MPG on '96 HELP!

[Fish On]

I have a '96 with 126,000 miles on it. This truck used to get a steady 18. 5 to 19. 5 mpg on the highway. (my commute to work is approx 85 miles round trip) Now I am lucky to see high 16's to low 17's. Any advice on what is going on. Only modifications are tst 230/605 and a set of gauges. Thanks in advance!

 

[illflem]

Winter fuel?

 

[BCFAST]

A few things

As illflem suggested, winter fuel might be part of it. At the age of your truck, you could be dealing with air leaks in the banjo fittings, the fuel filter or lines. When's the last time you changed your fuel filter? How about your intake setup? Is your cat plugged up? How about the performance of the truck>? Is it getting sluggish? Give us a few more hints!

 

[Fish On]

fuel filter changed about 8000 miles ago. Intake is stock haven't checked hose fittings for leaks but I will next. Cat could be clogged exhaust is stock. Yes performance is sluggish compared to when the tst plate was first installed. Thanks again!

 

[gitchesum]

I would definately go over all the boost clamps. Those little boogers have a way of working themselves loose. I might also look at getting rid of the cat. It might not help, but it sure won't hurt it.

 

[FL70CAT]

Overflow Valve might need replaced

 

[BCFAST]

When looking at the fittings, you wont SEE any leaks! What I suggest you do is, go to a Bosch shop and buy 4 'sealing washers'. These are metal washers with a rubberized coating. They fit on the inside and outside of the banjo bolts on the mail fuel-in on the pump, and the overflow valve on the top-side of the pump. They arent leaking fuel out, they're leaking air IN!!!! This was a big source of free power found on my truck. If you havent cleanted your prefilter screen, do it! The other place to look is the rubber fuel hose against the firewall. Again, leaking air in, not fuel out.

 

[rwilliams4]

Better 12V mpg

I haven't tried this yet, but it is something to think about. Try replacing (or at least, checking the Intake Air Sensor) If you go to http://www.smokindiesel.com/Technical.htm it should give you a lot of information on the IAT. According to the technical info it will improve mpg by almost 2 mpg.

 

[illflem]

rwilliams4, you're speaking of a 24 valve, the Intake Air Sensor on a 12 is only for the grid heaters.

 

[Matt42]

Maybe valve adjustment is due?

 

[Fish On]

ttt