6bt intermittent no start

Hi Guys. I am looking for some ideas of where to start looking for the cause of intermittent no start of our 6bt. It normally fires on first revolution of the engine, no accelerator required, and runs like a dream. Very occasionally, usually if trying to start the engine just after it has been shut down, it will turn over but will not fire up. If I leave it for 10 minutes and try again, it will start easily.
I was thinking maybe the fuel cutoff solenoid is stickng closed????
Any ideas much appreciated.
Cheers Tony

I do not see what else it could be?

As there are no butterfly (in a throttle body) and no spark plug... it somewhat reduces the variables compared to a petrol engine.

If it is turning over, then the only other thing is air and fuel assuming the compression is high.
As previously noted; there should not be much impeding the air from going in, so that leaves fuel.

Either the solenoid is:
1) no longer pushing hard enough when hot, or
2) when it is hot more push is required.

However any rubbish in the fuel can be bad... On a tractor, or similar engine, that usually results in an engine "bolting".

#2: I suppose any particles that may have gotten in could cause it to stick, or if the solenoid is 'tired' then being hot will increase resistance, and loose current flow, and therefore loose magnetic push.
I do not know what these look like on a 6BT... are there also some linkages and levers? of is it direct?

#1: I would likely put a volt meter on the solenoid to see what it is seeing for voltage. If the wire delivering the current is hot then the voltage drop will increase and that will also result in a lower slamming open of the solenoid... If it works at 12V, but not at 9 or 10V (or whatever), then you likely may need a new/fatter wire, or reroute it to keep it cooler. (I like Tefzel wire in general)

Hence I would do the volt meter first.

If it has a lever, then you could actuate by hand when hot and cold to get a feel for it. (or a spring scale or torque reading if you want to be precise). You may need some oven mitts...

Tony it appears to me like it is starving for fuel specially if you have to wait 10 min to re start,have a good look at all the fuel lines leading up to the filter and blow them clean ,it could be something partly obstructing the line causing a temporary vacumm,let us know what you find
Cheers,Joe

If you had a Landcruiser with a 1hz diesel engine I'd say that you had a worn injector pump. They also run a rotary IP and have the same physical symptoms when the pumps are worn, quite often from running one fuel tank until the engine starts to miss before changing tanks. The thirty seconds from when it starts to miss until it gets a new supply of fuel means that the IP hasn't had much lubrication or cooling for that period which causes excessive wear.
This leads to low IP fuel housing pressure as everything is hot and "loose" due to the wear, let it cool down for a while and away it goes. Unfortunately the only cure is a replacement IP. Wagga diesel used to resleeve the IP with bronze so they may be able to reco a VE pump.
Check all the obvious first like the stop solenoid etc but the big test for a worn IP is when it is hot and won't start dump a bucket of very cold water slowly over the IP to cool it quickly and then try starting it if it starts straight away when cooled rapidly then the IP is the culprit.
This of course does only apply if you have a VE rotary IP rather than an inline P IP.

Thanks guys for the helpful info.
Our previous vehicle was a landcruiser with a 1hz, with probably worn IP. It had instantaneous cold start, but needed a fair bit of cranking when hot. Our oka has the rotary IP, but behaves differently to the 1hz. The intermittent no start can be when the engine is hot or cold. The only consistant thing is that the no start occurs only when trying to start immediately after turning off the engine. I am hoping it is not the IP!
You all given me ideas on where to start looking. Will let you know how I go.
Tony

Tony,some how and just out of gut feeling I don't think the problem is the IP (it won't be the first time that i was wrong). If you have access to a vacuum hand pump check all the fuel lines from the tank to the pump and make sure that all lines are good and vacuum tight before you embark in expensive fixes if all check OK them you can get a really good bottle of Scotch and forget about the price of a IP overhaul
Cheers,Joe

Joseph Baz wrote: Tony,some how and just out of gut feeling I don't think the problem is the IP (it won't be the first time that i was wrong). If you have access to a vacuum hand pump check all the fuel lines from the tank to the pump and make sure that all lines are good and vacuum tight before you embark in expensive fixes if all check OK them you can get a really good bottle of Scotch and forget about the price of a IP overhaul
Cheers,Joe

Is there a lift pump on those engines?
It seems like it is either no getting fuel to the pump, or from the pump.

The solenoid idea, as well as Joe's words, both address fuel to the pump.

The 6bt has a diaphram lift pump. Mine has been set up with an electric pump as well. I have purchased and soon to fit a high volume low pressure piston pump, and also will scrap the electric pump. I will check all the fuel lines at the same time. That is the next job on the list. Thanks for all the ideas.

Problem now solved. I went thru the fuel system and ended up replacing all fuel hoses ( some were perished but no obvious leaks), both fuel filter housings and elements with higher flow rate "Fuel Manager" brand ones.New low pressure piston lift pump and removed electric one. Now she starts first turn of the key every time. Only problem is that I have not been able to pinpoint just where the problem was! Thanks for all the advice.
Tony

It is a good idea to check fuel pressure with the low pressure piston lift pump, sometimes they can push a bit high when the revs get up, the VE pump can't handle much more than about 12 psi safely, any more and you are likely to pop the front seal out and end up with diesel in the sump.