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Old 03-18-2009, 07:53 PM   #1
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Default No start / no fuel - help please

1995 Miata
RX7 550 injectors - newly cleaned & tested

Removed & replaced my engine/tranny to install a turbo setup. It won't fire up because the injectors aren't pulsing. Tried the stock ecu & my MSPNP, with the same results from both.

I verified spark by pulling the #1 wire and plug and observed spark while cranking. Did the same for #2, so both coils are definitely firing.

Fuel is getting to the rail, and the lines aren't reversed.

The MSPNP primes the pump at key on, stock ecu doesn't, but honestly I don't know if it's supposed to. With the stock ecu, jumpering FP to GND in the diag box activates the pump at key ON, but the injectors still don't fire while cranking.

I went as far as pulling the fuel rail, and watching it while cranking, and there injectors aren't firing at all.

All fuses in engine bay and under the dash check ok, and I swapped the fuel injection relay with the fan relay, but there was no change in symptoms.

The check engine light is on, which I've never had before, but when I jumper TEN to GND, and turn the key to ON, the light goes out after about 5 seconds, and does not flash any codes.

A few days ago when I put the engine back in, I pulled the fuel injection relay and cranked the car to prime the oil feed to the turbo and didn't see the check engine light, so it's strange that it's on now.

So what signal is the ecu not seeing that's keeping these damn injectors from firing?

Should I data log the MSPNP while cranking, will that help with troubleshooting?

I'm in a time cruunch with this car, I've got until next Wednesday night to get it running for a road trip, and I'm away this weekend.

Thanks in advance for any help.
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Old 03-18-2009, 08:12 PM   #2
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First thing first with megasquirt. Reflash the firmware and reload the MSQ.
Be aware of flashing precautions, unplug your coils before flashing the firmware and don't plug them back in until you have the MSQ loaded for the first time.

That and make sure your injector harness ground wire is connected/clean.
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Old 09-24-2009, 04:48 PM   #3
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6 months later and it's almost fixed. I had it trailered up to Kessler Engineering, and he had it running the first day he looked at it. Turns out my 550's were stuck closed. The car runs fine on the stock injectors & either ecu, so that's encouraging.

The injectors are back at Injector Rehab for a re-do and if all goes well, I'll be up at Kessler's on Tuesday or Wednesday to tune the car on his Dynapack, and drive it back home.

I'm pretty surprised the injectors stuck closed like that. Injector Rehab's site says not to let them sit for more than 30 days. Mine were on the shelf in ziplock bags for 12 months after being cleaned, but I've had injectors sit for longer than that and have never had a problem. :shrug:

The last time I drove the car was probably 9 months ago, and I've never even heard it run under it's own power with boost. I've got my fingers crossed that all the other work I did is up to par, and hopefully the trip back home will be uneventful. I wish I had done this a few months ago, because I'm attending an HPDE at Watkins Glen next Saturday, and would love to bring the Miata instead of my SE-R, but I'm not going to chance it right out of the box.

Wish me luck!

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