Can a tune up greatly improve gas mileage? I did it out in my 94 f150 5.0L and its like 6-9 MPG...not right
Pulled a wire from the dist and it was rusty. if i do a tune up could it improve mileage to where its supposed to be 14-20? or is there something more wrong

 

if its not skipping or running really rich like then no, a tuneup will not give 5+ more miles per gallon.

 

Well the gas is going somewhere, it must be running rich, ive gone 75 miles on a tank that had 17 gallons (i know cause it was new tank) and its down to almost 1/4

Not right for a 94 f150 5.0 correct?

 

thats really low. but heres one thing, are you positive the sending unit is working correctly? it being a new tank and all.

 

Ill fill it tomorrow and see how much it takes.

 

How many miles has it been since the last tune up and what was done?

 

Dont know, just bought the truck...it has 196k on it. Lmao probably hasnt had a tune up in forever seeing as the wire i pulled was rusty.

 

If you're not certain when the last tune up was and the wires are rusty, it probably wouldn't be a bad idea to check things out further. I did a thorough tune up on my 95 F150 a couple of years ago. Here are a few things to look for:

spark plugs = center electrode should be square and flat not rounded over, check for proper gap

dist cap = check for corossion on terminals on underside of cap and tip of rotor as well

spark plug wires = bend and check for cracks use ohm meter and check for higher than normal resistance

PCV valve = remove and shake, should rattle freely, if not get a new one or spray some carb cleaner inside and shake to clean

air filter, fuel filter, crankcase filter = I replace mine every year

oxygen sensor = usually gets gummed and throws off signal to the computer, should be replaced every 50,000 miles or so

throttle body and IAC valve (idle air control) = carbon builds up behind throttle plates (I removed mine and cleaned with carb cleaner and tooth brush) some manufactruers have a warning about using carb cleaner on throttle bodies though

listen to the injectors = I use a stethescope I got from the local parts store with a long probe at the end. The injectors should make a sharp crisp ticking noise if it's adull thud, run some fuel injector cleaner through the gas tank or have the injectors professionally cleaned

jack the truck up and rotate the wheels by hand = make sure the brakes aren't sticking or draging. make sure the tires are inflated properly.

That's all that I can think of at the moment that would effect gas mileage.

 

Well i filled the tank, took 10 gallons which is about right. Tranny is screwy on that think its getting worse. Think it may be slipping....it feels like it randomly goes into neutral on me. Seems to do it more when hot. It has enough fluid....any suggestions on either problem?

 

If the tranny is original to the truck, it probably wouldn't hurt to make flushing the tranny part of your tune up list. What color was the fluid when you checked it?

On the slipping issue, it could be the torque converter, or it could just be that the tranny is ready to die. 196k is a lot of miles.

 

I just did a tranny flush due to a bad leak not too long ago, hope i dont need a tranny

 

Also, if it was ready to die wouldnt it do it all the time? It doesnt happen all the time, seems to be when warm it happens more.

 

Does the truck have a thermostat? When I bought mine I found that the previous owner removed it. When I was driving it without the t-stat it just sucked down the gas. OBD1 computers are very sensitive to engine temp and will make the truck run pig rich without a t-stat.

Also, seems like a dumb question, but I figured I should ask. Are there any fuel leaks? Check the filler hose(s), all the pressurized fuel line connections, and take a good look at the lower intake manifold to see if your injectors are leaking (from bad o-rings).

 

New rear tank, front tank doesnt leak. has a T stat just did a water pump and changed it while i was at it.

 

I've heard people swear by Lucas for the tranny. Never used it myself so I can't comment on how well it works or not. Good luck.