1997 FZJ80 stalling/stumbling at random

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OK so this is more of a sanity check than a specific question.

Here's the background: I bought a 1997 80 series this past May and have been enjoying it ever since. A few days after our last camping trip I was driving around town and all of a sudden I lost power, the engine began to miss, and I was forced to coast into a gas station. I knew I had less than a quarter tank of gas so my first thought was that I had run it out of gas (even though the low fuel light never illuminated). I figured the low fuel light had gone out so I put several gallons of gas in the tank and tried to drive home. She fired up and acted fine for a second but then began to miss again. I was able to limp home and for a while the truck acted fine. After thinking about our trip I realized we had driven through some reasonably deep water and it occurred to me that I may have a moisture issue. The truck was driving fine, I thought the stalling was weird but it seemed to have gone away so I chalked it up to some wires getting wet and figured they had dried out. Then, a couple weeks later, my wife was driving the cruiser and had the same weird behavior. There was more than enough gas in the tank at the time so that rules out simply "running it dry".

My current thought process:

Obviously I want to take care of this problem and have the truck back to normal. I have been reading and searching on this forum and finding a lot of good information. I have had a P0401 code (insufficient exhaust flow) for a while and I think some of the vacuum lines are old/dry rotted so I know I need to take a look at the EGR system. The following are things that I intend to check/work on as soon as I can (probably sometime next week):

1.) fuel filter - possibly clogged/starving engine?
2.) fuel pump - check resistance as per FSM, maybe it's starting to bite the dust
3.) EGR modulator - check filter/clean
4.) vacuum lines - replace as needed
5.) throttle body - remove/clean
6.) plenum - remove top half, clean, remove carbon from small vacuum port (the little one that goes straight through and gets clogged with carbon)

This is where the sanity check comes in - am I missing something obvious that could be causing this stalling/lack of power? The items above are what I was able to reason out on my own or find from reading on Mud. Any suggestions would be welcome. I don't have the money to start throwing parts at this vehicle but I want to fix whatever is actually wrong and I want to do it right.
 
Had the same symptoms on my 94. Limped it home. Checked the vacuum lines, nothing. Started and ran fine for a week, then same symptoms. Replaced the throttle position sensor (OEM), it had an aftermarket one. No issues since. I don't like throwing parts at it either, but the TPS is deff a sensor that will go over time. Found one on Ebay for $90.
 
I had similar symptoms six months after buying mine. Turned out to be the fuel pump relay. It is about US$65. (Note: IIRC this problem manifests itself when the engine is hot. And it gradually worsens over time. ie, it will cut out more and more frequently)

A year after that, I had similar symptoms again. Turned out to be the fuel pump gradually failing. This is US$100-150.
 
Thanks for the info. I had a hunch it was something in the fuel system. I guess I'll find out when I start taking things apart and testing them.
 
Had the same symptoms on my 94. Limped it home. Checked the vacuum lines, nothing. Started and ran fine for a week, then same symptoms. Replaced the throttle position sensor (OEM), it had an aftermarket one. No issues since. I don't like throwing parts at it either, but the TPS is deff a sensor that will go over time. Found one on Ebay for $90.

Thanks for the tip. I will keep this in mind if the other repairs don't take care of the issue.
 
This is my first cruiser so I'm learning as I go and suggestions from people who have worked on these things before are invaluable.
 
You can change the fuel pump relay in five minutes.

You can change the fuel pump in an hour or so. The time consuming part is moving out all the rear seats.

Make sure you change the in - tank fuel filter while you are in there. Denso sells a kit with both pump and filter. Get that one.
 
The very first and simplest thing to do is replace the fusible links coming off the positive terminal of the battery. Cost about $15 from your local Toyota dealer or vendors on this forum.

First thing to check when you have a failure is that the check engine light is lite when you turn the ignition to ON before starting. If it does not illuminate the ECM is not getting power and the engine will not start.
 
The very first and simplest thing to do is replace the fusible links coming off the positive terminal of the battery. Cost about $15 from your local Toyota dealer or vendors on this forum.

First thing to check when you have a failure is that the check engine light is lite when you turn the ignition to ON before starting. If it does not illuminate the ECM is not getting power and the engine will not start.

I appreciate the suggestion and I will keep it in mind. For now it cranks fine - just doesn't stay that way. And, it has been sporadic which makes diagnosing the problem a bit difficult.
 
With a fusible link failure the engine will crank normally it just won't start or it could shutdown as you have experienced intermittently.
 
So the fusible link fails causing intermittent current to the spark wires which leads to a misfire? And if that is the case, why would it idle/limp home but have issues accelerating? I'm not saying you're wrong, just trying to understand.
 
You can replace a bunch of random parts and hope, or do some diagnoses and find the root problem. The first observation is; when it dies, before touching the key, is the CEL on? If not, it most likely has a power loss to the ECU, not going to run. The fuel pump relay, remove it and jumper term #5 to #3, this makes the pump run full speed. If it doesn't have the issue in this mode, the relay is likely bad.
 
You can replace a bunch of random parts and hope, or do some diagnoses and find the root problem. The first observation is; when it dies, before touching the key, is the CEL on? If not, it most likely has a power loss to the ECU, not going to run. The fuel pump relay, remove it and jumper term #5 to #3, this makes the pump run full speed. If it doesn't have the issue in this mode, the relay is likely bad.

That's a fair point, which is exactly why I just purchased a multimeter to help me rule out electrical components using the specs in the FSM.
 
When my fuel pump relay malfunctioned, it do so sporadically. And seemed to fail only when the engine was hot.

So you have to do the test when the car cuts off.

When you jumper the fuel pump relay, make sure you get a good connection. I got a false negative the first time because I only used raw wire

Google "Emergency Troubleshooting Procedure FZJ80 PDF".

Print and put it in your glovebox
 
96/97 harness runs across a bracket at the ECU.....very common spot where rubbing eventually hits a cyl misfire.

Pull glovebox and inspect harness at the bend/kink wiring before the ecu. Easy one to rule out.

Then check egr pipe/ harness point for crunchy harness.....peel open if it is.....and inspect. Another easy one that should be inspected and ruled out anyway. And if pipe is contacting harness.....ziptie it away fom pipe.

Are you getting any codes?
 
I recently tested and then removed the No 1 O2 sensor and the truck ran just fine. Pretty sure I have a clogged cat.
 
i know this is an old thread but did the original poster solve their issue? i'm having the exact same symptoms on my 1993 fzj80, sporadic shutdowns after about 45mins of driving, starts right back up immediately...drives great outside of this issue, just starting testing procedures. Just curious if you got yours solved...thanks!
 
i know this is an old thread but did the original poster solve their issue? i'm having the exact same symptoms on my 1993 fzj80, sporadic shutdowns after about 45mins of driving, starts right back up immediately...drives great outside of this issue, just starting testing procedures. Just curious if you got yours solved...thanks!
What codes are you getting back? There’s an ODB2 on all the FZ engines correct? Or have you checked O2 sensors and or Cat status? Is it the stock exhaust that’s been there forever?
 
What codes are you getting back? There’s an ODB2 on all the FZ engines correct? Or have you checked O2 sensors and or Cat status? Is it the stock exhaust that’s been there forever?
mine's a '93 so i have OB1...no CEL, which is good i guess...i've recently replaced both cats and 02 sensors with NTKs. Rig runs great outside of a random shut down after 40ish minutes then fires back up
 

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