WORSENING FUEL ECONOMY

[akrockhound]

My fuel economy seems to have dropped from say 15 mpg average to about 10.

The change seemed pretty abrubt in the last tank of fuel.

I have about 7k on current fuel filter, airfilter is original with 12k on it but showing almost new condition at indicator under the hood.

I am burning #2 and the weather is getting warmer. Fuel economy should be getting better this time of year.

Truck seems to run fine and I'm not making any black or white smoke.

Should I change the fuel filter as a first step????

Any other ideas? Bring it to the dealer if it doesn't get better after changing fuel filter?

Does the instantaneous fuel economy display in the driver's information center actually take into account engine condition/fuel type/temperature etc or is it a more generic 'ball park' measure of fuel economy?

[ 04-09-2004, 11:56 AM: Message edited by: akrockhound ]

[More Power]

Unless you've noticed a difference in how the engine runs or performs, I doubt your fuel filter needs changed unless you've picked up some bad fuel recently. However, it can't hurt as a first step in troubleshooting for just about any engine running problem.

I wouldn't put a lot of faith in the fuel economy calculations you're seeing on the message center. Run two or more tanks of fuel, being careful with recording miles driven and gallons consumed, then calculate your fuel economy with a calculator. Just my opinion, but a Duramax delivering just 10 mpg when driven empty should exhibit other engine running and power problems.

A couple of years ago we were traveling the Interstate in Wyoming with our travel-trailer in tow, and passing Dodges along the way. That 150-mile leg of our 4500 mile trip produced 9.7-mpg. Running at extra-legal speeds with a TT will do that. I can't fathom an empty truck delivering just 10 when driven at any sane speed.

MP

[64postcarnut]

We got a DIC indicated 15.0 mpg on a trip from Denver to Vegas.Speeds were 80-85 mph most of the way.We were also pulling an empty 18' open car hauler.Even had to put the a/c on near St.George.

I get 20-21 in empty,all highway driving staying at 65 mph.

[Cliffee]

I had my milage drop from normal to around 12 when my dealer didn't tighten the hose clamp at the airbox. The truck ran great but the milage suffered. I would imagine any small intake leak could also kill milage.