92 FJ starts, then dies.... (1 Viewer)

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Jul 6, 2007
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Ogden, Utah
My 92 the other day, started, but then died after about 5 sec....WTF. I went through all the wiring, vacum hoses, and even checked codes, but no codes. I checked to see if the fuel pump was gone, I did have power to it. Then I pulled the fuel line of the pump and did have fuel pumping. I had the girl towed to my mech. That was sad to see her on top a flat bed.

I just read a thread, that was posted and you guys talked about the EFI relay. Could this be a possible problem? My mech has had it for a day and half now with now calls. Maybe I will call and let him now about the relay. Any other possible ideas on what is going on? More about what had happen, The day before when pulling up to the light, it stubbled then died, she started right back up. I got to work, she sat for 24 hrs, got off shift, went to start, she started for about 5 secs, then died, tried again same but shorter time. Hope this helps for you tech heads, give any input,PLEASE.:cheers: WoodyFJ
 
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it could be but that seems to usually be an issue with heat, and im assuming its not real hot in Utah right now
 
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Update

Just spoke to my mech. and said there was a problem with the relay, but there was a problem with my MAF sensor. If he unplugs the sensor it starts and runs. Now, the MAF is a rebuilt for the old one had some wiring problems inside(connections came unsoldered). I do have a K & N filter and we are thinking that is a problem for the sensor, so I will be ordering a new OEM washable filter from CDan ASAP.
My mech. is going to try to clean the sensor. I hope this is the problem and just a new filter will fix it. A new sensor is $$$$$.
All though he did find a new for $240, but it is a few days out.

Please any thoughts that I may pas along to my mech. would be very helpful. Thanks WoodFJ80
 
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Just spoke to my mech. and said there was a problem with the relay, but there was a problem with my MAF sensor. If he unplugs the sensor it starts and runs.

First of all you have an AFM not an MAF. Second. if he unplugged the AFM connector, the truck would die as the fuel pump would be cut off.

Something is rotten in Denmark.
 
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Ogden, Utah
It was the AFM(thanks Jon for the correction), I went to the mech and watched him unplug it and it did idle(run), ordered a new one from CDan, jsut waiting on it, hope this is the problem.
Any other ideas would be great.:cheers:WoodyFJ80
 
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Hense my "something is rotten" remark. The switch in the AFM is the ground path for the circuit opening relay (fuel pump relay). Once that connector is removed, the coil is no longer energized and the fuel pump should cut off.

The fact that it works with the AFM unplugged tells me that something has been molested somewhere in your truck or there is a possible short somewhere.
 
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Hense my "something is rotten" remark. The switch in the AFM is the ground path for the circuit opening relay (fuel pump relay). Once that connector is removed, the coil is no longer energized and the fuel pump should cut off.

The fact that it works with the AFM unplugged tells me that something has been molested somewhere in your truck or there is a possible short somewhere.


Jon,

I just when outside and tried this out of plain old curiosity. Also, there's pretty much zero chance my rig's electronics have been messed with.

Started the rig (engine cold if that matters), popped the hood, unplugged the AFM: The motor immediately stumbled (as I was thinking, "I'll be darned, ol' Jon's right again." :D ;)), BUT, it did NOT stall; rather, within just a second or two it started running "normally" again. (I didn't attempt to drive it though.)

I'm thinking the ECU noticed the problem and quickly went into "open loop"/safe mode operation, no?

Whaddaya think?

Curtis
 
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Mine did the same thing that Curtis described. I am the second owner on mine, and I know that the electronics have not been messed with. I am not doubting Jon at all his knowledge is great. Just alittle FYI: My AFM is a rebuilt, I did notice that the cover for the adjusting screw for the rich/lean is off, I did a few days before all this started rinsed off the grime in the engine compartment before doing my idler pulley bearing. I noticed some water in that tube for the screw. So, I am thinking that water seeped into the AFM through and shorted the AFM. I am thankful for MUD and keeping me to purchase nothing but OEM PARTS! A word for the wise:Don't cheap out on parts buy OEM! CDan is great for that! I will post when the part comes in this week and I get it replaced. Thanks for the inputs Jon and others!
 
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Jon,

I just when outside and tried this out of plain old curiosity. Also, there's pretty much zero chance my rig's electronics have been messed with.

Started the rig (engine cold if that matters), popped the hood, unplugged the AFM: The motor immediately stumbled (as I was thinking, "I'll be darned, ol' Jon's right again." :D ;)), BUT, it did NOT stall; rather, within just a second or two it started running "normally" again. (I didn't attempt to drive it though.)

I'm thinking the ECU noticed the problem and quickly went into "open loop"/safe mode operation, no?

Whaddaya think?

Curtis

I think I'm wrong? I dunno.

I remember pulling the connector off the AFM and the motor stalling, but that was a long time ago and I am old and crusty. I will have to re-check that, but I'm 99.999% sure I am reading the schematic correctly. The Fuel pump relay (COR) has 2 coils. One for "startup" fired by the starter cranking circuit through the neutral start switch, and one for "run" fired by the EFI relay and air flow switch in the AFM. Once the ignition switch is in the ON position, current flows from the EFI relay through the coil AND contactor side of the COR. The contactor side finds ground through the fuel pump motor and the logic side goes to ground through the switch in the AFM. I believe this is a safety feature. If the motor is not running (AFM switch open) the fuel pump is off. This can be verified by monitoring the voltage on pin 1 on the check connector (FP) to ground.

If the motor is running and the AFM is disconnected, the coils in the COR cannot be energized because there is no longer a ground path and the fuel pump will shut off.

It is entirely possible that the schematic is wrong and the only way to test that is to ohm it out.
 
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Maybe I wasn't patient enough, and it would have eventually died from a lack of fuel?

:meh:
 
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Rhode Island
I just went out and tried this. The truck has been running for about 10 minutes with the AFM unplugged with only the silly CEL on to bother me.
 
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Sorry, My wife just left with the 80. I will get the code and post up when she gets back from work. It may be tomorrow before I get it. Da!% overnight emergency shifts at the animal hospital.
 
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OK guys. I couldn't stand it any longer. Started up the truck just now after sitting all day. Popped the hood and pulled off the AFM connector. She stumbled and died. On a re-start she would fire and die. IOW it is acting EXACTLY as shown in the EWD. When running the fuel pump switch is the AFM. When cranking to start the fuel pump is powered from the start circuit.

That leaves 2 possibilities running around my brain. It is possible that Toyota made 2 different COR for these trucks. I will contact John Hocker and find out the skinny on that. The other possibility is that the capacitor in the COR (to prevent relay bounce) has shorted. If that happened then the run coil would be energized as soon as the EFI relay closed.

For those that say that the truck will run without the AFM connected, please monitor the voltage on the FP terminal on the check connector by the firewall. On yours it sounds like it would read +12 with the ignition switch in the ON position with the motor not running. If you have a spare COR swap it in and see what happens. If not, I might have one laying around that I could send out.
 
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I've been trying this throughout the day. If my truck is warm, it tends to keep running but when it's cold it will start and die. I'll bet the relay is sticking when it's hot. I'll get a new one and report back. In the meantime I'll see if I have 12v+ at the FP terminal when it runs with the AFM disconnected. Right now I do not have 12v at the terminal and it will not run with the AFM disconnected.
 
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I've been trying this throughout the day. If my truck is warm, it tends to keep running but when it's cold it will start and die. I'll bet the relay is sticking when it's hot. I'll get a new one and report back. In the meantime I'll see if I have 12v+ at the FP terminal when it runs with the AFM disconnected. Right now I do not have 12v at the terminal and it will not run with the AFM disconnected.

LOL. If the motor is running then you're gonna have +12 at the FP terminal. FWIW, I replaced my COR about 2 years ago. Tried to call JH, but the new phone system spanked me, so no answer. According to the EPC I have, there was 1 part number for the COR from 1/90-1/95. Part number 85910-30050. IIRC this was not a cheap relay. I want to believe I still have my original one somewhere in a box. I'll poke around a bit this weekend.

This is good stuff BTW. Like a treasure hunt.
 

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