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I think im chasing my tail on this one.... This morning i repalced a few fuel lines as 5-6 started to leak and crack from the fuel pressure. I also used some electrical cleaner to clean all the electral connectors. I started to engine and it can now run past 10 seconds without fail. not sure why. but great! the issue now is its running very poor. Rich and extremely low idle. I tried adjusting the AFM and idle adjustor but nothing is effecting it. I double checked the ECU connections and now im not seeing any ohm readings on the appropiate pins for the AFM and the TPS. I checked the TPS internals and connectivity is all there. it must be the wiring somewhere. In the end i wanted to get the engine running and it is! so thats fantastic. I think im done troubleshooting this thing and im just going to leave it as is for the moment. I plan on replacing this entire ECU/AFM & fuel system anyways with megasquirt or similar system. No need to fix this system if im going to be getting rid of it. Now its time to tear things thing down to the frame.

Easy test, take the ballast RESISTOR out of the equation: Take the G/W wire OFF the ballast, hook it up to the B/W that's connected to the other end of the ballast. Run the engine. Is it better? Is it worse? Don't notice a change at all? (Better: leave the ballast out - figure a good way to connect the G/W and B/W permanently cuz VOLTAGE. Worse: hook it back up the way it was. No diff: Hook it back up the way it was - if you're sure there was no change.) (I haven't said yet what I'd really recommend which is: replace all your harness wiring, especially the engine bay harness which suffers the most degradation over 50+ years of living on this Earth... Few people listen - even me - I'm just barely doing that in my own car (and it turned 50 last year).)

Hi Site Been a while….not sure, but whatever adds .080 inches….if they are .040 inches, 2 would do. Don’t hesitate to call Eiji….tell him you’re my cousin and if wants to keep eating steak at our house, he needs to be nice! 🤪 He’ll sell you the right stuff.

O.P., you should probably pull a spark plug or six and see if (how much) they are sooted up. The Fuel Pressure Regulator (FPR) on an EFI engine is "vacuum referenced" or Manifold Absolute Pressure (MAP) referenced. Meaning it has a hose connection to the intake manifold. The FPR is supposed to maintain a fairly constant fuel pressure differential with the manifold pressure. Nissan uses 2.5 BAR or 36.3 PSI as the required differential. That means WITH the engine NOT RUNNING and fuel pump RUNNING the pressure to the fuel rail and injectors should ~36.3 PSI. When the engine IS running, the FPR will SUBTRACT the manifold pressure while under VACUUM or ADD the manifold pressure if under boost (positive manifold pressure). You don't need to consider boost. But, say you have 10 PSI of VACUUM while the engine is running at idle, your pressure at the fuel rail and injectors should be ~26.3 PSI (36.3 - 10 PSI). First: The ECU DOES NOT get the "tach signal" - that circuit if for the GAUGE ONLY. It is pointless to look for it. The Electronic Ignition Module figures out when to send a signal for the coil to fire - it gets the information from the distributor electronics (pretty sure - I haven't handled the original Bosch L-Jetronic for a blue moon...) Second: Have you tried operating the engine WITHOUT the cold start valve? Disconnected from wiring and/or fuel? (IS your engine only running on the cold start fuel??)

Thanks - another (perhaps market specific ?) - the U98. Do you know which year (s) please ?

I'm using a U-98 manifold which I bought in Australia. It has no emissions ports in the casting.

The S30 parts constantly evolved over the years and not at set periods - Nissan introduced changes (sometimes improvements) asap in mid-year/production model runs. This also applies to the cast-iron exhaust manifolds and so far for the 240Z alone, I've noted the following cast numbers (visible under the ports 5 + 6 : U87 N42 N47 N33 E30 - this I know is the European version. Generally, I believe, the different parts denote different methods by which Nissan passed their cars through certain anti-pollution controls (?) however all appear to be of the same dimensions......except the 1973 (last) version before the introduction of the 260Z.. This manifold is longer towards the flange which is itself at a slightly different angle. This means that the 1973 downpipes were shorter than the previous AND post versions and I'm trying to foind one please. In the absence of the real part, I'd would like to at least know the casting code, please, on the 1973 OEM exhaust manifold ? Can you list here any other manifold casting numbers with their car model and year please ? Many thanks in advance.

Ok thanks but would you know the casting number on the OEM exhaust manifold please ?

Sorry...Downpipe sold.

Yes, he did and on the same day you apologised - thankyou. The beauty of forums such as this compared to the social media is that information remains visible, unswamped by daily 'chaff' to refer to by new members. But that is a double-edged sword and without having the courtesy and rerspect to edit or delete your unfounded comments, they remain there in perpetuity and rare is it that anyone will scroll further down once having seen your post ! "If you haven't got money in deal I'd seriously think about MSA ceramic coated headers. I've got 6to1s on both my cars and very pleased after 10 years of running them with MSAs 2.5" aluminum, I think, to the back bumper. They have other configurations but I like the sound and backpressure of the the 6to1. It's loud but only if you chose. Stay out of it until you get away from neighbors and then who gives a flip. If the guy won't talk to you, it's not going to have a wonderful ending no matter what you pay him. Get out while you can." You suggested the cheapest mild-steel headers available on the market and have you really inspected the welding quality and the flange in particular ? A 6-1 header is not even conceived for the street but track and drag runs in order to dump as much exhaust gas as quickly as posisble.....even then Nissans' own race headers were always 2-1 and their S20 exhaust line a full twin-pipe system to the rear to improve torque for the 'little' 2.0ltr. And MSA's exhaust line in not made of aluminum lol but the same mild steel and heaven knows why they haven't proposed a resonator (not just for the noise and it IS loud) but for the engines' performance (google exhaust scavenging). You 'like' the backpressure ! Your exhaust system is totally de-restricted meaning you have an absolute minimum of restrictions to the exhaust gases with a paradoxal low exhaust-gas velocity, especially during street driving. This is losing you power, most likely between 10 and 20% - call it 15. On a stock L24 making 130 hp DIN max, adding your exhaust is in fact reducing your net power down to perhaps 110hp....it sound loud, it sounds fast but stick it on a dyno and weep ! You'd be much better off fitting MSAs 6-2 (Pacesetter), same exhaust line but having your exhaust shop fit a resonator just behind the transmission....costs a bit more but the benefits are real. That's where MSAs' technology stops and I was fitting them and also the twice-pipes kit back in the early '90s because it was all I could find...back in the day of catalogues and sending faxs to order ! :-) I chose to produce more expensive, I'll admit, but still more affordable than the parts available in Japan and still the only single stainless-steel pipe system that doesn't have an over-sized diameter (3" for a n/a engine - get outa here ! ) which are efficient for road and track use for different size engines and also with different characteristics (compression ratios, camshafts etc.....) and also different driving styles 'cos I don't believe one size fits all. https://www.roadandtrack.com/new-cars/car-technology/a14530205/what-is-exhaust-backpressure-and-why-is-it-bad-for-horsepower/ I'm not sure that you're best placed to advise anyone on exhaust choice. You told texasz to get out while you can cos it's not going to end well whatever he pays ! Perhaps you should ask him how it ended...........

Hi - I read this : "Whatever you're writing in your messages must be something he's avoiding." 1) assumption without proof that I'm avoiding him 2) Insinuation that there is a sinister reason I'm avoiding him "must be'' Any reason he would be avoiding you? 3) Insinuation that there is a sinister reason I'm avoiding him reinforced Not a good look for him if there's no good reason. 4) Negative prediction and quite frankly pointless statement - I don't ignore anybody, who would ? Help, where ? Tagging me here wouldn't if I was avoiding him here.....which I wasn't ! Why DM a guy who doesn't respond to a customer's messages? I implied DM the enquirer, in this case texasz, with your opinions w/out facts rather than imply publicly what you did - that's not helping my business nor the potentiel customers' confidence - please think. Have a great day now - it's past ! :-)

Who're you ?

If you do get the engine running well, replace all of the old fuel lines on the rail and the injectors before too much driving. I smelled gasoline on mine one day while driving and when I opened the hood a tiny stream of gasoline shot by me on to the sidewalk. They dry out and crack lengthwise. The small stuff will eat up a lot of your time but it's worth it once you're done.

Here is a way to test the function of the injectors separately from the ECU. With the ECU connector removed from the ECU, turn the key on. Then short the pins in the ECU connector from the injectors to ground with a quick tap. Each tap should produce a click frm the relevant injector. You'll need a quiet garage or a friend in the engine bay to hear them. Or a long wire.

I believe he mentioned 10 plus years.

That makes sense, I already testedt all the ECU pins and were reading correctly... The only thing left is the AFM which would also make sense why the injectors wouldnt firing. I tested each injector and they are functioning. I have stopped testing for the night because i broke a fuel line that was very old. will need to replace that before messing with the AFM. but i dont think im getting good signal from the AFM to the ecu. thank you for your help everyone.

How long has it been sitting? What's the back story?

I’ve mentioned it some many times in the past about replacing each and every connector on the EFI harness and cleaning each connection in that arena. You will be amazed at the corrosion that you find on each connector and the wire itself. I had to shorten some wire by over an inch before I could find wiring that was suitable to crimp/solder.

The engine can run off puddled fuel in the intake manifold. If the injectors were opening the engine would continue to run. cgcheen's suggestion about testing with a 9 volt battery was a good one. You can run separate jumper wires if you don't have an EV1 connector. With a 9 volt alkaline battery you don't have to worry about melting wires if you accidentally short them. You'll hear a click when you connect the 9 volts, if they're opening. Also, with 9 volts you can leave the voltage connected while you tap them. You'll have the solenoid pulling them open if you can get them to break loose. Pin 1 at the ECU is the ignition signal that the ECU uses to monitor engine RPM. It's connected to the negative terminal of the coil. It should read battery voltage with the key on. But it also needs a certain type of voltage pulse. There are things that can screw it up. You're making great progress.

I almost made a comment about AI. It's basically a better Google search. But that's about it.

I am reading through the FSM and all the materials trying to track down what i can find. Using AI is extremely helpfull as it walkthrough alot of troubleshooting and ruling things out. Right now i believe ive rules out the fuel system, the injectors are all functioning and sensors because its stopping after a running for ~9 seconds regardless of its tempature, hot or cold. The last thing for the ECU troubleshooting is the Tachometer. I am getting a signal from the coil at the tach, but i dont know if the ECU is getting that signal. That would explain after the ignition start sequence it doesnt see any RPM and doesnt tell the injectors to fire causing the engine to stop quickly every time. I am trying to find a pin that the ECU would recieve this information but cant find one.

I understand that, AI is a smorgasbord of articles massaged into one. He mentioned he was searching AI. The reason why I asked the question.

Yarb, the 1980 EFI book is the official Nissan electrical troubleshooting manual. It's basically the FSMs stripped down to the bare essentials and combined in to easy to use charts and instructions.

The most reliable source is the FSM that can be downloaded on this site

So what do you recommend? Keeping the 1.5 ohms pertronix and 1.5 ballast resistor i the circuit?