). Static timing at idle is ~23* BTDC on the 83 turbo.

There is a connector underneath the steering column cover that can come loose and cut power to your gauges. This happened to me and I don't recall the wire color but it is a single bullet connector. When I took the cover off and re-seated the connector my gauges started working again.

Many of your symptoms point toward debris in the fuel tank clogging the input to your fuel pump. However, this is a 33 year old car with who-knows-what done to it by previous owners so there can be many contributing factors. My best advise to you would be to get a Factory Service Manual (search this site for links to free download) and follow the troubleshooting sections in it. You don't need any fancy tools and you will become a lot more knowlegeable about your Z than any of your local parts swappers, er, mechanics. Have Fun!

I see now that you are talking about the bolts on the ends of the bumpers (my mistake) but I agree with mxgsfmdpx that you do not have to move the fuel tank. I've removed and reinstalled the rear bumper several times on several 240zs and never had to mess with the fuel tank. You just need the right wrench and a little patience.

I've never had any problem removing the bumper from a 240Z. The bumper bracket bolts on from the outside. Never had to mess with the fuel tank for that. Later models (260, 280) have bumper shocks which are more difficult to remove.

On a related topic, I have been reading up on controlling spark with Megasquirt using the 82-83 optical dizzy and I haven't found the answer to my question: When first converting to MS, do you leave the distributor alone so that you have a static "mechanical" timing of 23BDTC like you would with the stock ECCS? That way the numbers in the timing map in MS would just be advance beyond the 23 degrees. Or do you rotate the distributor so that your static timing is 0 degrees and the MS advance numbers reflect the total timing advance? Maybe this becomes obvious once you start playing with the actual system, but so far I have only been reading as much documentation as I can find.

Dan Neil is IMO the BEST automotive writer ever. He used to write for my local paper and I would wait for his column every week. Then the bozos at the paper fired him for some undisclosed reason and he went to LA and won the Pulitzer! If he can translate his sophisticated writing style and humor to a TV show format they would have a winner.