Poor MPG 1989 2.9l

[ptofimpact]

1989 Ranger 2.9L So far, replaced Plugs, Wires, Dist Cap, Rotor Button, Fuel Filter, Fuel Pump[in tank] Engine Coolant Sensor, Battery.
Cleaned Throttle Body, starts good runs smooth but worse MPG then before.
Any ideas appreciated.

 

[powerplantranger]

How bad is bad? The fuel now a days isn't helping, that's for sure.

 

[jhammel85]

If you did all of that, check timing too. That can really kill MPG.

What is the difference between the old parts and the new ones? In other words, how much did you lose?

 

[RyanL]

Sounds like you have most of the bases covered. Also check out the intake air temp sensor, fuel pressure regulator (might be dumping fuel into the intake out of the vacuum port in the rear), and tire pressure (keeping it fairly high helps a lot, but don't exceed the maximum PSI). Bad compression and clogged injectors can hurt fuel economy also. What is the actual MPG that you're getting. If it's down in the teens on the highway then there is something wrong.

 

[ptofimpact]

Thanks for all the replies, was getting 17-18 local, filled up yesterday, 7.0 gals, and 78 miles on odometer since last fillup, all local 10-11 mpg. Tires inflated fine, oh an altho its a 1989, I have 64,000 Original miles on it, always been maintained good, change Oil and filter every 3000 miles.
Timing hasnt been touched this time yet.

 

[jhammel85]

hmmm...

Any drivability problems at all? This might sound dumb but try to lift up one wheel at a time and make sure none of them are dragging. Something like a seized caliper can really kill the MPG of your truck.

How about another gas station? Is there anything that could of happend between the last "good" fill up and the "bad" fill up where you found the MPG drop?

 

[Mike828]

What about o2 sensor?

 

[jhammel85]

^ good point too. Any bogging down?

 

[ptofimpact]

Thanks again all, same gas station, in same town. It rolls real smooth along the road, highway, doesn't feel like dragging in any wheels, but will check that. O2 sensor....cant say I even know if I have on, or if so where the heck it is?
It used to Bog down before all the parts were replaced, no more now.
Also, I put Injector cleaner in the fuel 2-3 times a year.

 

[Earl43P]

O2 sensors are to be replaced at 60k miles.

They affect fuel mixture greatly, so it's a good place to start.

You'll find it on the Y pipe.

 

[RustedRanger]

Like they said,check the timing. When I did mine I got a bad rotor (cheap) and it would move back and forth on the shaft. There is a gas station near my dads house where I was getting gas when I would go mow his yard....I noticed once that on the way home it ran real crappy and sucked gas and I thought something had went wrong with the truck. Later on I noticed this again after getting gas there,so now I go elsewhere

 

[RyanL]

I just re-read your original post and noticed that you cleaned your throttle body. Maybe that messed up the intake air sensor located in the middle intake riser tube. The intake air sensor controls the A/F ratio just like the coolant temperature sensor - if the computer sees the air coming in as real hot, it will dump a bunch of gas into the motor to help prevent spark knock. Same thing if it sees it as being real cold, it will make it run rich to keep it running. I don't know how sensitive those things are to cleaners (some cleaners might damage them), but it's very easy to check out. Do you have a voltage meter?

 

[ptofimpact]

RyanL, thanks for the reply. I used a spray cleaner specifically for that purpose, CRC Throttle Body & Air Intake cleaner. Sprayed some in and wiped gently with cotton cloth.
Voltmeter, have a Radioshack, not a Shop quality pretty sure.

 

[4.0B2]

there's certain places i get better gas at than other stations..
but that mpg sucks man... my 2.9 got 19ish in town w/ way more miles than that...

what's your gearing and tire size?

 

[Big Jim M]

HA!

there's certain places i get better gas at than other stations..
but that mpg sucks man... my 2.9 got 19ish in town w/ way more miles than that...

what's your gearing and tire size?

That goes against everything that chemistry teaches us.. It is highly doubtful that one 87 octane would give better mileage than another 87 octane..
If true you'd have a wonderful case against one or the other stations.. perhaps even both!!
Big Jim

Ps... Also if true the station with the best milage would be sold out of gas before the other one would sell a single drop..