No check engine light (1 Viewer)

[slimdusty]

Couple of thoughts.
If the ECU is not getting power, there will be no codes to read.
The fuel pump only runs when cranking the starter, not just with the key in the ON position.
The 3FE doesn't have a "fuel pump relay". It's called a circuit opening relay and it is fired from the starter circuit.
Without the CEL on, you have a 6000 pound paperweight. Have a look at the resources section and download the 3FE EFI troubleshooting flowchart.

General Tech - 3FE EFI Diagnostics

3FE EFI Diagnostics updated for 2020

forum.ih8mud.com

jon im so sorry im new to the forum and to this truck im just now seeing everyones replies now. The truck is towed back to the shop. thank you so much for your input. I tried to open the pdf everyone says to open that you wrote but it will not open no matter how many times i click it or where i click it from. I dont understand why i cant open that flow chart. Im not a mechanic or a computer wizz but im pretty good at getting things done on both my computer and my trucks lol. Sorry i also wrote to you on another thread not realizing you replied. The guy that owns the shop is chasing no spark now. He found proper voltage to the fusable links although i have to say they are corroded badly, he also found power to the circuit open relay, efi relay and he tested a bunch of stuff. He eliminated some wiring where there was an aftermarket car alarm that was a bit of a rats nest. He seems like an amazing mechanic that is very knowledgeable and helpful. He is thinking now that it is the distributor and he ordered one to install tomorrow. I however can not get it out of my head that the CEL stopped working at some point during all of this. What could i have done to cause that? All i did while waiting on a tow was, replace efi relay and the battery. One other thing i did was removed the MAF to clean it but I actually pulled the 2 screws first instead of unclipping it. Could I have done something to stop the CEL during that time? Did the ECU conveniently die at this exact moment? god this thing is driving me insane. Sorry for the ramble as stated im new to navigating a forum and to this truck. thanks again

 

[BILT4ME]

jon im so sorry im new to the forum and to this truck im just now seeing everyones replies now. The truck is towed back to the shop. thank you so much for your input. I tried to open the pdf everyone says to open that you wrote but it will not open no matter how many times i click it or where i click it from. I dont understand why i cant open that flow chart. Im not a mechanic or a computer wizz but im pretty good at getting things done on both my computer and my trucks lol. Sorry i also wrote to you on another thread not realizing you replied. The guy that owns the shop is chasing no spark now. He found proper voltage to the fusable links although i have to say they are corroded badly, he also found power to the circuit open relay, efi relay and he tested a bunch of stuff. He eliminated some wiring where there was an aftermarket car alarm that was a bit of a rats nest. He seems like an amazing mechanic that is very knowledgeable and helpful. He is thinking now that it is the distributor and he ordered one to install tomorrow. I however can not get it out of my head that the CEL stopped working at some point during all of this. What could i have done to cause that? All i did while waiting on a tow was, replace efi relay and the battery. One other thing i did was removed the MAF to clean it but I actually pulled the 2 screws first instead of unclipping it. Could I have done something to stop the CEL during that time? Did the ECU conveniently die at this exact moment? god this thing is driving me insane. Sorry for the ramble as stated im new to navigating a forum and to this truck. thanks again

If it fired with ether then it has spark and it is NOT the distributor. Period.

 

[slimdusty]

If it fired with ether then it has spark and it is NOT the distributor. Period.

I sprayed some ether in there and it stumbled and seemed like it was trying to start. He hooked up some thing to the wires and distributer to check for spark when i had it towed back. He had me turn the key and didn't get any spark he said. Its driving me insane that the CEL light worked and then stopped working that is one thing that makes no sense to me. Then again none of this makes sense. The reason I always buy toyotas is they are usually reliable LOL. thanks for your help man this is really frustrating

 

[slimdusty]

jon im so sorry im new to the forum and to this truck im just now seeing everyones replies now. The truck is towed back to the shop. thank you so much for your input. I tried to open the pdf everyone says to open that you wrote but it will not open no matter how many times i click it or where i click it from. I dont understand why i cant open that flow chart. Im not a mechanic or a computer wizz but im pretty good at getting things done on both my computer and my trucks lol. Sorry i also wrote to you on another thread not realizing you replied. The guy that owns the shop is chasing no spark now. He found proper voltage to the fusable links although i have to say they are corroded badly, he also found power to the circuit open relay, efi relay and he tested a bunch of stuff. He eliminated some wiring where there was an aftermarket car alarm that was a bit of a rats nest. He seems like an amazing mechanic that is very knowledgeable and helpful. He is thinking now that it is the distributor and he ordered one to install tomorrow. I however can not get it out of my head that the CEL stopped working at some point during all of this. What could i have done to cause that? All i did while waiting on a tow was, replace efi relay and the battery. One other thing i did was removed the MAF to clean it but I actually pulled the 2 screws first instead of unclipping it. Could I have done something to stop the CEL during that time? Did the ECU conveniently die at this exact moment? god this thing is driving me insane. Sorry for the ramble as stated im new to navigating a forum and to this truck. thanks again

Couple of thoughts.
If the ECU is not getting power, there will be no codes to read.
The fuel pump only runs when cranking the starter, not just with the key in the ON position.
The 3FE doesn't have a "fuel pump relay". It's called a circuit opening relay and it is fired from the starter circuit.
Without the CEL on, you have a 6000 pound paperweight. Have a look at the resources section and download the 3FE EFI troubleshooting flowchart.

General Tech - 3FE EFI Diagnostics

3FE EFI Diagnostics updated for 2020

forum.ih8mud.com

I went to the resources tab and went to fj80 section and scrolled them all none of which were labeled 3fe troubleshooting flowchart. I also searched for those keywords and got nothing. I have always been terrible at navigating forums. I feel like it can't be as hard as I make it.

 

[BILT4ME]

I went to the resources tab and went to fj80 section and scrolled them all none of which were labeled 3fe troubleshooting flowchart. I also searched for those keywords and got nothing. I have always been terrible at navigating forums. I feel like it can't be as hard as I make it.

Select the link and download the document to your phone or computer. If it asks you what program to read it with, use Word if you can.

If that doesn't work, then I'll post screenshots of it.

 

[BILT4ME]

Select the link and download the document to your phone or computer. If it asks you what program to read it with, use Word if you can.

If that doesn't work, then I'll post screenshots of it.

 

[slimdusty]

Select the link and download the document to your phone or computer. If it asks you what program to read it with, use Word if you can.

If that doesn't work, then I'll post screenshots of it.

Thanks man. My guy said he pulled the distributor before he closed and it was full of rust/ corrosion.

I think I found the link everyone is talking about does it read this at the top:

“Diagnostic Procedure for 1991/1992 3F-E EFI Related Issues Motor not running; key in ON position; CEL, A/T, CHARGE lamps should be on.
No CEL=No Start”???

I also have just discovered Jon’s tune up guide and for people to stop complaining about no power and reliability on a 30 year old car that no maintenance has been done on . Looks like I have a long road ahead of me and need to start ordering parts lol

 

[BILT4ME]

Thanks man. My guy said he pulled the distributor before he closed and it was full of rust/ corrosion.

I think I found the link everyone is talking about does it read this at the top:

“Diagnostic Procedure for 1991/1992 3F-E EFI Related Issues Motor not running; key in ON position; CEL, A/T, CHARGE lamps should be on.
No CEL=No Start”???

I also have just discovered Jon’s tune up guide and for people to stop complaining about no power and reliability on a 30 year old car that no maintenance has been done on . Looks like I have a long road ahead of me and need to start ordering parts lol

Jon is the go-to guy on these early trucks. He knows his stuff.

 

[ppc]

One other thing i did was removed the MAF to clean it but I actually pulled the 2 screws first instead of unclipping it. Could I have done something to stop the CEL during that time? Did the ECU conveniently die at this exact moment? god this thing is driving me insane. Sorry for the ramble as stated im new to navigating a forum and to this truck. thanks again

What you are referring to as the MAF is called the AFM or VAF on the 3FE motor. By trying to open it via the two screws was a very big mistake and most likely have damaged it. Within that device there is a set of contacts that shuts down the fuel pump when the vane does not open to lack of air flow. A safety feature to prevent gasoline from starting a fire. There are a few threads describing attempted repairs as it is a discontinued part and very difficult to source on the used market. There are a couple of company that do rebuilds that you can find by searching the forum.

At what point did you make this error, before the disappearing CEL or after?

 

[BILT4ME]

What you are referring to as the MAF is called the AFM or VAF on the 3FE motor. By trying to open it via the two screws was a very big mistake and most likely have damaged it. Within that device there is a set of contacts that shuts down the fuel pump when the vane does not open to lack of air flow. A safety feature to prevent gasoline from starting a fire. There are a few threads describing attempted repairs as it is a discontinued part and very difficult to source on the used market. There are a couple of company that do rebuilds that you can find by searching the forum.

At what point did you make this error, before the disappearing CEL or after?

I totally blew past this part of his paragraph.

Yup, most likely the culprit.

 

[slimdusty]

What you are referring to as the MAF is called the AFM or VAF on the 3FE motor. By trying to open it via the two screws was a very big mistake and most likely have damaged it. Within that device there is a set of contacts that shuts down the fuel pump when the vane does not open to lack of air flow. A safety feature to prevent gasoline from starting a fire. There are a few threads describing attempted repairs as it is a discontinued part and very difficult to source on the used market. There are a couple of company that do rebuilds that you can find by searching the forum.

At what point did you make this error, before the disappearing CEL or after?

Hey man thank you for the help and input. I am kicking myself over opening that up and i also was up half the night thinking about this damn thing. Its funny though you mention it because the more i think about it the more i think the CEL light actually went out before I messed with the AFM. The only thing i had done at that point was swap the ICU relay and wiggle it and the old one. The toyota tech also beat on the gas tank with a rubber mallet as he suspected fuel pump. Man i cant say for sure but i am about 95% the CEL went out before taking those screws out. I got so frustrated and impatient I started doing anything I thought could help and walked to autozone for new battery and maf cleaner. Soon as I opened it and saw the electrical components I put it back because i knew i had made a mistake. Im hoping i didnt damage it but I guess i probably did. CEL being out it so freaking weird! I sent some of the info from this forum to the guy with the truck last night. In particular the fusable link info. He said the inside of the distributer was corroded badly like it had seen water so im hopeful for that, but still concerned its not going to help without the CEL per your guys input. UGHHHH I also didnt realize parts were so scarce for these. Usually you can get a afm replacement just about anywhere. I have an 88 pickup and a 90 4runner that i thinker with and never had any trouble finding parts. thanks again for your help, hopefully today we figure soomething out. Im suppose to be driving this truck back to the beach tomorrow but my hopes for that are dwindling.

 

[jonheld]

A bad/faulty distributor will not prevent the CEL from illuminating.
The lack of the CEL indicates that the ecu is not in a "ready" state and this engine will not run.
If you suspect the AFM, then disconnect the connector by lifting the thin spring clip on the connector housing to separate. If the CEL returns, then you have your issue.
As stated previously, the AFM runs the fuel pump after the engine catches.
Again, no CEL=no start.
Follow the flowchart.

 

[slimdusty]

A bad/faulty distributor will not prevent the CEL from illuminating.
The lack of the CEL indicates that the ecu is not in a "ready" state and this engine will not run.

I understand that now and have forwarded that to the tech. I'm just wondered if the distributer was the original reason it would not start before the CEL stopped illuminating.

 

[jonheld]

I understand that now and have forwarded that to the tech. I'm just wondered if the distributer was the original reason it would not start before the CEL stopped illuminating.

Impossible to say. Right now your only focus should be the CEL. ECU failures are extremely rare on the 3FE. Not impossible, but not likely. Fusible links, connector EB1 (just north of the fender mounted relay box) is where I'd be looking, but verify the AFM first.

 

[slimdusty]

Impossible to say. Right now your only focus should be the CEL. ECU failures are extremely rare on the 3FE. Not impossible, but not likely. Fusible links, connector EB1 (just north of the fender mounted relay box) is where I'd be looking, but verify the AFM first.

Thank you Jon I have forward that to him as well. Hopefully he appreciates and is not offended by my “side advice” from you guys. If I was working on it I would appreciate any help I could get. I know he wants it out of his parking lot so that helps lol.

 

[jonheld]

Thank you Jon I have forward that to him as well. Hopefully he appreciates and is not offended by my “side advice” from you guys. If I was working on it I would appreciate any help I could get. I know he wants it out of his parking lot so that helps lol.

Below is a full schematic of the 3FE ECU and related components. Wire colors are accurate.

Connector EB1 in the engine bay. All ECU +12 runs through this connector.

Location of EB1

 

[slimdusty]

Below is a full schematic of the 3FE ECU and related components. Wire colors are accurate.

Connector EB1 in the engine bay. All ECU +12 runs through this connector.
View attachment 3391703

Location of EB1

View attachment 3391704

Below is a full schematic of the 3FE ECU and related components. Wire colors are accurate.

Connector EB1 in the engine bay. All ECU +12 runs through this connector.
View attachment 3391703

Location of EB1

View attachment 3391704

Wow thank you jon. Im curious what am i looking for in the EB1 connector? Sounds like that is a very important spot. Unfortunately I did not hear from the shop at all today I'm hoping its because the truck is outside and it rained all day and not because he is sick of this stupid toyota in his lot. At this point i wish i had it at home to troubleshoot it myself. I feel like i have learned enough from you guys to possibly tackle the job. I am DYING to pull the AFM and see if check engine light returns. If i had a spare key I would do it now. I am also DYING to replace the corroded fusable links to see if that does it. Toyota said they could have them next day but I am trying to not be a know it all and let this mechanic do his thing. Trying not to step on toes so to speak. He did tow it for me for free and agreed to help me fix it. Im worried at the same time he views it as a nightmare and it will fall on the backburner. Im suppose to leave town tomorrow and still not sure what I am going to do. This sucks I just want my new truck back.

 

[slimdusty]

Below is a full schematic of the 3FE ECU and related components. Wire colors are accurate.

Connector EB1 in the engine bay. All ECU +12 runs through this connector.
View attachment 3391703

Location of EB1

View attachment 3391704

One other think I woke up thinking about in the middle of the night was when I was first checking my truck over I noticed the overhead dome lights didn’t work. I don’t know if that is the bulbs or not but I see it is one of the checks for fusible link. Do you happen to know if that is the link that will also kill the CEL? I ordered the link it will be here tomorrow am. I am also going to go unplug the AFM this morning. Jon am I correct in understanding that if I unplug AFM CEL should come back if the AFM is the issue? Thanks and happy Friday

 

[jonheld]

Below is a block diagram of the electrical system. There is a 10 amp fuse for the dome lights, which are off of FL AM1. If that FL was open, the starter would not crank and the CEL would not illuminate. FL MAIN provides power to the ECU and EFI control system.
Yes, you are correct. If the internals of the AFM have been damaged, it can prevent the CEL from illuminating. If you disconnect the AFM and the CEL comes back, then the AFM is the culprit.

 

[jonheld]

Im curious what am i looking for in the EB1 connector?

Corrosion, poor connectivity, burn marks, anything that does not look healthy. If you have the ability to use a multimeter, it can be your best friend.
This is first generation EFI, designed in 1986. There's very little magic going on here, and almost everything can be tested/verified with a multimeter and schematic.