Fuel Economy Mystery
#1
Fuel Economy Mystery
Hey everyone!
I recently purchased my first cummins and couldn't be happier with one exception - the fuel economy.
I realize that a truck is a truck, and hoping for 'good' fuel mileage is pissing into the wind, but something seems up.
I have a 1998.5 5.9 24v. 220,000 kms. Auto (Fresh rebuild)
Levelling kit
33x12.5 BFG M/T's
3" Straight pipe exhaust
I recently replaced the fuel filter, oil, air filter, and ran some diesel treatment through the engine.
I'm averaging about 6 km / 1 L, and if I'm lucky 700 km to a tank.
I have 4 close buddies all with the same generation motors who are running 35" tires and they all average between 800 and 1000 kms a tank.
I know my speedo is out by about 17% (100km/h is actually 117 km/h) and have factored this into my calculations.
I run Howe's Meaner Power Cleaner with each tank and never run it passed 1/4 tank, so I'm not sucking sludge into the filter.
I drive it like a little old man, so driving style shouldn't be the issue.
It drives great, doesn't seem to be lacking any power and has no apparent issues, but I know this vehicle is capable of more.
Currently I'm thinking injectors or injector pump, but I'm still new to this so I was hoping you guys might have some idea's or directions to look in.
Thanks everybody!
- Drew
I recently purchased my first cummins and couldn't be happier with one exception - the fuel economy.
I realize that a truck is a truck, and hoping for 'good' fuel mileage is pissing into the wind, but something seems up.
I have a 1998.5 5.9 24v. 220,000 kms. Auto (Fresh rebuild)
Levelling kit
33x12.5 BFG M/T's
3" Straight pipe exhaust
I recently replaced the fuel filter, oil, air filter, and ran some diesel treatment through the engine.
I'm averaging about 6 km / 1 L, and if I'm lucky 700 km to a tank.
I have 4 close buddies all with the same generation motors who are running 35" tires and they all average between 800 and 1000 kms a tank.
I know my speedo is out by about 17% (100km/h is actually 117 km/h) and have factored this into my calculations.
I run Howe's Meaner Power Cleaner with each tank and never run it passed 1/4 tank, so I'm not sucking sludge into the filter.
I drive it like a little old man, so driving style shouldn't be the issue.
It drives great, doesn't seem to be lacking any power and has no apparent issues, but I know this vehicle is capable of more.
Currently I'm thinking injectors or injector pump, but I'm still new to this so I was hoping you guys might have some idea's or directions to look in.
Thanks everybody!
- Drew
#2
what lift pump is on your truck? Do you have any gauges? You could have low fuel pressure thus killing the injection pump would lead to poor fuel mileage. I am not familiar with the fuel additive your using so you can always try not using it for a tank or 2 and see what happens. Also found that for best mileage in these change the differentials over to synthetic gear oil helps.
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