Jet fuel in a 1kz?

[Wolf Suit]

Hi everyone,

So this is a bit long winded, but you’ll be saving my ass if you can help me out.

I work in aviation and have access to free jet fuel and with the cost of fuel these days, I took to using it. My coworkers and I have been using it for years in other diesels we’ve owned without issue. My KZJ78 with a 1KZ-TE however does not seem to like it. It actually seems to RUN fine with no observable difference in power, temperature or smoke or anything. The issue is starting. It starts beautifully with diesel and RUNS fine with either, but it has been dragging on starts with jet.

I do use Stanadyne lubricity formula with the jet fuel when I run it. I have changed the glow plugs, I’ve had the injectors professionally rebuilt and tested. I’ve replaced my fuel filter and my air filter. I’ve got a brand new battery. I’ve tested (and re-terminated one lead) on my fusable link. I’ve pulled the ECU to have a look and it appears fine with no signs of blown capacitors or burnt resistors. I (slightly) adjusted the spill control valve to enrich it, hoping that it would add pressure at the injectors and atomize the fuel better. The pump on the fuel filter stays firm, suggesting that I’m not losing prime. I’ve jumpered pins TE1 and E1 to read engine codes and my check engine light just flashes constantly.

All I can think is that it has something to do with the viscosity of Jet fuel as it is a fair bit thinner.

Currently it won’t fire AT ALL. It’s completely dead and causing me a ton of stress. It was running fine, but I left the lights on one day and killed the battery. I jumped it and all was fine for a few days. Then it was clear that the battery was completely DEAD. So I replaced it and everything was fine. It ran for a few more days (usual sluggish starts, but after that no issue) and then just refused to fire completely. It cranks, but won’t fire. I was planning on going back to diesel once I’d burned through this tank, but I never got the chance.

The two ideas I have are either to add in a boost pump (maybe the pump is having difficulty building pressure on start up due to reduced viscosity?) or replacing/rebuilding the pump (obviously not cheap).

Interestingly enough, another guy I know in the industry with a Hilux with the same engine is having the same issues. He’s even tried a 50/50 mix with the similar slightly improved) results.

I know jet fuel is dry and harder on pumps but I’ve got guys I work with who have been using it in their vehicles for the last 15-20 years and it should be fine so long as you’re using adequate lubricity additive.

At this point I don’t even really care about using jet fuel. I’ll use diesel if I need to, I just need to get this thing running.

Please help.

 

[Dprio34]

@Wolf Suit , sorry to hear about your problem. I would have definitely been tempted, as well, to put free fuel in my truck. My understanding is, it probably would have been OK, on the diesels built 25 years ago, but with the new "super low sulfur" fuel standard combined with IDI, maybe not. You have tested the injectors and replaced most everything else but the Injection Pump. As you stated, Jet A and A1 are hard on injection pumps and injectors due to lubrication or there lack off. Evidence seems to point toward the IP as the culprit. Keep us posted, hope you can get it sorted w/o having to rebuild the pump.

 

[Wolf Suit]

@Wolf Suit , sorry to hear about your problem. I would have definitely been tempted, as well, to put free fuel in my truck. My understanding is, it probably would have been OK, on the diesels built 25 years ago, but with the new "super low sulfur" fuel standard combined with IDI, maybe not. You have tested the injectors and replaced most everything else but the Injection Pump. As you stated, Jet A and A1 are hard on injection pumps and injectors due to lubrication or there lack off. Evidence seems to point toward the IP as the culprit. Keep us posted, hope you can get it sorted w/o having to rebuild the pump.

This is a ‘94 so the era should not be the issue. Also, I may have forgotten a significant point. After I put the new battery in, it ran for a day or two just fine, then I went to start up (and maybe turned the key to fast) and all power was gone. The lights came on for a split second and then once I turned to the actual ignition, all power disappeared and would not come back. That’s when I pulled the ECU initially. Nothing seemed off about it so I put it back in and voila! Power was good again despite me not having changed anything. Now however it still won’t start, despite power being restored.

 

[Felde]

Hi
You need to separate any electrical issue from the issue of 'engine doesn't fire'.
Sort out your electrics first: Make sure you have proper glow and crank.

I assume there is no reason why timing or any other engine setting could be off?

Check your fuel line prime. Maybe the thinner viscosity causes an issue there. Actuate the priming pump / bleed the fuelline- furlfilter before attempting a start. Make sure there is juice.

Disconnect the fuel line from the tank and feed it clean diesel from a jerrycan.

If it still doesn't fire: Crack the injector lines and make sure there is juice. Maybe have it spill some fuel until you have diesel at the injector.

If it still still doesn't fire: Do a compression test and assess engine settings.

Going for the IP would be my last resort.
Good Luck Ralf

 

[Wolf Suit]

Hi
You need to separate any electrical issue from the issue of 'engine doesn't fire'.
Sort out your electrics first: Make sure you have proper glow and crank.

I assume there is no reason why timing or any other engine setting could be off?

Check your fuel line prime. Maybe the thinner viscosity causes an issue there. Actuate the priming pump / bleed the fuelline- furlfilter before attempting a start. Make sure there is juice.

Disconnect the fuel line from the tank and feed it clean diesel from a jerrycan.

If it still doesn't fire: Crack the injector lines and make sure there is juice. Maybe have it spill some fuel until you have diesel at the injector.

If it still still doesn't fire: Do a compression test and assess engine settings.

Going for the IP would be my last resort.
Good Luck Ralf

Thanks for that. I never thought to disconnect the fuel line and run it straight from a jerry can. Good thought. I’ll do that and report back.

 

[OGBeno]

This might the funniest thread I’ve read in a long time.

What are these “other diesels” you and your compatriots have run jet fuel in? And when you say Jet Fuel you are speaking AvGas for commercial jet liners? Prop aircraft? Fighter jets? Piston aircraft?

A 1KZ-TE is already a shït engine. I have a feeling it didn’t like jet fuel.

 

[Wolf Suit]

This might the funniest thread I’ve read in a long time.

What are these “other diesels” you and your compatriots have run jet fuel in? And when you say Jet Fuel you are speaking AvGas for commercial jet liners? Prop aircraft? Fighter jets? Piston aircraft?

A 1KZ-TE is already a shït engine. I have a feeling it didn’t like jet fuel.

The fan favourite has been VW Jetta’s, but a number of Dodge Ram’s, Ford F150’s and most recently, the BMW X5. This is Jet A for a turbine. Can’t help but feel there’s some cynicism there. Just cause you don’t know of something, doesn’t mean it doesn’t exist. It’s a shockingly common occurrence in aviation. Fuel control is understandably high priority in aviation, but once it’s removed from the aircraft for inspection/diagnostic purposes, that quality control is gone and it’s essentially useless. People pay big money to have it properly disposed of. OR we can use it in our cars. So if you’ve got some constructive thoughts or suggestions, I’d be super appreciative as that’s kinda the whole point of these forums. If however, you’ve just come on to take shots at something you don’t know about and tell me what a pile of s*** my truck is, then next time just don’t.

 

[JuanJ]

Hello,

By jet fuel, do you mean JP-1 or similar?

There is a little difference in the flash point between diesel and jet fuel. There are differences in viscosity and other properties as well.

In principle, jet fuel burns like diesel does. Reality is a tad different.

Some injection pumps require diesel that is a little more viscous to operate properly. Differences in viscosity imply variations in flow and lubrication properties, among other things. A different flash point affects proper combustion inside cylinders.

Some diesel engines are designed for variable quality fuel, some are not. The 1KZ engine is a bit sensitive.

As @Felde mentioned, it is better to sort out fueling and electrical issues first.

If you have access to analysis reports for the jet fuel, it is worth comparing them to diesel properties. You can also send a sample for analysis. If viscosity is less than diesel, it is wise to run a viscosity modifier.






Juan

 

[OGBeno]

The fan favourite has been VW Jetta’s, but a number of Dodge Ram’s, Ford F150’s and most recently, the BMW X5. This is Jet A for a turbine. Can’t help but feel there’s some cynicism there. Just cause you don’t know of something, doesn’t mean it doesn’t exist. It’s a shockingly common occurrence in aviation. Fuel control is understandably high priority in aviation, but once it’s removed from the aircraft for inspection/diagnostic purposes, that quality control is gone and it’s essentially useless. People pay big money to have it properly disposed of. OR we can use it in our cars. So if you’ve got some constructive thoughts or suggestions, I’d be super appreciative as that’s kinda the whole point of these forums. If however, you’ve just come on to take shots at something you don’t know about and tell me what a pile of s*** my truck is, then next time just don’t.

I think you misread the internets today with my commentary. It has nothing to do with YOU AS A PERSON.

It has everything to do with the structural reality of the context you provided. Ergo, yeah I’m going to laugh. Your choice would literally have been the last choice with a JDM truck.

I said it was funny because the last thing I would do with these awful, old JDM engines would be to put a fuel that the computer would go haywire over, or more importantly was not able to consume.

1KZ-TE is a shĩt engine in the Toyota form. A number of adherents here have been able to make the -TE iteration work. But they have spent metric shĩt tons of money to do so.

I have 3 -TE engine swaps coming up this year. There are better engine options.

And, in terms of being upset with my commentary, you are in a public forum: think of it as a bar: we are talking and you tell me what you did and I laugh and I retort.

So don’t tell me to say “something constructive”.

You are in the public sphere. Act accordingly as I do. I’ll laugh if I want to and I will have conversation with you as well.

Don’t make criticism mutually exclusive.

 

[Wolf Suit]

I think you misread the internets today with my commentary. It has nothing to do with YOU AS A PERSON.

It has everything to do with the structural reality of the context you provided. Ergo, yeah I’m going to laugh. Your choice would literally have been the last choice with a JDM truck.

I said it was funny because the last thing I would do with these awful, old JDM engines would be to put a fuel that the computer would go haywire over, or more importantly was not able to consume.

1KZ-TE is a shĩt engine in the Toyota form. A number of adherents here have been able to make the -TE iteration work. But they have spent metric shĩt tons of money to do so.

I have 3 -TE engine swaps coming up this year. There are better engine options.

And, in terms of being upset with my commentary, you are in a public forum: think of it as a bar: we are talking and you tell me what you did and I laugh and I retort.

So don’t tell me to say “something constructive”.

You are in the public sphere. Act accordingly as I do. I’ll laugh if I want to and I will have conversation with you as well.

Don’t make criticism mutually exclusive.

That’s nice.

 

[OGBeno]

That’s nice.

Gojira would agree.

 

[Wolf Suit]

Hello,

By jet fuel, do you mean JP-1 or similar?

There is a little difference in the flash point between diesel and jet fuel. There are differences in viscosity and other properties as well.

In principle, jet fuel burns like diesel does. Reality is a tad different.

Some injection pumps require diesel that is a little more viscous to operate properly. Differences in viscosity imply variations in flow and lubrication properties, among other things. A different flash point affects proper combustion inside cylinders.

Some diesel engines are designed for variable quality fuel, some are not. The 1KZ engine is a bit sensitive.

As @Felde mentioned, it is better to sort out fueling and electrical issues first.

If you have access to analysis reports for the jet fuel, it is worth comparing them to diesel properties. You can also send a sample for analysis. If viscosity is less than diesel, it is wise to run a viscosity modifier.






Juan

There’s a bit to chew on there.

So for starters, it’s Jet A. I’m aware of both the reduced cetane value and the reduced viscosity.

My thinking is that the cetane value is not the issue as I’m pretty sure I’d see other performance issues, although maybe I’m wrong.

I do know that I have some blow by, which I’m sure isn’t helping. However, the other guy I know that has the 1KZ just rebuilt his entire engine and has no blow by at all and is still having the same behaviour.

I really think the viscosity is the issue. I’ve never heard of viscosity modifiers. I’ll look into that. In the meantime, I’m going to Felde’s advice and try and purge the lines and run it from a jerry can. You’re both absolutely right that I need to separate fuel from electrical and this seems like the best first step.

Thanks.

 

[JuanJ]

There’s a bit to chew on there.

So for starters, it’s Jet A. I’m aware of both the reduced cetane value and the reduced viscosity.

My thinking is that the cetane value is not the issue as I’m pretty sure I’d see other performance issues, although maybe I’m wrong.

I do know that I have some blow by, which I’m sure isn’t helping. However, the other guy I know that has the 1KZ just rebuilt his entire engine and has no blow by at all and is still having the same behaviour.

I really think the viscosity is the issue. I’ve never heard of viscosity modifiers. I’ll look into that. In the meantime, I’m going to Felde’s advice and try and purge the lines and run it from a jerry can. You’re both absolutely right that I need to separate fuel from electrical and this seems like the best first step.

Thanks.

Hello,

I just noticed the fuel is Jet A. Its flash point is different than diesel. On some engines it may be enough to make the ECU go haywire.

It is worth getting a sample and having it analyzed for flash point and viscosity.






Juan

 

[mongoose2231]

Wait, didn't the kz run just dandy on normal diesel? It only acts up when using jet fuel. Am I missing something? I think the problem is obvious, no?

 

[Pighead]

So if you’ve got some constructive thoughts or suggestions, I’d be super appreciative as that’s kinda the whole point of these forums. If however, you’ve just come on to take shots at something you don’t know about and tell me what a pile of s*** my truck is, then next time just don’t.

So, "If you've got nothing nice to say don't say nothing at all"? Finally, someone figures out the whole point of 'Mud. I got a POS engine too, runs very poorly on jet fuel so I don't use it if I don't have to. Easy fix.

 

[Wolf Suit]

Wait, didn't the kz run just dandy on normal diesel? It only acts up when using jet fuel. Am I missing something? I think the problem is obvious.

Yes it runs fine on diesel and RUNS fine on jet. It only has issues STARTING on jet. If you’re going to say that the problem is the jet fuel, then yeah, I suppose what’s going on is obvious but you may not understand the predicament. It won’t start at all now fo starters, but on top of that, I want to run it if I can as it’s free for me. If the solution is obvious, then I’m an idiot and there’s a good chance of that either way.

 

[mongoose2231]

I think we all understand that you are trying to get it to start on jet just as it did on regular diesel. What we are trying to point out is that there may not be a solution to that, since you have just about replaced everything you could have to try and mitigate. I'd say, easiest solution is to set it up where it starts on diesel and then runs on jet. Basically a dual tank or something, like running cooking oil.

 

[Wolf Suit]

I think we all understand that you are trying to get it to start on jet just as it did on regular diesel. What we are trying to point out is that there may not be a solution to that, since you have just about replaced everything you could have to try and mitigate. I'd say, easiest solution is to set it up where it starts on diesel and then runs on jet. Basically a dual tank or something, like running cooking oil.

Yeah, that’s been suggested by a friend. Could be a bit of cash up front, but the savings in the long run will more than make up for it. I’m gonna try a few more things first, but that’s definitely on the table.

 

[Wolf Suit]

So, "If you've got nothing nice to say don't say nothing at all"? Finally, someone figures out the whole point of 'Mud. I got a POS engine too, runs very poorly on jet fuel so I don't use it if I don't have to. Easy fix.

Which engine have you tried jet in? I’m curious which work and which don’t.

 

[javelinadave]

Which engine have you tried jet in? I’m curious which work and which don’t.

JP4 runs great in all mechanical (Non ECU) Land Rover diesel motors
11J thru 15J
19J
200Tdi
300Tdi