hi all
im have been looking at the fuel usage and I am some what stuck.
My Truck( MAN ) has telemetric’s and using this to provide how much fuel we have used over a 9 week period has shown a difference of 786.20 litres , truck is showing 5981.01 litres used, how ever the fuel drawn from the pump ( Fuel cards) is 6768.21 litres. but the miles are the same ( truck to tacho ) .
We have not seen any evidence of fuel thieft from our driver, however we cant see how there is such a difference.
How reliable is the truck telemetrics ?
How often does driver fuel thieft happen ?
Could it be a fuel leak between the tank and engine ?
Any ideas would be great, as I don’t want to start accusing the driver unless I have any evidence , I will be looking into what fuel his car uses this week,
Many Thanks
Did the truck start off with full or empty tank(s)? That could be a sizeable chunk of the difference by filling an empty tank.
I cant comment on the accuracy of MAN telemetrics, I’ve never ran them.
Driver fuel theft is common in my experience (almost obligatory if you have red on site). But at 20 gallons a week maybe he has oil fired central heating?
Unlikely that someone hasn’t picked up a 20 gallon per week fuel leak.
When we picked up the truck, it was empty, but that was 6 weeks prior to us doing the figures, wanted the truck to settle down first, some weeks there is a difference of £327 gone to £67 gained ?! over a 9 week period we have noticed £1053 of fuel missing between the fuel receipts and the trucks telemetrics showing used.
A very good fuel flow meter will have a 0.5 - 1.0 % tolerance in the accuracy, which can quite easily account about 120 litres of your shortfall. Factor in temperature variation and you can add another 200 - 300 litres.
Does the flow measurement include the supply to the night heater? (My Mars Bar would be on no!)
Don’t trust any telemetrics, the return is often a problem.
Prefer to calculate from a full tank to a full tank.
Check every tanking, and than calculate over 10 tankings for an average.
I used a simple excel spreadsheet in the past, with automatic calculations doing the work.
Checking after with recipes and the bill of the fuel company.
You be surprised how often these fuel meters are miles out.
Also if you use the truck fuel usage calculator, reset after every tanking.
Count approx 0.7 to 1 ltr per hour for your nightheater.
And 7 ltr per hour for idling.
Usage of PTO can be 10 - 35 ltr per hour, depending on what you drive with your PTO.
I have compared my MAN’s mpg readings with what our automatic yard fuel pump reads (displays MPG from the last fill up), both are almost identical figures.
Before you start going down the road of thinking your driver is on the fiddle why not enlist his ‘help’ to see how this lorry is doing on fuel, by together with him zeroing the readout on the standard OBC, then running it for a week or month and together with him checking the average fuel consumption is for that week or month, the MAN OBC is good for this, you can leave it adding up for thousands of kilometers if you wish before zeroing again.
A quick tally up then with your existing figures will soon show if further investigation is required, if for example the telematics are now proving accurate.
As mentioned any aftermarket PTO’s etc will not be accounted for on the vehicles system and will make the actual mpg figures look bad, if you have blowers you could be looking at 10 or more hours of 800/1000rpm PTO fuel usage that appears to be lost.
Juddian:
I have compared my MAN’s mpg readings with what our automatic yard fuel pump reads (displays MPG from the last fill up), both are almost identical figures.
Before you start going down the road of thinking your driver is on the fiddle why not enlist his ‘help’ to see how this lorry is doing on fuel, by together with him zeroing the readout on the standard OBC, then running it for a week or month and together with him checking the average fuel consumption is for that week or month, the MAN OBC is good for this, you can leave it adding up for thousands of kilometers if you wish before zeroing again.
A quick tally up then with your existing figures will soon show if further investigation is required, if for example the telematics are now proving accurate.
As mentioned any aftermarket PTO’s etc will not be accounted for on the vehicles system and will make the actual mpg figures look bad, if you have blowers you could be looking at 10 or more hours of 800/1000rpm PTO fuel usage that appears to be lost.
Hi Juddian
We have not PTO’s or blowers etc, its a standard truck, what do you mean OBC ? are you referring to the trucks onboard display on the dash ■■ my driver has commented a couple of times the MPG from this display, so I feel he is aware how important fuel usage is.
On MAN’s fuel figures not always on display, i usually leave the driving times as my default dash display, but is easy to find the fuel page on the menu.
Driver behaviour has the single biggest effect on fuel consumption. Firms who monitor it can initially see differences of 25% between best and worst drivers on similar work.