OBD11 fuel temperature check?

[T6 Syd]

Hi, not sure whether this is the correct forum, sort of between this and engine problems.

I have had the fuel temperature sensor conductor wear/break issue on my 2017 150 T6, confirmed by finding the broken conductor. Cured, or so I thought, by fitting a new connection plug (same as fuel injector plug) with leads. However, I occasionally get the flashing glowplug light and am unable to start the engine, typically after the engine has been run for a while and stopped then trying to start soon after. I have not (tempting fate) had it come on during a run, as it did with the conductor fault. Last time this happened I rechecked the connections and all appears fine, no wear at the plug yet and I have tried to set the conductors away from the pipes.

My query is whether or not heat is soaking to the fuel in the pipe when the engine has stopped, causing a 'true' high fuel temperature. I'm wondering because having checked the connections and changed the plug and wires for some sparest flashing glow plug light remained, but in desperation (ferry to catch) I resorted to cranking the engine and it eventually started. Did the cranking introduce cooler fuel?

Is that a possibility and is there a way of monitoring or checking the fuel temperature using OBD11? Could the sensor be faulty or out of calibration?

Thanks.

 

[DXX]

My query is whether or not heat is soaking to the fuel in the pipe when the engine has stopped, causing a 'true' high fuel temperature.

Your vans engine systems are laid out exactly the same as hundreds of thousands of others so unless there is some serious modification I’d say no there isn’t a problem with the fuel being heated by residual engine heat.

Bad Fuel Temperature Sensor: Signs & Symptoms | dubizzle

Do you know how fuel temperature sensors function and how to identify signs of its failure? Let’s find out some obvious symptoms.

www.dubizzle.com

 

[T6 Syd]

Thanks for the reply. No modifications and normal driving, so the next thing is can I check the operation of the sensor? I'm presuming I could disconnect it where I've connected the new leads to the old wires and measure the resistance, assuming it is that type of sensor. I would need to know what it should be at the temperature I'm checking it at. Or is it something I can get live data from using OBD11 do you know?

 

[DXX]

Thanks for the reply. No modifications and normal driving, so the next thing is can I check the operation of the sensor? I'm presuming I could disconnect it where I've connected the new leads to the old wires and measure the resistance, assuming it is that type of sensor. I would need to know what it should be at the temperature I'm checking it at. Or is it something I can get live data from using OBD11 do you know?

No idea with OBD11. You could check the sensor with a multimeter for continuity and leakage to ground (chassis). I have no idea what the resistance of a good sensor is but the pattern parts at least seem cheap.

 

[Gavinda]

If the sensor relies on varying resistance in relation to temperature, is it possible that your repair to the wire could have introduced a slight change in resistance?

 

[mmi]

Is that a possibility and is there a way of monitoring or checking the fuel temperature using OBD11?

OBDeleven ... Control Units > Engine > Live data > Fuel temp sensor 1 bank 1, raw value.

You could check the value before starting (cold) engine - should be close to ambient temperature.
For hot engine should be around 15-20 ℃ when outdoors +5..+10 ℃.

 

[T6 Syd]

Brilliant, thanks, will try to check it tomorrow - and when I next get the fault!

 

[T6 Syd]

@Gavinda - I did wonder that, though the sensor would have to have increasing resistance at increasing temp, otherwise a high resistance connection would lower the indicated temp.

@mmi - reading 10C at ambient 0C, parked overnight, engine not running. Running temp (at 3 to 4C ambient) indicated generally 28 to 30C, urban driving, dropped a bit driving uphill (more fuel flow?) and rose a bit when coasting. Check after being parked up for 1/2 hr (after 45 min urban drive) 45C.

Does the sensor just screw out from the pipe? Will look to get a replacement and check again.