Thread: Another 'no start' thread...sorta...

Changed the coil pack to the one from the old motor. fired up and stays running...runs fine. Up to temp. Nice when you have spare parts sitting there to swap out on the spot. thanks for the tips and direction to look. a few minor details to finish tomorrow night and I'll be topless motoring once again. Joe

Sounds like a fuel pump issue to me. I'd try here - http://www.miata.net/garage/fuelpumpdiag.html to see if that will identify the problem. I suspect you'll find the answer in these diagnostics....

I'd almost guarantee it's a fuel pump issue... Not that the pump is bad, but the ECU isn't keeping it on. When you turn the key off and on, the fuel pump runs for a second to pressure up, and "prime" so the car will start. BUT if the ECU doesn't see the signal that the car is running, it won't keep the pump on. This is to prevent the pump from dumping a bunch of fuel on a fire or something if the car...

If you are still using the Circuit Opening Relay (by which I mean if it is still in the fuel pump power circuit), I would expect this problem. The 1990 - 1993 Miatas use that component to provide power to the fuel pump. It has two coils. Coil #1 connects +12 volts to the fuel pump when the ignition key is in the START position. So fuel pressure will come up and the engine will run for a couple of seconds on that. But when the key drops back to...

This is a longshot, but do you have an aftermarket alarm system with an immobilzer? NAs didn't come from the factory with immobilizers, but what you describe is exactly what happens in an NB if you try to start the car without a key that the ECU has been programmed to accept.