Thread: Declining fuel economy from 300tdi

Originally Posted by JamesH

Hi

Ive noticed the last half dozen tanks of fuel have yielded disappointing economy. Ive done a quite a few country trips and if anything I was expecting an improvement. I'd say nearer to 11.5l/100 than my usual 10.5. It's being experienced over both tanks and Ive have a look underneath, no sign of weeping leaks.

It has 223K km on the clock and the injectors haven't been done.

If power has reduced it's done so so slowly I haven't really noticed.

Smoke, some under power but nothing too worrying.

Can't rule out fuel quality as I buy a lesser known cheap brand (Liberty). Ive been using the same supplier for a long period.

Any thoughts?

If there are not restrictions in the air inteke and the fuel filter and lines are clean I would test the injectors and calibrate if needed.
Also have a look each outlet port in the injection pump if they are clean. Some times they give problems with blockage if the fuel filtration it is not good.

Originally Posted by JamesH

Hi

Ive noticed the last half dozen tanks of fuel have yielded disappointing economy. Ive done a quite a few country trips and if anything I was expecting an improvement. I'd say nearer to 11.5l/100 than my usual 10.5. It's being experienced over both tanks and Ive have a look underneath, no sign of weeping leaks.

It has 223K km on the clock and the injectors haven't been done.

If power has reduced it's done so so slowly I haven't really noticed.

Smoke, some under power but nothing too worrying.

Can't rule out fuel quality as I buy a lesser known cheap brand (Liberty). Ive been using the same supplier for a long period.

Any thoughts?

cupple of things to say, first 11 is not bad, im fitted out with both front and rear bars, and some other nick nacks, also i have a power chip. im advraging around 14l/100 with mud tyres (31") second thing is that if your out in the country alot of dust roads can fill the air filter quickly, im not sure if you know or not but diesel engines have to air throttle so they constantly have air pumped through reguardless of throttle position, hense the filter plugs faster than a petrol engine would. a k&N filter is a good option because they preform better and can be washed hence are cheeper than the 30$ ryco deal you get at s cheep auto.

as for diesel im going to duck down as to not get hit by any one throwing tomatos, but there is no such thing as cheeper fuel. if its crap it will be cheep , if its cheep it will be crap, if its imported from singapore you will be probably burning more of it hence no saving. i dont want to sound too self righouse but i always buy from shell, i know they refine it in australia and they contole the grade to australian standerds. just look at it as it comes out of the bowser, its clear and crisp. it has to be better. for a few extra cents per L you will probably get more out of your fuel filter wich is about 60 bucks. so if your filling your tank with mud and filtering it for 60 bucks and burning more fuel its not woth it for me. ok im going to get off the soap box.

last check tyre pressures and mud in rims, its easy miss tyre pressures on a 4wd as they almost look the same low. i prefer 40 psi around town in my mud tyres altho they can reach 65 i find they are best at 40.

let us know how you go.

also as for fuel, altho you may have used the same supplyer, they may have tryed a diffrent batch, or may have used a diffrent supplyer.

if i couldent get shell fuel i would go moble, for the reasion they are the second and only other fuel company that refines in australia that i am aware of. both of wich are in melbourne.

It's coming up due for a minor service but I'll take a look at the air filter. Not sure I'd know a slightly manky filter if I saw one.

I'm on top of the tyre pressure. I'm using good ole fashioned 7.516s

I hear what you're saying about fuel but Ive been suckered in because this place is local and I get an extra 4c off from shopping at my IGA which I'd do anyway. But it's food for thought.

When were your valve clearances last checked?

Originally Posted by Jock The Rock

When were your valve clearances last checked?

Ummm, about twelve months, maybe 18.

Originally Posted by JamesH

Ummm, about twelve months, maybe 18.

Roughly howmany ks ago was that?

Originally Posted by JamesH

It's coming up due for a minor service but I'll take a look at the air filter. Not sure I'd know a slightly manky filter if I saw one.

I'm on top of the tyre pressure. I'm using good ole fashioned 7.516s

I hear what you're saying about fuel but Ive been suckered in because this place is local and I get an extra 4c off from shopping at my IGA which I'd do anyway. But it's food for thought.

no worries mate, we all have to do what we have to do. best rule of thumb with filters is hold it up to a light if you can see clear light braking through it she is good, if you cant, how the hell can air get through it ? lol when you buy a new filter hold it up to a light and you will see the diffrence, in a pinch wack the filter (with care) against somthing like a board durty side down. you will be surprized how much comes out. and it will get you buy untill you can get a new one.

dont try to wash a paper filter as it will turn to mud and further seal the dust togeather like cement ! ( sounds like the voice of experence)

Gidday James
Sip on a Pimms mate
I agree with Jock,get the valve clearances done if you havent in the last 50000ks.They effect the time the valve is open for the engine to get its fair suck of oxygen.Our Trytoo went so much better every time I adjusted them.Its relatively easy IF you are mechanically minded,if not get a GOOD mechanic to do it.
Next check,are you getting full throttle??? The TDi can suffer from a stretched cable.EASY CHECK.
AT FULL OPERATING TEMP get an assistant to hold the power pedal FLAT TO THE FLOOR.Dont wory it cannot EXPLODE,its governed.NOW,see if you can manipulate the mechanical lever on the fuel pump to see if it can move further than the cable is pulling.If it does respond,a new cable is well worth installing,keep the old one for your travel spares kit!!!
GOODLUCK!!!
Andrew