1fz-fe dual fuel system question (1 Viewer)

[joshAUST]

Well, an update.
I installed a new genuine Crank angle sensor, and while it seems slightly smoother, it hasn't fixed my issue @99fzj105.
It seems to be smoother, and a little less likely to falter or hesitate, but it still nearly stalls, or backfires, with any real application of the accelerator.
It is running a tad better though, and its one thing to tick of from the list of possibles.

Gee, that photo you provided must have been of an engine that had been steam cleaned and sand-blasted!
I discovered mine has a leaking sump gasket, from the look of it, lots of oil over everything down low, especially on the RH side, near the crank angle sensor connector.
Another thing to fix, and as its due for a oil change might as well do that as well then.

I pulled all the plugs and inspected - they were all NGK BKR5EKB-11, which seem suitable.
They all seemed OK, not very worn, no fouled or blackened plugs.

I've ordered a cheap fuel pressure gauge which should turn up next week, so I'll check that.
If that's fine, I'll replace the fuel filter, and open up the old one to see if there's any rust or other crap in the tank.

Mine does seem to get worse the lower the tank is.
As its dual petrol and gas, I assume the sub tank has been removed, so I cannot test petrol performance on that tank.

The PO said it never worked for her on gas, and I haven't tried it, other than to see it die if I switch to gas - I decided to focus on getting it running OK on petrol well first...

Only other thing I noticed is that in the LH front sidewall, near the other relays and that, there is an aftermarket device to do with the dual fuel setup.
It has a dial/ potentiometer to adjust with a screwdriver, and has the words gas and petrol printed on either side.
Not sure what it does, or if it could affect the performance on petrol.

Anyway, I'll keep at it.

 

[99fzj105]

Well, an update.
I installed a new genuine Crank angle sensor, and while it seems slightly smoother, it hasn't fixed my issue @99fzj105.
It seems to be smoother, and a little less likely to falter or hesitate, but it still nearly stalls, or backfires, with any real application of the accelerator.
It is running a tad better though, and its one thing to tick of from the list of possibles.

Gee, that photo you provided must have been of an engine that had been steam cleaned and sand-blasted!
I discovered mine has a leaking sump gasket, from the look of it, lots of oil over everything down low, especially on the RH side, near the crank angle sensor connector.
Another thing to fix, and as its due for a oil change might as well do that as well then.

I pulled all the plugs and inspected - they were all NGK BKR5EKB-11, which seem suitable.
They all seemed OK, not very worn, no fouled or blackened plugs.

I've ordered a cheap fuel pressure gauge which should turn up next week, so I'll check that.
If that's fine, I'll replace the fuel filter, and open up the old one to see if there's any rust or other crap in the tank.

Mine does seem to get worse the lower the tank is.
As its dual petrol and gas, I assume the sub tank has been removed, so I cannot test petrol performance on that tank.

The PO said it never worked for her on gas, and I haven't tried it, other than to see it die if I switch to gas - I decided to focus on getting it running OK on petrol well first...

Only other thing I noticed is that in the LH front sidewall, near the other relays and that, there is an aftermarket device to do with the dual fuel setup.
It has a dial/ potentiometer to adjust with a screwdriver, and has the words gas and petrol printed on either side.
Not sure what it does, or if it could affect the performance on petrol.

Anyway, I'll keep at it.

Hi mate, thanks for the update it’s good to see what your up to, I’m just gonna say it outright - our model particularly (105) that have been run on gas at some point for an extended period of time seems to be one of the main reasons we have so many issues that are not exactly straight forward. I recently spoke with an auto mechanic that had been working with Toyotas for over 40 years and I really picked his brain and tried to get as much knowledge out of him as possible, and the end result of a 2 hour conversation was that Toyota engines, especially the 1fz should never have been put on gas and should have been kept to run on petrol only. Mainly due to the higher temperatures that gas creates, in his words it basically cooks the motors over time and puts big wear and damage on all the other sub components. Which totally does make sense, he says ‘they may run well on gas for 5 to 10 years but at the end of that run your going to be faced with a variety of different issues and be more than likely chasing them until you’ve done a complete engine overhaul, they just weren’t designed to be run on gas’ so take that for what it’s worth mate, bit of advice from an old Toyota guru.

I can’t remember if you said you have checked the MAF sensor? It’s on the intake manifold right next to the TPS sensor. If it is failing or failed it will make the engine run like crap, including backfires. Also pull the lid off your air box and inspect the whole inside of the box for cracks or cracked holes, if you find anything that is cracked on the plastic box housing then it has Likely had a back fire or 2 from the gas system, which in turn can cause havoc on the sensors. Sensors getting blasted with a backfire can do significant damage. Also worth replacing your TPS. As if it’s damaged the throttle position will be all over the shop and also will run like crap.

Good luck with it mate I still have my head in the engine bay almost everyday either sussing our potential issues or just generally getting my head around how these engines are setup etc

 

[joshAUST]

Hi mate, thanks for the update it’s good to see what your up to, I’m just gonna say it outright - our model particularly (105) that have been run on gas at some point for an extended period of time seems to be one of the main reasons we have so many issues that are not exactly straight forward. I recently spoke with an auto mechanic that had been working with Toyotas for over 40 years and I really picked his brain and tried to get as much knowledge out of him as possible, and the end result of a 2 hour conversation was that Toyota engines, especially the 1fz should never have been put on gas and should have been kept to run on petrol only. Mainly due to the higher temperatures that gas creates, in his words it basically cooks the motors over time and puts big wear and damage on all the other sub components. Which totally does make sense, he says ‘they may run well on gas for 5 to 10 years but at the end of that run your going to be faced with a variety of different issues and be more than likely chasing them until you’ve done a complete engine overhaul, they just weren’t designed to be run on gas’ so take that for what it’s worth mate, bit of advice from an old Toyota guru.

I can’t remember if you said you have checked the MAF sensor? It’s on the intake manifold right next to the TPS sensor. If it is failing or failed it will make the engine run like crap, including backfires. Also pull the lid off your air box and inspect the whole inside of the box for cracks or cracked holes, if you find anything that is cracked on the plastic box housing then it has Likely had a back fire or 2 from the gas system, which in turn can cause havoc on the sensors. Sensors getting blasted with a backfire can do significant damage. Also worth replacing your TPS. As if it’s damaged the throttle position will be all over the shop and also will run like crap.

Good luck with it mate I still have my head in the engine bay almost everyday either sussing our potential issues or just generally getting my head around how these engines are setup etc

 

[joshAUST]

Thanks @99fzj105.
I hope its not as you say... but yes, I have heard issues with dual fuel systems, in these, and other motors.
The 1FZ-Fe seems to run pretty hot anyway.
I'm hoping its not terminal... so I'll keep at it in the meantime.
The fact that it seems to run poorly especially when its low on fuel makes me think it could be crap in the tank, or an issue with the fuel pump?.
I should be able to pressure test the fuel rail next week hopefully.

I cant seem to find the MAF sensor. The only sensor at the air intake pipe that leads from the airbox to the mixer is a air intake temperature sensor.
Perhaps the 2002 FZJ105 doesn't have one?

 

[99fzj105]

Thanks @99fzj105.
I hope its not as you say... but yes, I have heard issues with dual fuel systems, in these, and other motors.
The 1FZ-Fe seems to run pretty hot anyway.
I'm hoping its not terminal... so I'll keep at it in the meantime.
The fact that it seems to run poorly especially when its low on fuel makes me think it could be crap in the tank, or an issue with the fuel pump?.
I should be able to pressure test the fuel rail next week hopefully.

I cant seem to find the MAF sensor. The only sensor at the air intake pipe that leads from the airbox to the mixer is a air intake temperature sensor.
Perhaps the 2002 FZJ105 doesn't have one?

Yes mate definitely keep at it I highly doubt it’s terminal, these motors are very robust. I will take a photo of the MAF sensor for you now. Also yes could very well be fuel related issue , I.e fuel pump, bad injector, crap in the tank. I am actually in the process of replacing the fuel system and I’m starting with the pump first.

 

[99fzj105]

The thing with the blue and silver sticker on it is the MAF sensor. 2x 10mm bolts and 1x vacuum hose on the bottom side of it.

 

[ppc]

Your picture does not show a MAF - Mass Airflow Sensor. What is shown is a MAP sensor - Manifold Absolute Pressure sensor.

Pressure versus flow.

 

[99fzj105]

Your picture does not show a MAF - Mass Airflow Sensor. What is shown is a MAP sensor - Manifold Absolute Pressure sensor.

Pressure versus flow.

Oh haha well there you go - that’s interesting thank you for that. It’s interesting that eBay where I bought it from had it listed as a MAF sensor.

 

[mudgudgeon]

It’s interesting that eBay where I bought it from had it listed as a MAF sensor.

Not surprising though. Treat most of what you read on eBay with suspicion.

The crank sensor from eBay, why do you think it's genuine?
Nothing in the listing you linked suggests it is.
Picture doesn't match OEM

A true genuine replacement would have cost you slightly more than half that via Partsouq

Price is USD$, So about $120 AUD, plus a bit of shipping

 

[99fzj105]

Not surprising though. Treat most of what you read on eBay with suspicion.

The crank sensor from eBay, why do you think it's genuine?
Nothing in the listing you linked suggests it is.
Picture doesn't match OEM

A true genuine replacement would have cost you slightly more than half that via Partsouq

View attachment 3334028View attachment 3334029
Price is USD$, So about $120 AUD, plus a bit of shipping

Not sure if your talking to me or josh, although I can assure you the crank sensor I purchased off eBay for $200 AUD . It’s a denso and is the genuine replacement part.

 

[joshAUST]

@99fzj105, thanks for the photos... I was looking at the other end, near the air box, where my old UZJ100 had the MAF sensor.
Mine only seems to have an ambient air temperature sensor there.
I'll have to check as per your photos to see if I can see it...although if its a MAP sensor and not a MAF sensor, perhaps that may not be relevant to the question?
Although, a super quick google of MAP symptoms do list fuel starvation, lack of power, etc so that may be have something to do with it.
And, actually looking at the second photo, I must have it, as I replaced that greeny coloured gas filter or whatchamacallit that is connected to the hose from that sensor.
Thanks again.
@ppc, thanks for clarifying which part it is.
@mudgudgeon, thanks also - yes, I normally get my parts from partsouq.com, as they are reasonably priced and seem to be all genuine.
Shipping is a bit expensive, but very fast, I usually get the part within a week.

Geez though, that MAP sensor isn't cheap!
$210 AUD plus shipping for genuine part....
Hmm, might try to work out how to test it first...

 

[mudgudgeon]

Not sure if your talking to me or josh, although I can assure you the crank sensor I purchased off eBay for $200 AUD . It’s a denso and is the genuine replacement part.

That's good. Photos looked a bit doubtful, and their description sure didn't make it clear.

 

[mudgudgeon]

@99fzj105, thanks for the photos... I was looking at the other end, near the air box, where my old UZJ100 had the MAF sensor.
Mine only seems to have an ambient air temperature sensor there.
I'll have to check as per your photos to see if I can see it...although if its a MAP sensor and not a MAF sensor, perhaps that may not be relevant to the question?
Although, a super quick google of MAP symptoms do list fuel starvation, lack of power, etc so that may be have something to do with it.
And, actually looking at the second photo, I must have it, as I replaced that greeny coloured gas filter or whatchamacallit that is connected to the hose from that sensor.
Thanks again.
@ppc, thanks for clarifying which part it is.
@mudgudgeon, thanks also - yes, I normally get my parts from partsouq.com, as they are reasonably priced and seem to be all genuine.
Shipping is a bit expensive, but very fast, I usually get the part within a week.

Geez though, that MAP sensor isn't cheap!
$210 AUD plus shipping for genuine part....
Hmm, might try to work out how to test it first...

Partsouq regularly gets stuff to me faster than a local Toyota dealer in Sydney can.
They carry less and less stock. Everything comes from a warehouse in Melbourne, or 3 weeks out of Japan

 

[joshAUST]

Well I'll be....
I was about to order a replacement MAP sensor, but thought I'd change the vacuum line to it first.
The one that goes to that small greenish gas filter, that I had recently replaced.
I also replaced the vacuum line that runs between the fuel regulator and the throttle body near the throttle position sensor.
The car seems to be running so much better!
Smother idle, better acceleration and power, less hesitation, no backfires...

Not 100% yet, but actually drive able now.

The PO had a lot of receipts over the last 3 years for work done, and no mention of spark plugs being replaced, so I might change them over.
Then fix the muffler, as it sounds like a tractor.
Hopefully doing those two might improve performance a bit more.

I am pretty sure I still have a fuel issue, so will pressure test it when my test gauge turns up, and will have to wait a bit to run the tank down to low and see what happens.
Thanks @99fzj105, and everyone else, for your help and advise.

 

[99fzj105]

Well I'll be....
I was about to order a replacement MAP sensor, but thought I'd change the vacuum line to it first.
The one that goes to that small greenish gas filter, that I had recently replaced.
I also replaced the vacuum line that runs between the fuel regulator and the throttle body near the throttle position sensor.
The car seems to be running so much better!
Smother idle, better acceleration and power, less hesitation, no backfires...

Not 100% yet, but actually drive able now.

The PO had a lot of receipts over the last 3 years for work done, and no mention of spark plugs being replaced, so I might change them over.
Then fix the muffler, as it sounds like a tractor.
Hopefully doing those two might improve performance a bit more.

I am pretty sure I still have a fuel issue, so will pressure test it when my test gauge turns up, and will have to wait a bit to run the tank down to low and see what happens.
Thanks @99fzj105, and everyone else, for your help and advise.

Sounds like your onto a winner mate good to hear your being persistent and getting things sorted out! keep me posted!

 

[AussieHJCruza]

Have a look at the spark plugs, I've often found that trucks that have been run on gas have a colder plug than factory recommended. If you're not an LPG fan, put the proper heat-range plug in and enjoy better (marginally) performance and in my experience, better fuel economy.

 

[joshAUST]

Just another (late) update, for what its worth.
I replaced the spark plugs with ones suitable for LPG and petrol, as I would like to get the LPG going one day.
I also replaced a few hoses.

Still haven't replaced the leads or coils yet.

Then I replaced the fuel filter... and wow, so much rust!
I poured the contents into a coke bottle.
It was filled with rust, and was a dark brown colour.

I replaced the filter and immediately had lots more power, but its gradually going back to worse a month or so later...
I've bought a second hand replacement main and sub tank, and will install them soon-ish.
My sub tank has never worked since I got it, so I guess I'll replace that as well, and get a new pump for it as well probably.

The main came with its own fuel pump still attached, so I think I'll remove it, test it, clean and inspect the tank, and then use it instead of the current one.
Then see about getting the injectors cleaned.
I'll update when I can.

 

[99fzj105]

Just another (late) update, for what its worth.
I replaced the spark plugs with ones suitable for LPG and petrol, as I would like to get the LPG going one day.
I also replaced a few hoses.

Still haven't replaced the leads or coils yet.

Then I replaced the fuel filter... and wow, so much rust!
I poured the contents into a coke bottle.
It was filled with rust, and was a dark brown colour.

I replaced the filter and immediately had lots more power, but its gradually going back to worse a month or so later...
I've bought a second hand replacement main and sub tank, and will install them soon-ish.
My sub tank has never worked since I got it, so I guess I'll replace that as well, and get a new pump for it as well probably.

The main came with its own fuel pump still attached, so I think I'll remove it, test it, clean and inspect the tank, and then use it instead of the current one.
Then see about getting the injectors cleaned.
I'll update when I can.

Thanks for your updates Josh it’s always good to hear anything like what your doing in relation to the 105. I’ve only just gotten on top of all my issues (touch wood) as of the last month. It’s takin a good 6 months to square away all the oil leaks and annoying little issues I was having. It’s interesting what you say about the fuel filter, can I ask you for a quick tutorial on how you changed the fuel filter as I would love to do this also

 

[joshAUST]

Sorry @99fzj105, I didn't actually do the change over myself.
My brother in law did it for me.
I didn't watch him, but he said it was fairly straight forward, the main issue was the limited space due to the gas mixer being above/near it.
There is a video on Youtube that is meant to show it, but may be overly complicated, as I do not think you need to jack the car up or remove a tyre, etc.
I'm sure my brother in law did it from the top.
I think you are meant to have a special tool to undo one hose, on the engine side of the filter, but he removed it without the tool.
If I speak to him soon, I'll ask him how he undid it.

I'll post the youtube link anyway, in case it helps, however it did look a bit different connectors to my 2002 105 series.


If you do find a heap of reddish brown rust, I'd run the tank low, then try draining it. Both main and sub have a small drain plug underneath.
If its rusty, there are videos on fixing the rust, but most require removing the tank, and the pumps, cleaning, then swirling around a treatment inside, then reinstalling.
Sounds like a headache...
Glad to hear you've got on top of your issues.
I'll slowly work through mine and update if I find something of note.

 

[99fzj105]

Sorry @99fzj105, I didn't actually do the change over myself.
My brother in law did it for me.
I didn't watch him, but he said it was fairly straight forward, the main issue was the limited space due to the gas mixer being above/near it.
There is a video on Youtube that is meant to show it, but may be overly complicated, as I do not think you need to jack the car up or remove a tyre, etc.
I'm sure my brother in law did it from the top.
I think you are meant to have a special tool to undo one hose, on the engine side of the filter, but he removed it without the tool.
If I speak to him soon, I'll ask him how he undid it.

I'll post the youtube link anyway, in case it helps, however it did look a bit different connectors to my 2002 105 series.


If you do find a heap of reddish brown rust, I'd run the tank low, then try draining it. Both main and sub have a small drain plug underneath.
If its rusty, there are videos on fixing the rust, but most require removing the tank, and the pumps, cleaning, then swirling around a treatment inside, then reinstalling.
Sounds like a headache...
Glad to hear you've got on top of your issues.
I'll slowly work through mine and update if I find something of note.

No worries Josh thanks for your in depth reply ! And yes sounds good mate look forward to hearing more. I’ll let you know how I go with fuel filter replacement