stroker393

90 V-6 with manual 4WD / was running fine but the next day engine will turn over but will not fire. I'm not the one to start throwing parts at anything and I'm out of ideas. I have spark at the plugs and fuel to the injector rail (top banjo bolt). I've ohmed the EFI main relay, circuit opening relay, start injector time switch, #1 injector and they check out. Plugs, cap, rotor and wires are new. When I turn the key from (off-ACC-on-start) it trys to fire for a split second but nothing. When I try to start again from (on-start) it doesn't try to fire so when I turn the key through its full range it trys to fire but when I quickly turn the key again without going all the way back to the off position it doesn't react the same. Could my problem be in the ignition switch? Everyone give any and all ideas; the help would be greatly appreciated and this is my first YOTA.

BMcEL

Try tapping the ignitor while you're cranking it over. Might want to check for codes too.

stroker393

I'll try the tap. Question on the igniter; is it in series with the coil or seperate and works for the injectors? I checked for codes first thing and it came up clean which sorta leads me to believe it is something simple that I'm over looking. keep'em coming guys. Thanks!

justin_4runner

if u are thinking its the ignition switch i would first check it and see if u get conuity threw it like it should if u really want u might be able to jump the switch to see if it changes anything,

stroker393

Seems like I'm backing up and making it worse. I now have no fire to the plugs so I replaced the coil and igniter, new EFI main relay and checked all fuses and F/link's again. It turns over fine but no spark at the plugs. I've got voltage at the coil and the igniter but nothing. It also does not show the CEL (red engine pic) in the dash when you turn the key on and even when I try to pull the codes nothing flashes. Is there something in this system that I'm overlooking?

rworegon

Did your timing belt go?

stroker393

I had spark last week but it wouldn't fire and now no spark. It doesn't feel like the belt went but I'll try anything now. To check if belt is spinning and OK; pull cap and see if rotor rotates - is that the quick way? What has me stumped is the spark then no spark. I installed the coil and igniter after I saw no spark on the original parts.

stroker393

Pulled the cap and the rotor rotates when you crank it so timing belt is intact. I did a complete timing job last year with belt, gears and idler. I'm trying to understand the wiring diagram in the chilton manual and if there is voltage going to the distributor from the plug/wiring. I have nothing with key off,on and start. The pickup coils/signal generator ohm out within specs and the cap, rotor and wires are new.

Kiroshu

Is there spark from the coil directly? If not then the area of trouble is in coil/ignitor circuit and or distibutor rpm pick-up.

stroker393

I'm trying to recall back last week when I had spark at the wires and then nothing. My son trying to help hooked up the big battery charger to it as the battery was getting drained from all the cranking and threw "200 amp quick start" to it one time. From that point on we had no spark. Could this have fried the ECU? No fuses blew, not even the fusible links but now the CEL is not even glowing on start up. Anyone have an opinion on that?

TNRabbit

Did you check the 80 amp fuse in the box on the passenger fender under the hood?

Team420

Tn is right on, check that 80 amp fuse... Also, spark/no spark... Try cleaning the grounds to the coil/igniter (where they bolt to the fender wall)

Kiroshu

Jumping Cars incorrectly can blow fuses to prevent circuit damage.

stroker393

That was my first thought after my son throwed the "200" to it. I've looked over the fuses and they all checked out except the 7.5 charge fuse in the box on the fender. It has nothing on either side when you pull the fuse out in all key positions and the fuse is not blown. Trying to understand this circuit "charge" in the manual and if the circuit doesn't even get hot until the circuit is needed for "charge". Not sure about that one. Checking the coil/igniter mount is something I can try and I guess now I'm past a quick fix as the mud slinger/deer hunter has been sitting for over a month. It was running great when I pulled into the driveway and shut it off. Minutes later came out to go again and it would not fire. It never gave any warning of problem creeping up on me. We did put a fuel pump on it after that thinking it was the issue - I never checked to see if I had fuel at the upper banjo fitting at the rail before we spent the time dropping the tank but fuel is pumping fine. Maybe somewhere there is a loose ground. The wiring diagram in the Haynes manual is a big help but are they complete or just a rough overview?
Thanks to everyone that as posted and keep them coming. I have learned that some problems are better figured out with more than one head dealing with auto issues.

stroker393

Well- I got back on the truck this past weekend as finding the time to work on it is tough. I checked it out to see if my problems were still the same and when I put in the key and turned it the check engine light glowed. Last week from earlier posts it would not come on. What made it cure itself with that issue? I checked spark to the plugs and I had spark now but still it would not fire up. I was able to pull codes now also. Counting the flashes gives me "24" and "31" which points to the AFM sensor/unit. Does anyone have any ideas/tests I can run on this part? Sorta baffled on how I can't get any codes to flash/no CEL/no spark and without touching anything I come back to truck a week later and it gives me codes/CEL glowing/have spark. Does that sound like a relay resetting itself with maybe temp change? Every problem has an explanation but this one is crazy.

Team420

Here ya go... hope it helps!

http://ncttora.com/fsm/1990-1995_4Rn...e/volumeai.pdf

rustyf99

iTrader: (1)

Right on! The VAFM will cause a no-start because the computer doesn't read that there is air moving into the intake manifold. That's where I would start, test that! I have a hunch you'll find a sticky spot where it's either not registering or a flat spot where it ohms the same over a wide range of opening.

ChefYota4x4

iTrader: (5)

Not sure if mentioned... But, seeing this is a MAF, not an AFM like I have, ....I would still assume it's similar in it's 'activation of the fuel pump'... Maybe it's intermittent or just plain dead on that portion? Can you bypass at the Diag. port for the FP and see?

Also see the 'ignitor' and 'igntion' stuff you brought up.... Good thing to verify, and there ARE tests in the FSM for the ignitor(just be careful! lol), as well as the IGN system. Switches can get wonky, but from what I remember, ...the ignitor usually just DIES, flat out. Heard SOME cases where it's acted up before completely failing... but more often than not, I believe they just die.

You said you checked a 'injector resistor'? (Not sure on a V6)... Just throwing stuff out there, as I CAN RELATE TO CHASING TAIL.... NO, not that kind, unfortunately... more of my own, like a confused dog! hahaha.

Best wishes, man!

stroker393

Ran the ohm tests on the MAF and one area was bad so I replaced with a good used MAF and now I have spark but still not firing the engine. It will turn over with no problems and try to fire but no crank. Checked to see if it had thrown a code and it did; "43" - Starter Signal / no STA signal to ECU until engine speed reaches 800 RPM with vehicle not moving. The trouble area would be IG switch circuit, IG switch or ECU. I tryed B+ to Fp and no change. I have pulled the key cylinder and ignition switch out and did see that there were some sloppy areas in the cylinder and the switch. Does anyone know what they mean when they list the ignition switch as USA or Japan built? I see no markings on my OEM one.

Hadmatt54

Is your charge warning light lighting up when you turn on the key? It is fed from the 7.5 amp ignition fuse, then to the alternator, but the 7.5 amp ignition fuse also feeds the coil side of the EFI main relay. I know you said you checked all of the fuses, but I have seen fuses that the element looked perfect, but they had opened under the plastic. I do a continuity on all of my fuses after finding that one, you might want to do that on the 7.5 ign fuse....because if it's gone your coil in the EFI won't get energized and the contact in the relay won't close and you'll never get your truck started.