bliffle

Driving the SE, suddenly the engine died, all warning lights came on, tachometer needle jumped all the way to end, buzzer sounded. It'll restart and idle OK, but die again if RPMs go over 2000 or a few seconds elapse.

Figured maybe alternator since warning lights came on while driving, so I disconnected the field and armature connections but no change.

Checked voltages with voltmeter and all battery connections good, full voltage at fusible links, (gotta check underdash fusebox later today). Checked coils voltages, seem OK until engine dies.

I'll pull alternator and check it at autostore, but probably not alt since battery voltage goes up when engine running.

Maybe it's time to overhaul the ignition switch.

Maybe I better check the ECU, too.

Could be some fuel problem, too, since it runs a few secs right after starting. Is there an easy way to check the fuel pump and the fuel flow?

Gas tank is 3/4 full. AC was on and pumping because the day was so hot. Cockpit fan going full speed.

Any other ideas besides alt, ignition switch, fuel pump, fusebox?

j9fd3s

iTrader: (3)

not really, it does sound like some sort of voltage problem

Rx-7Doctor

iTrader: (13)

Not charging problem. If it was the battery would be dead and you would not be able to restart.

Could be trailing ignitor is starting to fail.

Need to actually determine if you are losing fuel or ignition when this problem occurs.

bliffle

I'll test more after sundown. Maybe it'll be cooler then.

If trailing ignitor fails won't it run on just leading ignitor? Or does fuel pump run off trailing ignitor.

Rx-7Doctor

iTrader: (13)

Fuel pump circuit runs through trailing ignitor so she would just stop running.

I'd check the connections at the trailing ignitor and if they are good I would just swap out ignitors if you have a spare one.

Also when was the distributor rotor last changed?

bliffle

I've got plenty of spare ignitors. I checked distributor cap and rotor and they both look good.

Rx-7Doctor

iTrader: (13)

Can't tell by looking at the distributor rotor if it is grounding out or not. I would recommend the swap out of the ignitor then see if that cures the problem. Carry a spare distributor rotor in the car with you. If it acts up after you swap the ignitor out then swap in the rotor this way you will know what one caused the issue. :-)

bliffle

I have a spare ignitor, rotor and cap in the car always. Doesn't everyone?

Rx Seven

iTrader: (12)

Did you get a chance to check your fuses yet? I had a friend who had a similar problem and I believe it was either one of his fuses being out or a loose wire.

bliffle

Didn't get a chance to check it because the ventilation fan on my boinger sedan went out while driving around in this heat wave. Had to fix that first.

bliffle

I replaced dist cap and rotor with no change, Also checked ignitors. I devised my own impromptu hackers ignitor tester as follows:

materials:
- 12v. test light (old taillight bulb) terminated with two alligator clips
-two 24" wires colored yellow and green with alligator clips at each end
-a plastic Quick Grip with a quick release

procedure:
-use Quick Grip to clamp ignitor to negative battery connector with metal ground surface in contact with cable connector and other connectors accessible.
-attach one end of testlight to binder bolt of pos terminal
-attach other end of testlight to spade lug, top of "T", on ignitor
-attach green (say) wire alligator clip to pos terminal binder bolt
-attach other end of green wire to bottom of "T" spade lug on ignitor
-attach yellow wire alligator clip to pos terminal binder bolt
-touch other end of yellow wire to outermost of the two terminals in recess
-testlight should light if ignitor is good
-detach the 3 wires from pos terminal first (testlight, yellow, green)

I tested 10 ignitors in 10 minutes with this rig.

I've already tested all the fusible links on the shock piller.

Now I have to test the fuses and the two fusible links in the steering column.

The behaviour of the SE is quite simple at this time:
-upon turning the key the engine starts instantly
-idles smoothly
-after 10-12 seconds engine dies (as if ignition was cut) and warning lights come on.

All other electrics work, as near as I can tell.

bliffle

Fuses are all OK. But I can't locate those two fusible links that are supposed to be along the steering column. Anyone know how to identify them?

Tested it again: it starts easily, runs 10-12 seconds and stops dead, like the ignition is cut (indeed, there is no voltage at the coils when it dies). I can't imagine how it could be a fuel problem: fuel problems die with a protest.

It's as if there's a starting circuit that gets it running for 10 secs then another circuit is supposed to take over.

Maybe it's the ECU. I rounded up a document about testing the ECU. I'll study it tonight.

Maybe I'll renew my ALLDATA membership.

RXnos1200

iTrader: (24)

hook up a lead wire to the positive of the coil directly from the battery + and fire it up. See if it stays running for a longer period of time. don't run it too long. sounds like the ignition switch may possibly be failing. just a guess.

bliffle

RX,

Good suggestion. I was wondering about the ignition switch and wondering if I should hotwire it for a test. But I HATE to hotwire it! Maybe there are some other Ignition Switch phenomena, good or bad. But I'm getting desperate.

gsl-se addict

iTrader: (3)

If you weren't losing voltage, then I would say AFM. The fuel pump runs when cranking or when the AFM door is open. In this case (bad AFM switch), you would get fuel when cranking, it would start, and then die since the AFM door switch wouldn't keep the fuel pump relay energized.

Since you are losing voltage at the coils..there are two options that come to mind:
1. the main relay is bad
2. something is wrong with the ignition switch (which in turn energizes the main relay)
3. bad fusible link..the one marked 'computer' in the engine bay powers the coils and ECU

If the main relay cuts out, you will lose power to the injectors and the coils. This could be the ignition switch or the relay itself. The bad link will kill power to the coils and ECU. I don't really think it is the fusible link as it would probably work or not..not just work sometimes.

From the igntion switch, there is a BW (black w/ white stripe). This is active when key is turned to 'ON'. It powers the coils, charing system, and a bunch of other things. It looks as if it powers the power windows too, so maybe if you try the windows after it cuts out, that might tell you if the switch is bad. If the windows work, then the ignition switch should be okay.

Anyway..some ideas for you. Good luck.

Kent

RXnos1200

iTrader: (24)

^^^^^^ nice info.

bliffle

Hmmm. Well, I have to revise the symptoms: coil voltage is OK after engine quits. I just ran more tests with voltmeter.

After engine runs 10 secs and dies, it won't start immediately: gotta wait one minute for something to buildup. Maybe a capacitor someplace, like the ECU, so I bought a new ECU from one of the guys, it should be here in a couple days. In the meantime I'm gonna change the fuel filter and check the fuel pump.

The wiring diagram shows a 'condenser' , probably for relay arc suppression. I got blowups at Kinkos of the tiny wiring diagrams, which I'll study tonight.

bliffle

But it cuts out so quick it seems like it's gotta be electric. Maybe something in the FI system.

Rx-7Doctor

iTrader: (13)

Don't think you are going to find the ECU bad. You could do a pin test at the ECU to see if there is a problem with the rest of the system.

I'm with Kent on this. Sounds like either AFM or maybe main relay but most of the time with the main relay she won't start.

Why don't you try jumping the fuel pump circuit at the bypass located near the AFM and see if she will continue to run.

redfb

mine is doing the same thing let me know if you figure it out

bliffle

I'm starting to favor the AFM idea.

I'll try "jumping the fuel pump circuit at the bypass located near the AFM" when I figure out where the two contact points are physically located.

gsl-se addict

iTrader: (3)

There is a connector near the AFM with a rubber boot. Put a wire between the two terminals in that connector. That will bypass the AFM switch for the fuel pump and cause the fuel pump to run whenever the key is 'ON'. Just like the SAs and early FBs.

j9fd3s

iTrader: (3)

theres also a yellow 2 pic connector by the right strut tower, jump it and the fuel pump will run with the key.

bliffle

At least the ECU has test points and it may reflect the health of other parts.

If it's an AFM problem does one replace the whole AFM assembly?

bliffle

I'm not sure where to jump the connector. Is it someplace on these pix?