Non Starting Diesel on cold mornings but FBH works

[smallheathlad]

Originally Posted by HarryM1BYT

Do an injector leak back test. Assuming the battery and starter crank it over fast enough, it is often the cause of difficult starting. A quick means to check for it, is to squirt some easy start, into the intake. If it starts then, it is almost certainly leak back. Leak back, is fuel is being leaked by a leaking faulty injector and returned to the fuel tank, so no obvious leakage. If the leakage is too much, fuel pressure will be lost and it refuses to start.

The definitive test, is to measure the amount of fuel leaking from each injector over a set period of time. They all do have some leakage past the injectors, all the time, that is normal, but too much and no start. Once it starts, the flow is much greater, so a small amount of leakage makes no difference.

Glow plugs are not usually needed, except in extremes - we are still far from those extremes of cold which need them.

Likewise the FBH working is not necessary to starting, rather it is there for your comfort and to reduce cold running time once started, maybe save fuel.

Many thanks for the info and suggestions most helpful.
the point I was trying to make about the fbh was when used to get heat into engine will start even if below freezing. For example tonight air temp -4, engine stone cold will not start. Ran FBH temp for 20 mins (therefore assume fuel pump is working)using onboard diagnostic water temp is 22c crank engine after 4 seconds engine starts with accelerator pressed down.

How does one carry out a leak back test? I’ve only been able to find a simple video on YouTube which was in French which is not that helpful.

Will try the easy start, I guess it’s a 2 person task ie operating the key while someone squirts easystart into the intake.?

Do appreciate your advice along with comments.

[smallheathlad]

Will try that out, thanks

[HarryM1BYT]

Originally Posted by smallheathlad

Many thanks for the info and suggestions most helpful.
the point I was trying to make about the fbh was when used to get heat into engine will start even if below freezing. For example tonight air temp -4, engine stone cold will not start. Ran FBH temp for 20 mins (therefore assume fuel pump is working)using onboard diagnostic water temp is 22c crank engine after 4 seconds engine starts with accelerator pressed down.

How does one carry out a leak back test? I’ve only been able to find a simple video on YouTube which was in French which is not that helpful.

Will try the easy start, I guess it’s a 2 person task ie operating the key while someone squirts easystart into the intake.?

Do appreciate your advice along with comments.

It helps if there are two, but can just about be done with one with the easy start.

An FBH pre-warmed engine, will crank over a little faster and the extra speed might be enough to make the difference. None the less it should start even in the coldest weather, without the FBH - mine does.

Testing the leak back, is a matter of taking the leak back pipe off the injectors in turn and simply measuring the CC's over a period of time, each one against the other three. The leak back pipe is a soft flexible one, the feed is an extremely high pressure one in steel, with each leak back pipe T'ed together to return surplus fuel back to the tank.

[sewerman]

Originally Posted by smallheathlad

Many thanks for the info and suggestions most helpful.
the point I was trying to make about the fbh was when used to get heat into engine will start even if below freezing. For example tonight air temp -4, engine stone cold will not start. Ran FBH temp for 20 mins (therefore assume fuel pump is working)using onboard diagnostic water temp is 22c crank engine after 4 seconds engine starts with accelerator pressed down.

How does one carry out a leak back test? I’ve only been able to find a simple video on YouTube which was in French which is not that helpful.

Will try the easy start, I guess it’s a 2 person task ie operating the key while someone squirts easystart into the intake.?

Do appreciate your advice along with comments.

Just to be clear the FBH uses is own separate dosing pump and if you have let it run for 20mins and its only getting the temp to 22c its not doing it job at all well after 20mins at -4 my obd says between 71-77c which is were it should be

[HarryM1BYT]

Originally Posted by sewerman

Just to be clear the FBH uses is own separate dosing pump and if you have let it run for 20mins and its only getting the temp to 22c its not doing it job at all well after 20mins at -4 my obd says between 71-77c which is were it should be

That is true, unless the coolant thermostat is opening early, or passing. Either situation means heated coolant will be flowing into the radiator and a great deal of the heat will then be lost to the air.