Over the last few months I have been noticing that my fuel economy has been getting much worse than it used to be, I have gone from about 12 MPG to about 6. I have an '88 W150 with a 318 and a TB. I have replaced all of he obvious things like temp. sensors, O2 Sensor, blanked EGR, all vacuum hoses blanked. I have not seen any improvement. The computer has no codes stored. I feel like it is still running very rich because if you walk behind and get a face full of exhaust, it will sting your eyes, indicating poor combustion and unburnt fuel. The only thing I have left is my exhaust. In the summer, I took of the stock exhaust system, and ran true duel all the way back. I have 2 1/2 inch pipes coming from each manifold, each side has a free-floe CAT and muffler. I do not have any kind of H-pipe or crossover. Would the change in back-pressure in my engine have that effect on my MPG? Or could it be that there is no scavenging now that there is no link between engine banks? Any ideas would be very helpful, thanks.

 

could be winter gas. i don't know where you live but i have been reading in the 2nd gen section that a lot of people are getting worse gas milage since it is winter time and the gas has changed a bit.

 

Surprisingly enough, my gas mileage has actually INCREASED over the past month or so from 10 MPG to upwards of 13. And I am located in NE... Explain that!

 

sound like we have another mystery on our hands gang!!! ill go with the blind red head ditsy girl!!!