1994 KZJ78W Loss of Power and Misfire

[TAMF67]

Hi All!

I am the proud owner of a 1994 KZJ78W Land Cruiser Prado that I imported from Japan. Overall I love the truck but unfortunately we have been running into issues with a loss of power, and misfiring while in idle. The last time this happened the Toyota Dealership near me adjusted the fuel injection rate to where it was idling 800-900RPM and that seemed to fix the issue for like six months. However, recently the issue came back right after I got a new tank of diesel. My wife was driving and the truck was barely able to remain running while idling. So we had it towed to the dealership again and they adjusted the rate again which helps keep it running in idle but roughly and at 1000 RPM now. They are recommending replacing the fuel pump (item number 22100-67070). I ordered the fuel pump, yet despite it having the same part number shown on the schematics, and that on the pump installed it does not match the configuration. At this time I cannot find one that matches the one installed in my truck. I think the issue is that mine is Japanese model and all the parts on eBay are hilly models. Is there a way to rebuild the fuel pumps or are we chasing a rabbit down a hole here?

 

[Jonesey]

Is this your pump? Same part number noted. This shop is in Oregon and they do a lot of work on the import diesels. Give them a call, ask them condition of the pump. I recommend getting a genuine pump.

1KZ-TE Fuel Injection Pump — Fit Garage

Genuine OEM Toyota 1KZ-TE Fuel Injection Pump 22100-67070

www.thefitgarage.com

 

[Bad Mojo]

What is the difference between what is on your engine currently and the on ordered? Do you have any pictures? For our 1995 KZJ78 22100-67070 is the correct injection pump number.

The other thing I would look at is the ECU. They are reaching the age they start to fail and cause various types of gremlins that have people chasing all over the truck to only find the ECU needs new capacitors put into it. I need to check, but I wonder if the ECU controls some of the idle on that truck.

 

[Rigster]

Not to speak ill of the dealership and their ability to troubleshoot the issues you are seeing, but this problem you are speaking of may be as simple as a small pinhole or some old fuel lines hardening up and no longer sealing at the clamps, or both. Air creeps into the system and can cause this. Does it take longer to start when it has been shut off for a while? Another telltale sign. I would just hate to see you put an expensive part like a fuel pump in there and have it still doing the exact same thing. Easiest way to tell if there is air getting into the system is to temporarily install a clear hose from the filter to the pump and watch for bubbles while it is idling. There are a few threads on mud that go into great detail chasing down these leaks. Best of luck getting this one squared away....

 

[JuanJ]

Not to speak ill of the dealership and their ability to troubleshoot the issues you are seeing, but this problem you are speaking of may be as simple as a small pinhole or some old fuel lines hardening up and no longer sealing at the clamps, or both. Air creeps into the system and can cause this. Does it take longer to start when it has been shut off for a while? Another telltale sign. I would just hate to see you put an expensive part like a fuel pump in there and have it still doing the exact same thing. Easiest way to tell if there is air getting into the system is to temporarily install a clear hose from the filter to the pump and watch for bubbles while it is idling. There are a few threads on mud that go into great detail chasing down these leaks. Best of luck getting this one squared away....

Hello,

x2.

It is wise to drop in an additional fuel filter.





Juan

 

[TAMF67]

Is this your pump? Same part number noted. This shop is in Oregon and they do a lot of work on the import diesels. Give them a call, ask them condition of the pump. I recommend getting a genuine pump.

1KZ-TE Fuel Injection Pump — Fit Garage

Genuine OEM Toyota 1KZ-TE Fuel Injection Pump 22100-67070

www.thefitgarage.com

Thanks for the reply. This is the pump that I ordered that did not match, (Diesel Fuel Injection Pump For Toyota 3.0L 1KZ-TE Prado Hilux HiAce 22100-67070 | eBay - https://www.ebay.com/itm/145354164161) which makes me think that it might not be a throttle actuated pump? This is the pump I am looking at trying next (Toyota Land Cruiser Prado Colorado Hilux 1KZ-TE Fuel Injection Pump 22100-67070 | eBay - https://www.ebay.com/itm/395442102147). It looks similar but I have not actually pulled the pump yet.

Thanks for the recommendation for the pump. I called them and once I can verify if it at least looks similar I will probably go with them.

 

[TAMF67]

Not to speak ill of the dealership and their ability to troubleshoot the issues you are seeing, but this problem you are speaking of may be as simple as a small pinhole or some old fuel lines hardening up and no longer sealing at the clamps, or both. Air creeps into the system and can cause this. Does it take longer to start when it has been shut off for a while? Another telltale sign. I would just hate to see you put an expensive part like a fuel pump in there and have it still doing the exact same thing. Easiest way to tell if there is air getting into the system is to temporarily install a clear hose from the filter to the pump and watch for bubbles while it is idling. There are a few threads on mud that go into great detail chasing down these leaks. Best of luck getting this one squared away....

Thanks for the reply! I am starting to second guess my choice. They have a history of working with American made Land Cruisers but I think their knowledge on diesels is not the best. Im thinking of taking it out of the dealership and working on it myself. It is exceedingly difficult to work with them because it becomes a game of telephone. I'll have to walk the entire wire harness. I wish there was somewhere near here in Boston that had experience with Japanese made KZJ78s.

 

[TAMF67]

What is the difference between what is on your engine currently and the on ordered? Do you have any pictures? For our 1995 KZJ78 22100-67070 is the correct injection pump number.

The other thing I would look at is the ECU. They are reaching the age they start to fail and cause various types of gremlins that have people chasing all over the truck to only find the ECU needs new capacitors put into it. I need to check, but I wonder if the ECU controls some of the idle on that truck.

Thanks for the reply. I posted above what the pump I ordered looked like. I am going to try to pull the fuel pump and get a photo of it. I was able to finally get the dealership to remove the ECU while I was there. It looks absolutely brand new so that is a bonus.

 

[Rigster]

Thanks for the reply! I am starting to second guess my choice. They have a history of working with American made Land Cruisers but I think their knowledge on diesels is not the best. Im thinking of taking it out of the dealership and working on it myself. It is exceedingly difficult to work with them because it becomes a game of telephone. I'll have to walk the entire wire harness. I wish there was somewhere near here in Boston that had experience with Japanese made KZJ78s.

I do not let anyone work on my Land Cruiser but me. There is one old school shop in town I will get to do things like a wheel alignment or AC charging as I do not have that equipment, otherwise I just do everything. It makes owning a Land Cruiser reasonable.

If the internals of the ECU are good, then I would focus on the fuel lines from the pickup on the tank all the way to the pump. First, do an air test like I suggested above, if there is air, then logically and systematically test each line and replace as needed. I finally ended up replacing all the hard and soft lines with new, though the ultimate culprit was the pickup lines at the top of the tank where there is a bend to the soft lines.

If any of this is beyond your comfort levels, then I would try to find an old school diesel mechanics shop. The kind of guys that do not need a computer to tell them what to do, and can still logically troubleshoot and solve problems on their own.

 

[Jonesey]

Thanks for the reply. This is the pump that I ordered that did not match, (Diesel Fuel Injection Pump For Toyota 3.0L 1KZ-TE Prado Hilux HiAce 22100-67070 | eBay - https://www.ebay.com/itm/145354164161) which makes me think that it might not be a throttle actuated pump? This is the pump I am looking at trying next (Toyota Land Cruiser Prado Colorado Hilux 1KZ-TE Fuel Injection Pump 22100-67070 | eBay - https://www.ebay.com/itm/395442102147). It looks similar but I have not actually pulled the pump yet.

Thanks for the recommendation for the pump. I called them and once I can verify if it at least looks similar I will probably go with them.

Yes, guessing you have the electronic pump, not the mechanical (throttle actuated) one. Even without pulling it, you should be able to see if it has the (5) electrical connectors going to it and whether it has the throttle cable connection, or not. If you're able, recommend following the other advice you've gotten on here re: checking lines for air, etc. before going new pump route. Might be worth getting injectors out and having them bench tested/cleaned up/reconditioned at a diesel injection shop, as well. Find a PDF of your shop manual, should have specs for testing injectors - give that to the shop with the injectors. I am rebuilding my engine and just did this - injectors came back looking and spraying like new. Do not buy cheap/knock off injectors - recondition/rebuild the ones you have if they are Denso, or find some OEM Denso ones.

 

[Bad Mojo]

If the ECU looks good then I agree check fuel lines. I would suggest looking all the way back to the tank. And maybe a new fuel filter if you don't know the history of it. If you are unsure on how to swap it there is a 1KZ manual under the resources tab at the top of MUD. Also the very beginning of that manual has a diagnostics flow chart.

Also I keep coming back to the note about it having an issue right after filling the tank. I am wondering if the fuel has water in it.

As some have mentioned there is some value in doing the work yourself, but I get that may not be your thing. Once you have a copy of the factory service manual they are pretty simple trucks to work on especially if you aren't in a rush and have all the parts on hand.

 

[TAMF67]

Hi all,

Thank you for the valuable feedback. I have discussed most of this with the mechanic I am working with and have the following updates:

1. Fuel sample was taken (this was our first thought as well) and it was fine.
2. The fuel filter was replaced last August when this issue first came up and they adjusted the pump injection rate. It looked perfectly fine this time too.
3. The fuel lines were inspected and there was no blockage observed.
4. No noticeable air leaks.
5. ECU was squeaky clean.

I went to go pick it up today because apparently they were able to get it up and running and drove it in and out of the shop. However, once I hopped in to take it for a test drive as soon as I put it in drive and the engine came under load there was a bunch of sputtering, RPM fluctuations, and it started belching black/rancid smoke. In addition, the check engine light finally came on whereas it was not before. So we are back to square one. With the intermittency of the failures my thoughts are it has to either be the pump or something electrical. Finally, I was able to confirm that this Toyota Land Cruiser Prado Colorado Hilux 1KZ-TE Fuel Injection Pump 22100-67070 | eBay - https://www.ebay.com/itm/395442102147 is indeed the correct style pump.

 

[TAMF67]

Hi all,

Thank you for the valuable feedback. I have discussed most of this with the mechanic I am working with and have the following updates:

1. Fuel sample was taken (this was our first thought as well) and it was fine.
2. The fuel filter was replaced last August when this issue first came up and they adjusted the pump injection rate. It looked perfectly fine this time too.
3. The fuel lines were inspected and there was no blockage observed.
4. No noticeable air leaks.
5. ECU was squeaky clean.

I went to go pick it up today because apparently they were able to get it up and running and drove it in and out of the shop. However, once I hopped in to take it for a test drive as soon as I put it in drive and the engine came under load there was a bunch of sputtering, RPM fluctuations, and it started belching black/rancid smoke. In addition, the check engine light finally came on whereas it was not before. So we are back to square one. With the intermittency of the failures my thoughts are it has to either be the pump or something electrical. Finally, I was able to confirm that this Toyota Land Cruiser Prado Colorado Hilux 1KZ-TE Fuel Injection Pump 22100-67070 | eBay - https://www.ebay.com/itm/395442102147 is indeed the correct style pump.

Oh also the injectors were removed and cleaned when it was imported. I can see if a diesel shop nearby will do another test on them, but at this time the truck is non-drivable. Does anyone know of a diesel shop near Boston that is familiar with these style trucks?

 

[Bad Mojo]

This might sound funny, but I am glad a check engine light came on because at least the truck is starting to give a clue.

Take a look at post #11 it has the engine codes. It notes a process for pulling codes, but I believe it is for the newer Prados with 1KZs.
KZJ78 Engine Codes


And take a look at post #22 it walks you through how to jump the diagontics plug. The one in our truck is located next the batteries on the passenger side in the engine compartment. It isn't underneath the dash like an OBD port on a newer car.
KZJ78 Code Pull

 

[TAMF67]

Hi Everyone,

Reviving this thread because the issue has arisen again.

Long post ahead because I am just stumped and want to cover all my bases again.

 

[TAMF67]

Hi Everyone,

Reviving this thread because the issue has arisen again.

Long post ahead because I am just stumped and want to cover all my bases again.

Over the past two years of ownership with our 1994 KZJ78W-PET 1KZ-TE we have had multiple rounds of losses of power/sputtering/misfiring.

The first time it happened we were in Japan and the Japanese mechanic said they fixed it but to not run our A/C on the highest setting.

Then after we shipped it to the states another issue appeared, with limp mode activating above 2200 rpm. I adjusted the timing on the fuel pump, replaced the fuel filter and everything was fine for about 6 months highway included.

Then in June this past year, the sputtering and loss of power returned again! Adjusting the fuel pump did not work so we ended up replacing it with one ordered off eBay, and the truck ran fine again for about 3-4 months highway included.

Recently, we ran into the sputtering/misfiring and now the truck is struggling to even start up. I replaced the fuel filter and plastic portion at the bottom (was leaking), retimed the new pump again, did another oil change and the truck runs fine below 2200 rpm. However, above 2200 rpm or in a hill it enters limp mode again with a check engine light and code 14.

I’ve pulled the ECU multiple times (pictures attached), but overall it seems in amazing shape. Additionally I checked the wiring for the pump and I could not see any noticeable damage.

Is it worth paying for the ECU to have the capacitors replaced even if everything looks fine?

I am also going to replace the MAP sensor and filter as I saw another IH8MUD forum that

saw good results from that.

What else am I missing? There is another thread where someone replaced the timing control valve and everything worked perfectly but it just seems odd that both pumps would have the same issue.

Another logical step is to pull the injectors again I guess.

Thanks for everyone who reads this and is still willing to help!

 

[Eurasiaoverland]

Replacing your injection pump because of rough running is like replacing your axle because of a flat tyre.

When troubleshooting, you start with the simple, easy things and work up to the big, complex potential causes, rather than buying a new injection pump and taking your ECU apart.

So, have you bypassed the fuel tank/pipes/hoses/filter head to eliminate the possibility of air coming into the system? It's a very common cause of running problems. Just run a new piece of hose from a jar of clean diesel to the injection pump and see if the problem persists. You mention above 'no noticeable air leaks'. How did you test that? There can be pin-hole leaks in the fuel lines/hoses which let air in but do not leak diesel.

Have you tried to pull codes from the ECU? The next culprit would be one of the EFI sensors.

 

[TAMF67]

Replacing your injection pump because of rough running is like replacing your axle because of a flat tyre.

When troubleshooting, you start with the simple, easy things and work up to the big, complex potential causes, rather than buying a new injection pump and taking your ECU apart.

So, have you bypassed the fuel tank/pipes/hoses/filter head to eliminate the possibility of air coming into the system? It's a very common cause of running problems. Just run a new piece of hose from a jar of clean diesel to the injection pump and see if the problem persists. You mention above 'no noticeable air leaks'. How did you test that? There can be pin-hole leaks in the fuel lines/hoses which let air in but do not leak diesel.

Have you tried to pull codes from the ECU? The next culprit would be one of the EFI sensors.

Thanks for your reply!

I absolutely agree that we probably jumped the gun replacing the injection pump; however, we were following the 1KZ-TE Technical Manual for code 14 (pics attached), and the mechanic I took it too is known as one of the only techs in the area who can work on this old engines. Even so, I did ask the mechanic who was working on it if they tested the fuel system as one of the comments above recommended and they stated that they had (most likely did not).

I will give it a shot and report back! Even if this addresses the rough idling (which is gone now after replacing the leaking plastic portion at the bottom of the fuel filter), would that still be enough to trigger limp mode at 2200 rpm?