Are you still chasing info regards factory EFI L18? I have all the info you could need. I have built a few of these, starting back in 1987. My son still drives one of the 180Bs I built with the factory EFI added onto an L20B block. I still have most of the bits needed to put one together: manifold, ECU, wiring loom, wiring diagrams, factory manual, and …

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Its long since i logged in here


unlimitedpower

This is marvelous! How did the project go. Please share

AlanDatsomefun,

I am still chasing that info. Wiring diagrams and factory manual would be nice.
Have you done any mods on either of them?

I didn't have OEM EFI relay and fuel pump relay, so figured this out from scratch using factory wiring diagram as a guide. I didn't have the OEM air cleaner, but was able to get the correct air flow meter. The EFI is much the same as the original installation and runs on an L20B with a mild street cam. I'm guessing that it makes about 125HP. My son has the car, but I have access to all the technical info. I can help you with that.
The person who commented that if you want better performance then use an aftermarket engine management system (MoTec, Haltech or whatever) is right, but this L-jetronic works fine albeit not a high performance setup. I have since built a stroked naturally aspirated L18 with custom internals, MoTec and custom manifold: it makes 200Hp, but it has cost me a small fortune. … pays you money … takes your choice!

Let me know how I can help. I will do what I can though I cannot guarantee an immediate response every time. I'll do what I can.

As I gather the info together I will post it on this forum.

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AlanDatsomefun
thank you for this information. One thing I couldn't make work is the fuel pump to run at the ignition "ON" position and i had to connect it 'direct'.

I would wish to have the L-Jetronics running (the car has been under a slow restore) then I am thinking of looking into a simple after market engine management but using the plenum. The car is intended to be a daily drive.

I would wish to have a look at what you came up with in place of the OEM EFi relay

Thank you

For safety reasons power is provided to the fuel pump during cranking (ignition "ON" and power to the starter motor "START") and when the ignition is "ON", and engine is running normally. In the "engine running" mode there must be oil pressure AND output from the alternator (alternator turning with ignition on). If there is a problem with either, a warning light will be displayed on the dashboard. If there is a problem with both, power will not be supplied to the fuel pump and engine will not run.
Without the original EFI and Fuel Pump relays, you will need several relays (typically three).
I've posted the wiring diagram I built for my car which has R31 ignition switch and I am running a MoTeC electronic control unit, but the fundamental wiring for relays will be the same. In this diagram, as an additional precaution, power is provided to the ECU only when you want the engine to start and run. I have shown relay pin numbers corresponding to the functions specified by the Bosch (DIN) naming scheme. I can post a copy of the (simpler) wiring diagram I used for my first EFI installation. From memory it used very common types of relay (5-pin with contacts normally open and 5-pin changeover types). Unfortunately I do not have it at hand and it could take a few days to find.
Please see Bosch L-Jetronic for Datsun wiring diagram for early to mid 80s Datsun (either 4 or 6 cylinder). This shows an oxygen sensor in circuit, but I've never seen one fitted. You will find that pins 16 and 31 are not connected to the electronic control unit.
Alan

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AlanDatsomefun.

Thank you

Let me look at the schematics and revert.

I have located an OEM Nissan manual for this EFI - if you want, contact me by private message.

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An easy solution to your fuel pump relay issue may be to use an LPG Safety switch.
These are used in LPG installations to switch power to the LPG lockoffs (valves in the LPG supply line with solenoids that open the valves only when power is supplied). Typically they wire in to the oil pressure switch and only open for 3 seconds without oil pressure. That's enough to get you started and the idea is it shuts off the LPG flow if the engine stops, even if the ignition is still on.
You can get them at any LPG component supplier (or even a wrecker) and they're cheap, reliable, easy to install and wire up.
The Safety Switch would not supply power directly to the fuel pump (the solenoids it's designed to switch usually draw 1amp or less and a petrol pump needs more) but switch a single appropriate sized relay that supplies fuel pump power. A 30amp 4 pin relay like a Hella 3078 should be fine. Remember you'll need a fuse in the circuit, too.

Hope this is useful for you. Cheers!

Regardless of how you might do it, SAFETY FIRST: ensure it will function in each of the required modes before wiring it up, wire it up and comprehensively test before installing in the car. It is critical to have protection against something going wrong. Nothing worse than having a fuel pump supplying fuel at 35psi when the engine has stopped and there is a leak onto a hot exhaust!
The best, safest and most reliable way is to replicate the relay functions in the Bosch L-Jetronic diagram attached (which comes from the Nissan EFI Manual). If you are not confident to do this yourself, any capable auto electrician should be able to wire up a pack of automotive relays, e.g.: 3x 4-pin relays and one 5-pin changeover type to provide the necessary functions.

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