1988 2.9 fuel consumption

[ferlar]

Hello friends. My little Ranger is running well but I'm only making 13 miles a gallon! Is this normal? If not, could anyone give me some suggestions as what I can do?
Thank you so much.

 

[RonD]

There is a Fuel Pressure Regulator(FPR) on the engines Fuel rail, looks like a small "can" and will have a Vacuum line attached
Check that vacuum line for gasoline, if found replace FPR

You could be running with lower compression or poor spark timing
Use a Vacuum gauge to test engine vacuum at idle, 17-21" is expected
Lower can mean poor compression or poor spark timing, re-time spark first

 

[Shran]

13mpg is quite low, when I had a 2.9/auto truck I would average around 17-19. Manual trans trucks are capable of much more, 20+, I got over 25 on a couple occasions.

As Ron said check your FPR, the usual symptom there is hard starts when warm. Coolant temp sensors are somewhat known for failure on these trucks too and often cause poor gas mileage issues too.

Lots of other things could be at fault as well - dragging brakes, plugged up catalytic converter, driving habits, etc.

 

[ferlar]

Thank you guys so much! I will check the FPR and report back. I drive slow, brakes are free and this truck does not have a catalytic converter so I will keep looking at the things you suggest.

 

[19Walt93]

Unplug the spout connector and check the base timing, I think the spec is 10 degrees but you should be able to get away with 12 or so. When you plug the spout back in the spark should advance, changing the sound of the engine. Is the temperature in the normal range? If it's running cold it will use more gas. I know you're in Texas- by cold I don't mean 10 degrees, I mean below about 190. How much stop and go/ city driving do you do? It gets zero mpg sitting at a stop light and accelerating from a stop uses more gas than cruising. I assume your gas is diluted/polluted with alcohol like ours, more alcohol equals fewer mpg. Also, your truck is a 4x2, a 2x4 is lumber.

 

[ferlar]

Thank you for your answer and helpful comments. I live in Tyler, this is a small city with easy traffic and I treat this old lady with a very soft foot. I have another symptom that I wonder if it is related to high fuel consumption. There must be a problem in the fuel tank vent system because I have to fill up very slowly. Would that have anything to do with it?

 

[RonD]

No, that wouldn't effect MPG

The filler hose would be the issue
1988 should have this type of filler hose: https://m.media-amazon.com/images/I/61FcG6ngdoL._AC_SX679_.jpg

If you fill a coke/beer bottle with water and flip it upside down to drain the water out it comes out very slow because it has to let air in to let the water out, they have to share the small opening in the bottle
If you do the same with a glass of water, the water comes out fast because air can come in fast

The filler has a separate IN(gasoline) and OUT(air) hose

In the above pictured filler the gas goes in the smaller hose, and the air comes out the larger hose
The Air comes out the smaller holes in the metal part of filler
So if gas can't go in fast then either the smaller tube is kinked or blocked, or the air can't get out, so both have to share the smaller hose

There is another Vent on the gas tank, the EVAP system
In the engine bay is a charcoal canister usually mounted on rad support drivers side
This has a hose that runs back to the top of the gas tank
As gasoline flows in the air from the tank flows out and thru the charcoal filter in the canister, limiting gasoline fumes(pollution)
If that hose/filter gets clogged up it can limit how fast gasoline can be pumped in
Pull the hose off and blow thru it

 

[rang-a-stang]

Ha! I literally JUST went through this! Fixed it yesterday.
thread where I fought a slow fill