MX5 Miata Tech Forum

My 99 NB1 with 105K has a weird problem. After a hot run on a hot day, and after 20 min or so of cool down, it won't start. It cranks and cranks but no go. Leave it an hour or so and then it will start normally, though often with a backfire through the intake. No codes have shown. We've changed out cam and crank position sensors and checked fuel pressure. Nothing changes. Four techs and a Japanese car specialist can't figure it out. Any ideas greatly appreciated!



Edited 1 time(s). Last edit at 2024-10-25 05:39 PM by Jaybird248.

After chasing a bunch of electronic solutions to no avail, the answer was the simple replacement of the fuel pump and under body fuel filter. (The pump was probably 26 years old and getting senile.) In any case, the car now starts like a little champ.

One of the techs did do a fuel pressure test but while the car was running, when it was making its own vacuum drawing fuel to the engine. The pump only works for the start, then a relay shuts power off when fuel is flowing.

Along the way, we also replaced the battery and coil, which also helps.

So thanks for your ideas. Hope this helps if you face the same or a similar issue.

Glad you got it figured out, thanks for the update!

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