90 Maita will crank but won't start

'90 Miata w/ 60M. Problem: eng cranks but will not start. Car ran great
prior to problem and passed smog test. Problem started to surface as the
car became harder and harder to start due to "no spark" each time.
NO "CHECK ENGINE" light ever came on when the car ran. Items already
replaced: Battery, spark plugs & wires,coil, cam pos sensor, ignitor, main
ign relay. Areas ck'd: "Check eng" dash light, all body grounds,all ECM
grounds, power from ign switch to ignitor, airflow meter ground. ** No
power to injectors or airflow meter when key is hot or when cranked.
"Check Eng" light does not come on prior to cranking or when key is
initially turned to accessory.
Can anyone help with suggestions or info on what additional electrical
test to run or how to find a more comprehensive electrical manual.
Anything at all would be greatly appreciated.

Sounds like your initial statement of "no spark" is no longer true.
If you are sure there is no power to the injectors... have a look at the
'fuel injector' fuse(30A) in the main fuse box, the 'engine' fuse(15A) and
the 'main relay'. From what I see in the schematics in the Haynes manual,
the 'engine' fuse is hot in run or start, this picks the 'engine' relay,
which passes power from the always hot 'fuel injector' fuse to the
injectors.

Pete

"darylDJ" > wrote in message
lkaboutautos.com...
> '90 Miata w/ 60M. Problem: eng cranks but will not start. Car ran great
> prior to problem and passed smog test. Problem started to surface as the
> car became harder and harder to start due to "no spark" each time.
> NO "CHECK ENGINE" light ever came on when the car ran. Items already
> replaced: Battery, spark plugs & wires,coil, cam pos sensor, ignitor, main
> ign relay. Areas ck'd: "Check eng" dash light, all body grounds,all ECM
> grounds, power from ign switch to ignitor, airflow meter ground. ** No
> power to injectors or airflow meter when key is hot or when cranked.
> "Check Eng" light does not come on prior to cranking or when key is
> initially turned to accessory.
> Can anyone help with suggestions or info on what additional electrical
> test to run or how to find a more comprehensive electrical manual.
> Anything at all would be greatly appreciated.
>

Might be the ignition switch. It has a lot of contacts, among the ones that
are still working are those that enable the starter. The ones that enable
the ignition, however, may be kaput.

Ken


"darylDJ" > wrote in message
lkaboutautos.com...
> '90 Miata w/ 60M. Problem: eng cranks but will not start. Car ran great
> prior to problem and passed smog test. Problem started to surface as the
> car became harder and harder to start due to "no spark" each time.
> NO "CHECK ENGINE" light ever came on when the car ran. Items already
> replaced: Battery, spark plugs & wires,coil, cam pos sensor, ignitor, main
> ign relay. Areas ck'd: "Check eng" dash light, all body grounds,all ECM
> grounds, power from ign switch to ignitor, airflow meter ground. ** No
> power to injectors or airflow meter when key is hot or when cranked.
> "Check Eng" light does not come on prior to cranking or when key is
> initially turned to accessory.
> Can anyone help with suggestions or info on what additional electrical
> test to run or how to find a more comprehensive electrical manual.
> Anything at all would be greatly appreciated.
>

darylDJ wrote:
> '90 Miata w/ 60M. Problem: eng cranks but will not start. Car ran great
> prior to problem and passed smog test. Problem started to surface as the
> car became harder and harder to start due to "no spark" each time.
No, if there is no spark, it will not start. How did you check for
spark? Are you aware that the timing belt also controls the spark? I'd
take a look and see if my valves are opening and closing to see if the
belt is still functional. Granted, 60K miles is replacement time and
they will generally go well over that, age does have an impact. It may
have been starting to fray, allowed the timing to jump and then quit
altogether. It's a simple look see inside the oil filler hole to see if
the cams are turning. If not, needs nothing more than a timing belt.
Electronics are not an issue on the Miata (it's not Lucas electrics
after all and you've already replaced the whole system (with the
exception of the fuel pump which is where I would look after checking
the timing belt).

Tom
92 Red (gone but not forgotten)
05 Vette (red, but of course)


> NO "CHECK ENGINE" light ever came on when the car ran. Items already
> replaced: Battery, spark plugs & wires,coil, cam pos sensor, ignitor, main
> ign relay. Areas ck'd: "Check eng" dash light, all body grounds,all ECM
> grounds, power from ign switch to ignitor, airflow meter ground. ** No
> power to injectors or airflow meter when key is hot or when cranked.
> "Check Eng" light does not come on prior to cranking or when key is
> initially turned to accessory.
> Can anyone help with suggestions or info on what additional electrical
> test to run or how to find a more comprehensive electrical manual.
> Anything at all would be greatly appreciated.
>