[AlexE]

Hello,

Im helping my friend who bought NA 1.6/90HP (EU spec) with engine not running. We have both spent some time, found some problems but stuck a little - so help would be appreciated

So far we found/did:

• car hasnt been driven much in general, has only around 60k km, dont know how long it was waiting being broken
• engine started for a while with some "Plak" (fuel spray, dont know how you call it) sprayed into intake. So engine seems to be mechanically more or less ok
• fuel pump was completely dead, whole assembly rusty etc. We have replaced whole assembly (from NB/NBFL cant remember), also added some fuel to tank. Fuel pump was still not working because next issue

- MAIN relay is not energized when ignition ON. Relay is ok, GND on coil is ok but no +12V on B/W wire, see attached picture

this leads to 15A fuse "engine" blown but no - fuse is ok, there is +12V on one side (L/F wire) in fuse compartment. So fault is probably after 15A fuse.

my 1st question - where is X10 connector?? cant find it

I was also looking for non original wiring - nothing suspicious near both fuse boxes or engine harness

- i tried to feed +12V to B/W wire near Main relay. Relay starts to work, fuel pump also runs (checked Circuit Opening / Fuel Pump relay in a meantime - ok). Fuel is present on Fuel rail (dont know pressure), injectors seem to get pulses. But engine does not start.

We got stuck in this situation, battery died, it became late so we left

my 2nd question - what now? why it is not starting? what to check?

Car is 50km from me so I would like to prepare for second attempt as good as possible

 

[Zed.]

you can bypass the fuel-pump relay and connect +12v to the pump wiring input to test the system, if the relay has no 'trigger' from the ecu then its worth looking at the ecu as it can be wet or have corroded wiring causing issues

my 2nd question - what now? why it is not starting? what to check?

possibly a stupid question but...

have you checked for ecu fault codes??

Retrieving Engine Fault Codes for MX5 1989-2002

How to Retrieve and Translate Engine Fault Codes using the Diagnostic Connector on Mk1 (NA) & Mk2 (NB) MX5 Miata Eunos 1989 to 2002 Models.

mx5diy.blogspot.com

^^ always worth checking and also cheap

Rich.

 

[Martin Y]

I don't know where that X-10 connector is but if you have more of those diagrams they have drawings showing the layout of each connector and the wire colours on each pin. That might make it easier to spot. (The partial diagrams I have are for the Japanese spec Roadster and its X-10 is completely unrelated - something in the power windows.)

Is it possible the car has an aftermarket immobiliser fitted? That might well interrupt that B/W wire.

 

[AlexE]

so far I havent found any aftermarket immo or any suspicious non-oem wires

bypassing fuel pump relay has no big (if any ;-) ) sense for me, as main relay is not energized. If I bypass main relay fuel pump works normally.

I admit, havent checked ECU fault codes, because I know this ecu is really simple and diagnostics is poor

ECU area wasnt flooded, contacts look perfect

other question - how to remove at least partially small fuse box under the dash?