1985 Ranger Gearing vs Bad MPGs

bbbc3 · Sep 3, 2014

Ok, I'm sure this forum has been beat to death with this question but I didn't see what I was looking for when searching.

I have an 85 4x4 ranger with a 4sp, 3.73 gears and 7.5 rear eand. I get crappy gas mileage! 9 mpg! I just had the engine rebuilt and it runs really nicely but I just can't figure out the bad mpg? Could the gearing be the cause?

Oh and I have 30" tires on 15" rims.

Your thoughts?

James86 · Sep 4, 2014

What motor?

bbbc3 · Sep 4, 2014

James86 said:
What motor?

2.8

Rowdy Fitzgerald · Sep 4, 2014

I'm thinkin it's your carburetor. You should get almost double that. I can't remember if the 2.8's had a O2 sensor, maybe that needs to be replaced also. But tune up that carb and see if that helps.

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drsvox · Sep 4, 2014

I second the motion that it's the carburetor. And yes, 2.8 has one O2, driver's side exhaust manifold...very easy to get to.

bbbc3 · Sep 4, 2014

drsvox said:
I second the motion that it's the carburetor. And yes, 2.8 has one O2, driver's side exhaust manifold...very easy to get to.

Funny you mention that. As I was under the truck I noticed that the O2 Sensor was removed from the Cat and the hole plugged up.. How hard/expensive is it to replace this sensor?

drsvox · Sep 4, 2014

An O2 sensor shouldn't cost you more than about $25 most...but you mentioned the cat. You shouldn't have an O2 downstream...only upstream and it bolts into exhaust manifold.

I suspect your cat had threads for a sensor, but was plugged as it's not needed.

swynx · Sep 9, 2014

bbbc3 said:
Funny you mention that. As I was under the truck I noticed that the O2 Sensor was removed from the Cat and the hole plugged up.. How hard/expensive is it to replace this sensor?

02 sensors are easy to replace, some rigs run without them but it really does help to have a new healthy one put in there. if the hole is plugged i would iether go to the junkyard and get a new exhaust manifold, or the parts stores sell an adapter piece so you can install an 02 sensor, i think there like 15$ on summit.

i think 1995 was the first year of the down stream o2 sensor? i know my 1994 4.0 only has 2 upstream (before the cat)

also, my buddy had a 2.9 on 31's, the thing was stupid slow and would barely do 70. what is your current gearing?

alwaysFlOoReD · Sep 9, 2014

When figuring mileage, have you compensated for the different non-stock tire size?
....I just ran some numbers, it seems it's only about 10% different, not enough to make the mileage that bad.
Richard

martin · Sep 12, 2014

The 4 speed is not helping things. The 2.8 will run quite nicely without the computer plugged in but fuel consumption goes down the toilet. to see if the computer is working, connect a timing light and see if the timing advances as you raise the rpm. Don't start throwing parts at it, diagnose the problem first.

1985 Ranger Gearing vs Bad MPGs

bbbc3

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