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80 Series starts but repeatedly cuts out - 4.5 petrol.

Paul D1963

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Nov 20, 2019
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great_britain
Hi all.

Took my 80 Series (24V petrol & LPG, 1996) off the road a couple of years ago to carry out some much needed restoration.

Came to move it a few months back with a view to putting it in the workshop to start the work. Probably hadn't been running for maybe 6 or 9 months prior to that, but it was running fine when last started. This time, however, it would start and then cut out after a couple of seconds, it would do this repeatedly, until eventually it wouldn't start at all. Leave it for a while, and then it would go through the same cycle.

I tried the emergency override to start directly on gas (this gas system has a feature that if you floor the throttle, it will start directly on gas instead of first starting on petrol before switching to gas after a short period), but that got similar results, which I guess rules out some elements of the fuel system.

I should add that, for the couple of seconds it does run, it sounds smooth and normal, just like a normal cold start. And when it cuts out, it does so very suddenly - it doesn't splutter and fade away like a fuel fault - it just dies instantly, as if the ignition had been cut. This leads me to believe it's electrical, but I'm at a loss to explain it.

Anyone had similar issues or any ideas as to what may be going on here? Any input would be much appreciated.
 
Open the aibox check there is nothing nesting in there or blocking it, try starting it with easy start or similar, see if it will run longer. Take out one of the spark plugs and see if is making a spark whilst cranking when it refuses to start.

Check the exhaust, are any fumes being pushed out whilst cranking, do they smell of fuel? If there is nothing coming out you may have a blockage or collapsed catalytic converter.

Has it been sat outside in the time you have been not using it?

The engine ecu is to the left and behind the glove box, check it has not got damp or wet, also the LPG ecu wiring will be connected to the main engine ecu wiring somewhere, these connections would also be a good place to check for damp/corrosion/poor connections. (I think the this is the place most likely to have the fault)

I have had this before on old Toyotas MR2's, it was the capacitors in the ECU leaking and shorting out the circuit card, they don't like being cranked over on low battery voltage when the capacitors are old, luckily its a cheap fix, clean up the circuit card and solder in some new capacitors.

Let us know how you get on and good luck!
 
Thanks for the suggestions Richard. I'll certainly look into some of those ideas.

Yes, it has been sat outside during its recent spell waiting for its turn in the workshop. I carried out the LPG conversion on it myself many years ago when I first bought it, and quickly realised that less than 20 to the gallon wasn't going to be liveable with!

The annoying thing is that it's been left outside for extended periods before, and has always started (with a battery charge) without any issues. Of course, I understand that's no guarantee of future performance, clearly, just as your broker will be keen to point out to you after he's lost all your money on dodgy 'investments'!

Anyway, will report back on my findings, but it may be a while until I can check it out again.
 
OK, yesterday I had another go at things, as I now want to get it into my workshop to begin the work on it. After another charge of the battery, the same thing was happening again - start and cut out, over and over. First thing I've tried to establish is whether it's ignition or fuel related. There is a spark, even when it won't start, and I've verified that when it dies after a couple of seconds, the sparks are still coming right up to the point the motor stops spinning, but after it's cut out if you understand what I mean. So I think it's a fuel problem.

So far, I've verified that the pump is running, and a check of the absolute pressure from the pump has given a figure over 80 psi, so I imagine that kind of proves the pump is delivering the goods. I haven't been able to test the actual system pressure due to not having a suitable adapter to splice into the line - and also the difficulty of getting to the incoming line where the vehicle is currently parked. The main EFI relay clicks as it's unplugged and plugged in again with ignition on, so that appears to be switching.

So, if we have fuel under pressure in the rail, and we have a spark, then the only thing to prevent it running is surely the injectors not being given the signal to open? Am I missing something? I should add that it now won't run at all - the starting and immediately cutting out has given way to now not even firing at all, it just spins over with no sign of life. I appreciate there's more to it than this, but if it was a faulty fuel pressure regulator, or a dodgy sensor somewhere, surely it would still run, but just roughly? I'm getting nothing at all now. There are no blockages or restrictions anywhere in the inlet tract, so it's not an air starvation issue. If there's pressurised fuel in the rail (there is) and a spark (yes), then the only thing preventing the fuel from getting to the spark is the injectors surely? And as all six couldn't fail simultaneously, then my thinking is they're not getting the signal to open.

One final thing to add: having read the codes, the only one I'm getting is 99, which research suggests is related to an immobiliser fault. Could the immobiliser be the culprit here? I know nothing about this. Does anyone know how the immobiliser prevents the engine from starting? I can only think of three ways it could do this:

1) It cuts the ignition circuit, so no spark.
2) It cuts the starter circuit, so no engagement of the starter.
3) It cuts the EFI somehow.

If it's 1 or 2, then that can't really be my problem - but if it's 3, then maybe?

Can anyone help me with this? I really can't even work on it properly where it currently sits, so I need to get it running so I can get it in the workshop. Too far to push and a little tight on space for towing it in there.

Any ideas will be much appreciated.
 
Some old style immobilisers would let the engine run a few seconds. It was probably an aftermarket fit back in the day. And the fact you can get a code for it kinda points in that direction.
 
Paul, make sure the MAS plug is plugged in properly, i.e. it is clipped in and tight and there is no water or corrosion in the plug itself. The cause of many starting/running problems on the FZJ80's.
 
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Thanks Dave. We are talking about the standard factory fitted immobiliser here, not an aftermarket one. It's activated and deactivated when you operate the central locking from the original Toyota remote fob. I wish it was an aftermarket one, as then I'd be able to unpick it from the wiring loom and completely remove it, but I have no idea if it's possible to remove, or even bypass, the built-in Toyota one. I suspect not, but if anyone knows otherwise, I'd be pleased to be wrong...
 
Thanks Olazz. By the MAS, are you talking about the unit that I would probably call an airflow meter: in the trunking between the air filter housing and the throttle body, has a plug with about five wires going into it? If that's the one, then I can say for sure that the clip on that plug is broken, and has been for years. But it's still a pretty tight fit in the socket, and I have already removed it to have a look at the connections inside - they look pretty clean and sound. I wanted to test the unit, but the only manual I have (a Haynes one) doesn't even mention it! Any ideas where I could get the test info for it?
 
Yep that's the one. Even though it's a tight fit, if the clip is broken, I'd cable tie it on. I had very similar problems with my fz and tried everything to solve the problem, till I found the plug was connected but not firmly enough. I clipped mine in and cable tied it on. It cured the problem and I've had no recurrence of the intermittent starting/running issues.
 
OK, thanks for the info - I'll certainly give that a try. Watch this space...
 
I'll second the air flow meter, mine has 2 cable ties holding the plug on tight after the clip broke, thought it was ok until it cut out on a green lane!

Does it smell of fuel when cranking, are the spark plugs wet? Will be a good indication the injectors are being switched, unless have access to an oscilloscope?
 
Thanks yet again all who've replied above.

Some further developments now. Subsequent to further tests on it today, and a lot more research, I've discovered a few things. First, I managed to get a copy of a Factory Service Manual, albeit a U.S. spec one - but most components appear to be the same as on mine. This has allowed me to test the MAF along with the IAC, fuel pump resistor and a couple of other bits. So far, everything has tested within spec.

However, I left the battery disconnected overnight, just to clear any glitches and also the codes. After reconnecting it today to do the aforementioned tests, I checked the codes again, and 99 is already stored, and it's the only one. Now, as mentioned previously, 99 I believe relates to an immobiliser fault. Having done a little more research, I understand it actually means 'immobiliser can't read key'. If that's true, then maybe this is the problem? My understanding is that the immobiliser computer 'reads' the key, and tells the ECM whether or not to allow the engine to start. This may account for why, at times, the engine will run for a couple of seconds, and at other times, there's nothing - it could simply be that the computer occasionally takes its time in deciding not to accept the key.

The vehicle has been left for an extended period, allowing the battery to go completely flat, and perhaps this has caused the problem. Probably would have been OK if the battery was disconnected, but allowing it to gradually discharge to the point of being totally flat may have caused it possibly? It's a computer at the end of the day, and I have certainly had problems with other devices that have computers and are battery operated - such as having to re-boot them if they've been left with a battery installed that's gone flat. But remove the battery before period of inactivity and the same device is OK when you come back to it. So maybe?

So, if this proves to be true, what I need to know is where to go from here? It's been suggested there may be some procedure I can do to enter a 'programming mode' to access the vehicle's immobiliser software to pair the key to the immobiliser, but so far I've only been able to find details for later models (OBD2 variants perhaps?). Also, it seems that for this to work, you need to have at least one key that still 'talks' to the immobiliser, and I don't. In which case, my only option may be to contact one of the automotive locksmith type companies who can access the car's systems to reset it. But if anyone knows of an operation I can try myself before going down that route, I'd be pleased to hear it. There may even be something in the original Land Cruiser handbook, but I don't have one - if anyone reading this has one, I'd really appreciate it if you'd have a look through and let me know if there's any info on this procedure.

Ever hopeful...!
 
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