stalling without warning
 

hi guys.
1990 Miata. runs fantastic then dies sometimes it will restart before I get to the curb; other times I have to wait a few mins.
so far I've only replaced the fuel filter, cleaned the ground connection near the brake cyl, and checked/cleaned the plug connections on the ecu and that cam sensor thing.
i'm thinking it's an electrical issue but i'm no expert.
I know that's not much to go on, and I haven't confirmed fuel pressure, but it doesn't sputter, it just dies as if you pulled the plug, then starts right back up.

I think it's electrical as well.

Check the ignition parts next. Also check the cable connections at the battery and the alternator.
A failing alternator can cause some strange things because of the severe voltage jumps.

where to start w/ ignition troubleshoot? when its running, it shows no symptoms.
I've googled and found ignition switch threads and cam sensor threads, ect. I don't wanna throw money at it (but I guess it would help narrow things down).
I will check connections on alt and battery terminals.

Is this OBD1, in other words is there a check or service engine light? Do the dash lights flicker go out or stay on? Dash lights meaing check oil, hot, brake on ect? Also does it have an electric fuel pump? You say restarts before it gets to the curb, does it restart immediatly?

hi thanks.
I just was watching it run in the garage.
the seatbelt light was lit as I wasn't in there while it idled.
the engine died and ALL lights on the dash stayed out for about ten seconds then all the idiot lights came on as if i'd just inserted the key.
it wont restart until these idiot lights come back on.

Ok, does it start right up after the lights go out, and do you turn the key to off before restarting? Is it electric fuel pump? Can you hear the pump run when it dies?

thank you Kevin.
it runs, dies. wont start.
ten, sometimes thirty, seconds later, the dash lights(idiot lights, indicators) come on and the car will start back up.

the car will not restart until these indicator lights come back on.

I haven't checked the fuel pump. I do not know if its mechanical or electric or the location but I assume the electric would be in or near the tank.
i'm hearing impaired but I will listen carefully while turning the key for an electric pump as per your suggestion.

I was leaning toward an electrical issue because the engine never sputters it starts right up and idles like new. performs flawlessly, then dies instantly as if you pulled the plug on the ignition.
never seems fuel starved.
but I will check it. I was thinking I should get a fuel pressure gauge but I don't have one right now.

Here is one thing you can do that costs you time but no $$$$.
Remove the battery and the alternator and take them to a parts store for free testing.
If they check out fine you at least eliminated them from the list of usual suspects.

I seem to remember that the early Miatas had issues with the MAF sensor. hmmmm I found it:http://www.miata.net/garage/afm_fix.html

What i am trying to determine is it fuel or other related. If after the time you try to restart it i.e. turn the key to crank/start it, is there a 2-3 second delay before it starts?

I make distinction between checking and replacing. The Haynes manual and Youtube provide ample information on how to check just about anything.
How do the sparkplugs look?
Disconnect inspect and reconnect all wire harnesses. Sometimes it removes corrosion and thus makes better contact. You can take off, clean and remount anything. Sometimes you need a new gasket if you do that.

Sure, that's not a direct way to find the problem but a '90 Miata can stand some cleaning, right?

yes. and I believe its something simple like that. I think I've read where someone had a similar issue and found the ignition switch dirty or corroded?
i'll get some contact cleaner and have at those wire harnesses.
I've obtained a service manual; so now I have something to read.

well, a mechanic friend of my roommate has told us that it could be dashpot on the throttlebody/throttle position valve?
I haven't priced this part or even located it on the engine yet; just seeing if anyone has an opinion on this based on my symptoms:
stalling without warning at any speed.
dash indicators, idiot lights don't come back on for 30 seconds.
car wont restart until the indicators come back on.
no smoke hesitation or sputter. very crisp throttle.
stalls unexpectedly.

Is this the post that you state with key on, you hear a click, and it starts? Iknow about vacuum controlled dashpot on a carb'ed engine, but not on your vehicle. i will state this, it is electric I am sure, dashpot kicks the throttle off the minimum. Why you are having idiot lights going off is something (if related) I don't know.

What if the ignition switch in the column is going out? I think it could cause these symptoms.

I would have to agree.

I think I wanna have a look at the ignition switch.
i'll search youtube for a vid.
anyone have a link where I can learn about disassembly before I start?
is this a napa part or a dealership part?
thanks guys!

I'd call NAPA first.

There are tons of videos. You may also google for images.

we bought a new ignition switch from ebay autozone/ napa couldn't get it for us and advance wanted 400bucks! ebay was 80bucks. installed it but still have the same problem. I think the plug itself is going bad.

indeed it was the plug on the ignition switch. hasn't stalled for days now.
I disassembled the switch, it was pitted. I replaced it but still had a stal;ling problem, but not as bad. then I cleaned the plug w/ contact cleaner and a qtip. it didn't look bad but I was there so might as well clean that too....turned out to be the problem...I guess a little dirt was causing a little resistance.

You need to do this:

http://i1049.photobucket.com/albums/...2/SAM_0800.jpg

GET YOUR ZOOM ZOOM BACK!

Excellent! Thanks for the feedback!