Ok guys, heres a question. I am having issues with fuel mileage on my 90 f150 w/302 AOD. I have completed all of the usual tune up procedures, ie. cap, rotor, plugs, wires, fuel filter, oil and filter, replaced all vacuum hoses that were cracked or broken, and ran all Haynes manual tests for fuel pressure regulator. Regulator is fine. I did find that there was a blockage in the fuel return line at the tank. The line was kinked!! Strange huh?! I was getting a reading of 75 psi at the reg. and now it is 32 at idle. I have gone from 8.5 mpg to 13.5 mpg but with only 41000 miles on a rebuilt motor the mpg should be better. I'm thinking it should be around 17 or 18 with all of the above changes and a K&N air filter installed. I have also changed the trans filter and fluid including draining the converter. I am in the process of running some Chevron Techron injector cleaner through it but have only gone through a 1/3 tank. I checked for codes before starting the repairs and received a 33 and 42. 33 says egr not fully seated or open (this was a stored code). 42 says a rich O2 condition (a KOER code). Figures with the low mpg. I cleared those codes and have not run enough miles to allow the computer to receive any new codes yet. ANY help would be greatly appreciated!

Thanks in advance

Mike

FYI this is a 4x4. Also would like to know if removing the water lines from the Throttle body would help or hurt my performance. I have cold air going into TB and the water is heating the incomming upto engine operating temp?? For performance this makes little sense to me.

 

Hey Mike, just out of curiousity, how do you check the pressure at the fuel rail and with what tool? I was told to do this today due to crummy mileage, but don't knw where to start...thanks!
Jay

 

Jay,
Depending on the year, there should be a shrader fitting kind of like a tire valve located on the fuel rail near the distributor. you can get the pressure guage kit from any auto parts store. Costs between 30 and 50 bucks. I got mine from O'Reillys auto parts. 48 bucks!

 

ok guys. there has got to be a ford mechanic out there who has some idea what I can do?!

 

Hey Mike, just out of curiousity, how do you check the pressure at the fuel rail and with what tool? I was told to do this today due to crummy mileage, but don't knw where to start...thanks!
Jay

 

Thanks, Mike, I'm off to AdvanceAuto first thing tomorrow...sorry for the double-post.
Jay

 

well, 40 views and no help yet. guess i've stumped u all! at leastI'm not alone. LOL

 

The water lines are to keep the TB from icing up and to improve performance.
I do not know how it would improve performance but that is what ford said in one of the manuals.

 

thanks subford. by the way. any ideas on my other problem?

 

I would check your timing and any play in the timing chain, I know you said it only has 41000 miles on it but I would check it anyway.

 

base timing is at 10 deg. and there is no "walking" on the timing mark. usually it will walk when the chain is worn. might be worth checking anyway. thanks

 

could it be the crap gas we get these days???? i average between 10-18 mpg depending on where i get my gas

 

Check the drive line (alignment, tire pressures, u-joints, axles, and brakes)

Any of these can create a substaintial loss in fuel mileage