Zatarra

With the help of ChatGPT and the FSM, I have been trying to track down this crank/no start issue. Here is our summary. I have a 1977 Datsun 280Z that is currently cranking normally but will not start. I have been working through the **1977 Factory Service Manual EFI no-start tests** systematically and would appreciate some input, particularly on the EFI double relay and FSM test 1-(7). ### Current setup The engine was recently rebuilt and was running well afterward. It has: * Rebuilt L28 * Stock cam * New timing chain/components * Rebuilt/machined block and head * **280ZX electronic distributor conversion** * Bosch/Nissan E12-series ignition module * New **NGK 48776 ignition coil** * New cap and rotor * Pro Tunerz fuel rail * Standard Motor Products **FJ707 injectors** * Cold-start injector/valve deleted * Intellitronix digital gauges/tach * Original fusible-link block replaced with a **Mini-ANL fuse block** * Original Bosch EFI double relay: **0 332 514 120** The engine ran well after the rebuild and I successfully set the ignition timing while it was running. The distributor has **not been moved since**. ### How the no-start began The car ran normally but I could not work on it here and there so I had it on a battery tender, I replaced the battery, and after that it would crank but would not restart. The grounds at the battery are **hard-wired and were not disconnected during the battery replacement**. I also checked the separate EFI positive feed/fusible link at the positive battery terminal. Continuity through that circuit and through/bypassing that fusible link was good. ### Current symptoms Fuel: * Fuel pump runs while cranking * Approximately **40 psi fuel pressure while cranking** * Pressure bleeds down gradually afterward * Noid light **pulses at the injector connector while cranking** * Injector connector has battery voltage * Plugs remain **dry** * No raw-fuel smell from exhaust * I have not been able to clearly hear the injectors clicking while cranking with a screwdriver I measured two injectors directly: * Injector #4: **3.1 Ω** * Injector #5: **3.1 Ω** The factory dropping resistors are still present. Ignition: * Inline spark tester flashes consistently * Spark appears **orange/red rather than strong blue/white** * New NGK 48776 coil did **not** change the spark color * Timing light flashes steadily on #1 while cranking * Timing mark is approximately **10° BTDC** * Digital tach shows activity during cranking Battery voltage during cranking has been around **11.25 V**, so cranking voltage appears healthy. I also temporarily added a heavy **body/fender-to-intake-manifold ground strap**. It made **no difference** to the no-start or dry-plug condition. --- ## FSM EFI testing completed I followed the FSM “Engine Will Not Start” tests. ### Section 1 — continuity tests **1-(3) Air Flow Meter — PASS** At the 35-pin ECU connector: * 6 ↔ 8 = **182 Ω** * 7 ↔ 8 = **179.3 Ω** * 8 ↔ 9 = **103.5 Ω** **1-(5) Fuel pump contacts — PASS** 35-pin terminals 10 ↔ 20: * AFM flap closed = open * AFM flap opened = **56.6 Ω** **1-(6) Water temperature sensor circuit — PASS** The apparent failure here initially turned out to be meter range. * Pin 13 → water-temp harness = **0.8 Ω** * Ground side of water-temp harness → body = approximately **0.8–0.9 Ω** * Sensor itself = approximately **1848 Ω** * Pin 13 → body with sensor connected = approximately **1830 Ω** **1-(7) EFI/fuel-pump relay circuit — N.G. / CURRENT ISSUE** FSM calls for: **35-pin terminal 20 → body metal = continuity** Mine reads: **OPEN / `1`** I repeated this on the **200 Ω, 2000 Ω and higher ranges**. Following **Fig. EF-45 on FSM page EF-33**, I then isolated the circuit. Known-good results: * 35-pin terminal **20 → relay socket 86b = 0.7 Ω** * Relay socket **85 / wire 72 → body = 1.3 Ω** * ECU ground terminals: * 5 → body = **1.1 Ω** * 16 → body = **1.1 Ω** * 17 → body = **1.1 Ω** * 35 → body = **1.1 Ω** So wire 20 reaches 86b, and the 85/72 side reaches ground, but **terminal 20 still cannot see ground through the relay**. I then removed the relay and measured directly: **86b ↔ 85 = OPEN** * 200 Ω range = `1` * 2000 Ω range = `1` I have repeated this several times. That is where I am currently focused. **1-(8) Air regulator/fuel pump circuit — PASS** 35-pin terminal 34 → body: approximately **60–65 Ω**, repeatable using multiple body grounds. **1-(9) ECU ground circuit — PASS** * Pin 5 = **1.1 Ω** * Pin 16 = **1.1 Ω** * Pin 17 = **1.1 Ω** * Pin 35 = **1.1 Ω** --- ## EFI relay bench test The relay is the original-style Bosch **0 332 514 120** double relay. It actually **passes the normal FSM relay bench tests**. ### Main relay +86c / −85: * Relay clicks * 88z ↔ 88a = **0.7 Ω** * 88z ↔ 88b = **0.7 Ω** Reverse polarity, +85 / −86c: * No click, as specified ### Fuel-pump relay Unpowered: * 88d ↔ 88c = **0.7 Ω** * 86a ↔ 86 = **0.7 Ω** +86a / −85: * Relay clicks * 88y ↔ 88d = **0.9 Ω** Reverse polarity, +85 / −86a: * No click, as specified So the relay passes those factory bench tests, **but 86b ↔ 85 is completely open**, which also explains why FSM 1-(7), pin 20 → ground, fails. I have opened the relay previously and cleaned the contacts. Nothing obvious looked burned, but I now have it open again and am tracing the 86b circuit internally. --- ## Fig. EF-45 wiring checks I also checked the heavier injector/relay wiring shown in Fig. EF-45: * Circuit 31 = **1.1–1.2 Ω** * Circuit 43 = **1.1–1.2 Ω** * Circuit 56 = **1.1 Ω** * Circuit 70, including the separate positive-terminal fusible-link circuit = **1.1–1.2 Ω** All appear intact. --- ## Section 2 — voltage checks All with key ON: * 2-(1), ECU pin 1 = **12.4 V — PASS** * 2-(2), ECU pin 10 = **12.5 V — PASS** Injector/dropping resistor circuits: * Pin 14, cyl. 4 = **12.49 V** * Pin 15, cyl. 1 = **12.49 V** * Pin 30, cyl. 5 = **12.49 V** * Pin 31, cyl. 6 = **12.49 V** * Pin 32, cyl. 3 = **12.49 V** * Pin 33, cyl. 2 = **12.49 V** All six **PASS**. ### Section 3 With starter S terminal disconnected as instructed: * 3-(1), starter signal pin 4 in START = **12.3 V — PASS** * 3-(2), air regulator pin 34 in START = **12.16 V — PASS** * 3-(3), cold-start valve/thermotime switch = **N/A because cold-start system has been deleted** --- ### Where I am now The two things that still stand out are: **1. EFI relay / FSM 1-(7)** Pin 20 is supposed to have continuity to ground, but it does not. Wire 20 to 86b is good and 85/72 to ground is good. Directly across the relay, **86b ↔ 85 is open**, even though the relay passes the other FSM bench tests. **2. Weak-looking ignition spark** The engine has consistent spark and correct-looking cranking timing, but the spark remains **orange/red even with a new NGK coil**. I am also considering testing the 280ZX distributor pickup/E12 ignition module. The biggest mystery is still: **~40 psi fuel pressure + 12.49 V on all injector circuits + pulsing noid light, but plugs remain dry.** Has anyone seen a **Bosch 0 332 514 120** where the normal relay bench tests pass but the **86b-to-85 circuit is open**? And could a failure in that 86b branch account for more than just the pump not remaining on after START — specifically, could it contribute to the injectors not actually delivering fuel while cranking? I can order a new relay from FCP Euro, no problem. Just getting others opinion and guidance. I’m also interested in any 280Z/280ZX experiences where a **persistent orange/red spark with an E12 electronic distributor** turned out to be the ignition module or distributor pickup. Thank you.

Sounds like a plan. I'll remove the valve cover and lightly oil, I'll take off the wire from the ignition coil, remove all spark plugs and crank it a few times before reassembling. I was able to rebuild the engine outside of the typical machine shop work because of detailed instructions all over the internet and manuals. I just had to be really sure on this process as well as no detail is too small. Thank you!

I see a few posts regarding fixing the original heater control valves. Unfortunately I don't have that option anymore but has anyone tried the electronic heater control valves? I see two options, a bypass version and a standard version but I don't know which route to go if anyone would be better for the engine. Considering the strong feelings about blocking off the coolant lines whenever someone deletes the heater core. The standard version would just prevent the flow when set to cold (similar to OEM) vs the bypass version is supposed to route the coolant back when set to cold. https://autoacsolutions.com/products/heater-control-valves/electronic-bypass-heater-control-valve-with-rotary-switch-for-datsun-nissan-200sx-240z-260z-280z-280zx-310-510-720-pickup-4runner-maxima-pathfinder-sentra/ https://tomsoffroad.com/parts/66-77-ford-bronco-electronic-heater-control-valve?gclid=Cj0KCQjwtJKqBhCaARIsAN_yS_nslsHrg8iEKvyYFpBPYYlFkKeowtIuIh6l53LFIB1RRR2VVM65RPsaAsd3EALw_wcB What are your thoughts?

Greetings. I rebuilt my 77' 280z a year ago and drove it around for a few miles just to make sure everything was running fairly smooth. The entire engine was taken apart with new bearings, rings, head bolts, etc. I live in California and did not feel like dealing with the smog just yet so I took out the dash and restored it as well as restoring the gauges with Intellitronix inserts. Now I am ready to restart it, should I be fine just to crank it right up or should I follow something like atlanticz's steps to put it back in service? http://www.atlanticz.ca/zclub/techtips/storing/index.html "Putting Back in Service Remove plugs and crank engine at starter to flow oil through engine until a good and steady oil pressure. This will take 45 seconds or so. Install plugs and away you go. Check for leaks and proper vehicle functioning. Replace all fluids" What does it mean by "crank engine at starter"? Note, it was only driven about 10 miles after the rebuild, assembly lube used where appropriate but has not had an oil change since. Thank you in advance!

Thank you all for your feedback. I am going to move forward without the shims, the thinnest I could find are .015 but only .012 has been taken off. This coincides with the two resources that ask for shims only when .02 or more has been removed. I'll definitely pay attention to the chain tensioner once I put it back together too, thank you!

I have a pair of Porsche seats waiting to be installed, it will require a custom bracket but I've seen it done. https://www.pro-touring.com/threads/82024-PT-datsun-240z @SoCalJim Beautifully done!