My '94 Dakota runs great when I first fill it up. I'm getting 18-20 mpg on the highway. After about 1/2 of the tank is gone, the truck start stumbling and running rough. Almost like it's running out of gas. It wont go over about 60 mph at that point. Then I fill it up and it runs great again.

It has the 318 and 140,000 miles.

Any ideas?

Thanks, Craig

 

try fuel filter those are in the tank on the bottom of the pump. check fuel pressure to be sure its the pump or filter....you don't want to replace the pump if you don't have to...200 sum bucks.

 

Depending on where you get your gas, there could be sediment in your tank, so when the tank is full, there is more gas to have the sediment in, and when you get lower on gas, it is more concentrated. had this prob with a tercel i once had. drop the tank and drain it and look in the bottom.

 

my brother had a similar problem with his ford. turnrd out that when he was putting in an additive, the little foil seal on the bottle must have fallen in. every so often the truck would konk out and after a few minutes or more it would start. it kept happening and we couldnt figure it out. finally took everything apart and cleaned the tank out like was already mentioned and found the foil piece. you could see the imprint on it from the gas intake in the tank. every so often it clogged the gas line and then released itself later while we worked on the truck to get it started

 

I'm going to drop the tank this weekend and check for sediment and other debris. Can the fuel filter be changed by itself or is it integral with the pressure regulator?

Thanks, Craig

 

i'm pretty sure dad and i just replaced the filter its self but its been awhile ago.

 

As I understand it, at some point, they changed it to an in-tank unserviceable filter. Since the 1990 service manual I have shows steps on how to change out the fuel filter, my best guess would be that in 1992 when they changed to the Magnum engines, they also changed to unserviceable filters.
Also, there are two fuel filters. The first one, for what I believe started in 1992, is located on the bottom of the pump unit. The second is located inside the fuel pressure regulator.
I'm sure if one is handy enough, they can probably find a way to clean/renew/etc the filter on the bottom of the pump unit.