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I think my fuel regulator is busted. My ECU logs fuel pressure and noticed today that my fuel pressure was at 370kPa with the fuel pump running but the engine not running.

I reviewed some old logs and it used to be 330kPa for the same scenario.

I'd like to know what another NB8A MX-5 runs at as a comparison, does anyone with an NB8A log their fuel pressure or have a gauge connected?

Alternatively if you have access to an Australian or Japanese service manual that states the pressures the fuel rail should be, that would be even better!

I have a "Miata" service manual but the US spec NB8A has a deadhead system running a higher base pressure.

Cheers

43.5psi ??? 3 bar ???

That's using a known-good gauge and you are definitely sure you aren't running an NA reg or anything like that?

Out of interest can you note any numbers written on your reg and post them?

Pretty sure all none turbo BP engines 90-00 are 43.5psi.

You are in Brisbane yeah? Do you mind if I temporarily hook a pressure transducer to your feed line?

Timk I can look at my logs if it would help, it is a NB engine.

Thanks for the offer, does it have an NB8A fuel pressure regulator?

Cheers

No aftermarket pressure regulator. From memory it has been very stable.

Out of interest what base pressure do you have yours set at?

I'll check my logs when I finish at work ( a few hours)

From Jap Nats fuel pressure was 43.5 psi from start to finish.

That's relative to the intake manifold pressure I assume? Not absolute pressure.

The sensor is gauge pressure (Honeywell MLH 0-100 PSIG.C1P).

Okay cool thanks, I assume the reference line isn't connected to the regulator then?

Sorry for all the questions but I want to get this sorted!