Drop in milage, where to look?
 

OK, when I bought my truck last summer it was getting 24+MPG on the two lane roads running 65 and around 19-21 on the interstate. Now it is only getting around 17 at either speed. I changed the fuel filter and it didn't help, air filter is pretty new too.

My timing tools won't be in until next week and I'll be out of town so I cannot check the timing until I return from my trip.

What other stuff should I check out before I leave on my trip? I'd really like to get my milage back up to what I was getting to save some fuel as I'll be driving it about 2000 miles or more next week.


Ideas? I've been playing with it turned up some, could the soot have plugged the cataletic converter? I may straight pipe the CAT this week, been meaning to but just been waiting to put a full exhaust on it and just havn't had the money yet.

Thanks for any ideas or suggestions to get my milage back up.

George




Oh, one more thing, I've gotten as high as 24.6mpg with winter blend ULSD so I'm pretty sure it's not the fuel. :)

Your cat could be a problem but more likely its your fuel, if the kitty was plugging performance would be down also.
I notice a big difference in suppliers.
I have also had a bad fuel filter (non Fleetgaurd) that cost me mileage, I changed it out and all was OK?

I don't know if the '97s had a cat, but my '96 came with one. Try the simple things first like cleaning the pre-filter, and also reset the valves. You are also seeing a slight drop due to the refining process for ULSD. You can try adding a good quality fuel treatment or even a quart of two cycle oil with each tank full.
Tom

:D
I really don't think it is the fuel as the same fuel (ULSD w/ winter blend)from the same store has gotten me over 7mpg better than what I get now.

I'm not sure about the performance as I've changed so much lately it is hard to tell for sure what is happening.


Also, it does have a Cat, and I run 16oz of power service and 8oz of 2 stroke with every tank. Nothing has changed except my milage. I cleaned the prefilter screen when I changed the filter.

One more thing, while the valves may need to be checked, the last time I got over 24mpg was only 1,000 miles ago so I'm not sure if they would go out of spec so quick?

Anyway, don't think I'm not listening to advice as I am, just relaying extra info I may have left out earlier :)

Thanks,
George

try changing the filter first off

Ok George, is your transmission slipping more? Parking brake dragging some? When the cats plug, the EGTs will go through the roof and you won't be able to build boost like you used to. Speaking of boost, you don't have a boot leaking, do you?

I just changed the fuel filter and it didn't help any (if that's the filter you mean) Went with a NAPA filter and it looked the same as the one I took out, only cleaner ;)

George

check your brakes make sure they're not hangin up on ya.

I had a RF caliper hangin on me, that alone cost me about 4 MPG (also gutted AFC at the same time, shouldn't have helped)

Curtis

did you need to replace the caliper to fix the problem?

How old are your injectors? Sounds like a bad injector maybe...does it idle smooth or a little rough?