We recently purchased a 1999 Dodge 1500 conversion with only 51,000 orig. miles. It is a 5.2 L. Only getting 10 miles to the gallon combined hwy. city. Tried a complete new tune up with no change. Runs great. Just added injector cleaner...next going to have throttle body cleaned. ??? I talked to a man that had the same van on my fishing trip and he was getting 17 mpg. with a 2002 Canadian camper version 5.2 L.
ANY OTHER SUGGESTIONS...I AM DESPERATE TO IMPROVE THE GAS MILEAGE.

 

Check for computer codes.

Check for vacuum line leaks
02 sensor
coolant temp sensor.

 

He is not correct. Maybe...maybe he might come close to that if he babied it and only drove on the highway. Combination highway/city, no long idling, and without much cargo should yield around 13 MPG.

 

There is no way on God's Green Earth a V8 van can get 17 MPG. Even when my 93 B150 was new I couldn't ever get more than 15 MPG with no cargo on the highway with a 3.9L and 5-speed manual.

If your V8 automatic is in top form you'll maybe get 13 MPG, all highway with no load.

 

Which transmission does yours have? I get on average 12.5 combined with the 5.2L, 36RH non overdrive and non lock up converter transmission, and 3.21 ratio rear axle with gross loading of 5,600 pounds. I have pulled about 13.5 to 14 on the highway and as low as 8.9 in city driving.

 

I hate to bring this back form the dead. But I recently bought a 1999 ram van 1500 with the 3.9 v6 and automatic. I did a tune up, full synthetic oil in the motor and rear-end, New plug wire air cleaner rotor cap. After 300 miles of mixed in town/highway after 304 miles (it has a 32 gallon tank!) I got 18.345 mpgs. (91 octane shell nitro) Not bad! At that rate I can go 600 miles to empty. Not bad range. The trans needs rebuilt but it's a 3 speed so I hear it's easy. Really loving this van.

 

I am about the same with my 6000lbs 02 3.9.

 

I get 17 mpg without a problem on highway and 13 city with my 96 5.2. I also run synthetic 50/50 blend oil along with non-ethanol 93 octane gas... She purrs like a kitten!