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Discussion Starter #1 (Edited)
While driving / cruising (70mph) on a straight (15miles) road, my car shut-off.
I had enough momentum to carry the car on the shoulder of the interstate. I had no warning or any symptoms, just out of the blue the car died.

While on the side of the rod,using my trunk tool box ( a must have) i was able to check the following:

Fuel pressure 32psi
Spark ok on all four plugs
fuse box ok
Battery voltage 12.4V
Fuel pump both running ok
Relays (main and Drive seem to work)

I even walked to the near gas station an purchased an" engine start fluid" but the car would not start when i sprayed the fluid in the intake plenum.

I am truly out of options, could anyone have better ideas?? I am tempted to think that the CPU is bad but I wish i could chake it before buying one. Inputs are really really appreciated.

Car is an 1985 L-Jetronic Alfa Spider

Thank you
 

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If you've got fuel pressure and fire, that leaves air.

Any reason to believe a ground wire didn't suddenly snap, particularly the ones that go on the cam cover under the AAV?

How's the fuse back by the ECU? (pumps running indicate that there's at least some semblance of juice getting through and that the coil is sending it's signal to the big relay, but is it a really great connection?)

Did you look for goofy stuff like the harness coming unplugged from the AFM or a loose battery terminal?
 

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The fuses in our spiders can look OK but still be problematic. Try installing new ones even if they don't look 'blown'.

Are you sure there is spark? If there is, it should have at least made a kick on starting fluid (even if the injectors are not squirting).

Check carefully for an intake air leak. All air entering the engine must pass through the AFM (Air Flow Meter - on top of the air filter). If the main duct is knocked loose or one of the hoses cracks/falls off then the AFM can't tell the computer the engine is drawing in air - thus no/improper fuel injection. Make sure the harness connector on the AFM is secure and that none of the small spade connectors inside are bent/damaged.

Check the flywheel sensors. Make sure they are still in place (I've read reports of them falling out due to stripped threads) and that they measure between 800-1250 ohms (full instructions in the L-jet page in my signature block).

Make sure the distributor hasn't moved. With #1 at TDC on compression the rotor should be pointing at the location of the #1 spark plug wire in the cap. Make sure there isn't a fault in the rotor or cap.
 

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Spark ok on all four plugs

I even walked to the near gas station an purchased an" engine start fluid" but the car would not start when i sprayed the fluid in the intake plenum.
Very confused! Engine starting fluid would make a fire no matter what if you had spark. Even if the ecu wasn't spraying the injectors, no matter what, starting fluid and spark would make an engine run unless you did not have ANY compression. I use starting fluid to eliminate fuel problems in troubleshooting, if it didn't start while using starting fluid, I'd wonder how you knew you are getting spark. Even if the timing was off, you get a considerable "Popping" noise from using starting fluid, sometimes, a fire ball through the plenum if you used too much or the timing was too far advanced. Again, how do you know you got spark? Even if your cam chains broke, more than likely one valve would've been open to allow the ether vapor in, that would've shot out the plenum for sure, very confused by your situation.
 

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Inertia/Safety box?

Hmmmm... ok, not havinh half the smarts most others have in this forum, I have only an experience to rely on... my '84 did something similar... was cruising down the road (only at 45 though :) )... next thing I knew... done, just shutdown... would crank like all get out... same thing tried starting fluid etc... just would not fire up... crank like the dickens though... ok, all the basics, air etc... long story short (too late?)...

I have an "Inertia Box" near the top middle of the firewall inside the engine compartment... mine was a little bigger than half the size of a pack of smokes... I guess this thing is designed so that if you have an accident... it would shut things down... anyways... it is encased in a black rubber casing... top of the casing has a reset button... well, hitting reset did nothing... again, long story short... I cut both wires (in and out) and spliced together just to try it... lo and behold, she fired right up... yes, for now I no longer have the inertia box, and will replace sometime "down the road". Again, this was real simple and you could probably just use a jumper to bypass this little unit and see what happens... took all of 5 minutes to bypass... once I did, success.

Bottom line, this "box" failed... even reset did not good... bypassed, all is ok.

Might be worth looking into, assuming you also have this.
 

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One more quick thing to add... this link (below) can at least show you what my Inertia Switch looked like, neat photo. Again, not even sure if you car has one, or if there are better ways to test them out. Of course there are probably tons of things that can cause this issue... again, in at least one case for me (and for others as I searched the BB), it was this switch. Good luck.

The link is:

http://alfabb.com/bb/forums/showthread.php?t=26920&highlight=inertia
 

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My sons Miata has a problem with ignition wires, it seems they go bad after the spark plugs open up. I have checked his plugs and found them completely open. are you sure you have spark thru the plugs? nice fat blue sparks?
cliff
 

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@ WIP, but of general use to the thread:

IF it's determined that the inertia switch is the issue and IF there is a large tachymeteric relay back by the ECU, then bypassing/removing the intertia switch isn't a safety issue and can be left alone unless you're after a specific level of originality.

The way the tachy relay works is via pulses from the ignition coil, and once activated, (engine cranking & plugs firing), it causes the fuel pumps to run and sends a signal to the injector relay. (the smaller one right in that same area)

If you get into an accident and the engine stalls (when doesn't it?) then the coil signal stops and the tachy relay shuts down cutting off the pumps and injectors in one fell swoop thus doing the exact same thing that the inertia switch was designed to do.

Basically the inertia switch is one of those department of redundancy, redundancy department carryovers from the SPICA era that was later eliminated alltogether about halfay through the S3 run. (factory bypass consisted of just plugging the two underhood switch wires where the switch would have been together)
 
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