Still poor gas mileage, 01 185k miles
 

This is my wifes drive to work and back vehicle. We bought it new and forever have tracked gas mileage. Well lately we had a string of problems. IMG leaking causing lifter to stick and enging to sludge up a little. Fixed that. Then Fuel pump failed. Replaced. Started getting hard to start after fuel pump replacment so i checked fuel pressure and it was a little low, 58 psi at startup and 55 running. Removed upper plentum and found clean spots, so i replaced with new MFI spider , and new gaskets. Now it starts like a champ and appears to run perfect. the mileage we are averaging is still about 1.5 to 2 mpg worse than normal.

New
Wires, carquest premium
plugs, OEM delco plat
Dist Cap, Accel performance, 44 dollars
spider assy
fuel pump
fuel filter
cleaned Mass Air Flow Sensor

Could this be an indication that EGR is plugging , or would you see a code. I have looked around for vacuum leaks and cannot detect any. To try to get some mileage back, i have been running higher tire pressure, 5w20 oil, synthetic gear/xfer case/ tranny fluid. I dont know what else to do too try to get my mileage back.

With all that taken care of my first thought would be the ignition coil. It may spark but might not spark well enough. I think a replacement can go for a couple of 20 dollar bills.

The EGR can become cruddy. I would take it off and clean it with sensor safe carb cleaner and a wire brush.

Also, you might want to look into replacing vacuum lines at that mileage. Just to rule it out. Most of my peers replace them at the 100,000 mile marker and some shops offer that service as an add-on to the tune up package.

Have you checked you pcv valve?

What mileage are you getting in town? Lots of stop lights in my town and I average terrible mileage (13-15). If I get on the freeway though, its 22 mpg all the way.

Hope this helps.

Thanks, i have not cleaned the egr and will definately do that. Also i have not replaced the vacuum lines so maybe ill be doing that as well. i do plan on keeping it for a good while yet. I have checked the pcv valve and it looked okay, clicked when i shook it and is restrictive when i blow in it, but lets air flow easily when i suck on it. In town, i get about 16, when it is running correctly. Around where i live, there isnt a lot of town only driving. Im not saying mileage is horrible or anything, it just isnt where it should be for where we are. Unless its just the poor quality of fuel or something.

i should add also, my wife just went to PA and during a piece of that trip, we always get 22 to 23 mpg, last weekend, she was only at 20.6mpg.

just wanted to update, that mfi spider seemed to eliminate all the hard starting issues we were having. If i could get my fuel mileage up a little, i would be back in business.

It's possible that the gas stations have switched to their "winter mix". IIRC, it causes a drop in mileage. Do you start the truck in the mornings to let it warm up during cold weather? That'll also do it.

Well my wife has been home now a little over a week and just got gas today. 15.9 mpg. This truck is really getting on my nerves. Could there really be a 2 mpg difference between longer trips and her short 6 mile commute to work now. She used to drive about 20 miles to work and we always used to avg 17.5 to 18 mpg.