3.0 D4D will not start when hot

[Bob]

I've only managed to make mine not start on 2 occasions, and both times intentionally sort of.. to my mind they are the only 2 ways it won't start if the engine runs fine up to that point.. immobiliser (I tried a cut key without the chip- turns over but no fire) or fuel (after a new diesel filter before priming just for the hell of it)

I've been thinking about it for the last few hours and coming up with nothing else that could explain it. My though process based on whats needed to make a diesel engine work is below -

Start stream of consciousness...

Air- unaffected by temperature bar being less efficient
Battery - couldn't be affected by engine block temperature
Starter motor - likewise.. if it starts cold, surely it can turn it warm
Diesel delivery - why only when hot?
Diesel pump - leaking back is common on old inline mechanical pumps I work on with tractors, but with the pressure from a common rail system I'm not as sure about how it happens. Electronic SCVs can be problematic after plenty of miles, but haven't seen them prevent starting, more developing a 'flat spot' in the rev range.
Injectors: thermal expansion causing an issue? I'm not a metallurgist or a diesel wizard so it may be possible, but I'd have my doubts
I would like a cheese sandwich...
Immobiliser- how does engine temperature possibly affect this...
Cooling system - is there a cooling problem with the rad that's making it run hot, and do Toyota have a hidden sensor that won't allow it to start if water temps are above a certain temp? There's not that many sensors on the KD unit... so I don't think so but maybe someone else knows
Now, where's that cheese?

...end stream...

 

[Shayne]

A dirty throttle body is the only thing i can think of that might change with hot and cold , we know egr and crank gas tend to clog things up with carbon which may not be much of a bother when cold but hot its wet and perhaps sticky ?

 

[goodoldboy]

My thoughts are that it could be a dry joint on PCB , bad earth or some other electrical/electronic gremlins IF ambient temperature isn't having an effect.
So maybe something in the engine bay affected by temps ? does this rule out ECUs & components in the cabin like the immobiliser ?
Stick a fan heater in the cab & crank it up , see what happens ?

 

[Chris]

What I have not been able to observe is how long (between stopping the engine and restarting, when hot) it takes NOT to start. If it was stopped and the key turned immediately - 5 mins, 10 mins etc. ??? He just stays it won't start when it's been left but is hot. To resolve his issue, I need more intel. But he does say with someone pumping the primer it will start.

Hmm, let me think. Fuel supply issue??

 

[JohnnyB]

Yeah that sounds like a fuel issue. And I think the immobiliser might be a good place to start for me. I'm wondering if there are some bad connections somewhere.

Thanks for the help guys

 

[goodoldboy]

But he does say with someone pumping the primer it will start.

Vital new info that seems to rule out electrical woes .

 

[Iwan]

Crank sensor in the front timing gear cover can fail and renders the vehicle useless.?. a bit like an abs sensor in the wheel hub?..

 

[DiamondDriller]

Either Fuel pump (old diesel) - when worn out and the fuel is warm it is less viscous so the weak pump dont pump good and loses prime.
Injection sensor - When cold sprays a ton of fuel for startup, but if its dirty or damaged (reading cold when WARM) it over fuels and you will not be able to start.

this happens to our gennys and small diesels at work ( i work in the arctic and all over canada) we just bring them in to the shop and they usually run a cleaner through them, or just replace...... i guess it really gets hot and cold here with more ware and tare?

my 2 cents!

Good luck

 

[Trevor]

Another random one to add, I had issues with a faulty oil pressure sender on a 1KZT. It would crank alright but not fire.

Given its bolted into the block, its possible (maybe) that if its going faulty its only showing up after heating up.

 

[Michael80]

I think I would just give it a little sniff of easy start when it doesn't start, if it starts up its a fuel problem. Could be caused by an injector giving a low rail pressure?
Can you check the leak off amounts on the injectors?

 

[stuzbot]

Starter motor - likewise.. if it starts cold, surely it can turn it warm

At the danger of offering an outsider point of view [Lurking here for a while, but not got a LandCruiser yet]...

I had a similar problem on my VW T3 Syncro. It would start first turn of the key when cold, but would take several seconds cranking when warm, before starting. So not quite as bad as the OP --it would start eventually!

Let it cool down for 20-30 minutes or so and it was back to starting first turn of the key again. After trying various potential solutions related to fuel delivery, glowplug relay, wiring, earths etc., I eventually changed the starter motor and the problem was gone.

I'm sure that isn't the cause here. But, just in case anyone else sees this thread; know that it is possible to have a reluctant hot start caused by a faulty starter --even though common sense would suggest a starter motor has to work harder, turning over a cold engine than a hot one.

But those electrical gremlins are no respecters of logic!