2.8L TERRIBLE mpg

[FordFanatic]

Hi everyone, I recently bought a 1985 Ranger 4x4 with a 2.8L/FM145 and 3.73 gears. The truck was previously an Oregon department of Forestry truck. It only has 40k on it.

I've been driving it around and I think it's getting about 10mpg. Now I know the 2.8L isn't known to be the most fuel efficient engine (I searched LONG and HARD for a 2.3L 4x4 and couldn't find one so I settled for this). Now I have done an oil change and I'm running Shell Rotella 10W-30 with a fresh FL-1A. I haven't changed the plugs, wires, cap, or rotor yet. The engine is all pretty much stock, still have the smog pump on it as well as the TFI ignition. It also has working R-134 A/C (I'd like to keep that). I'd like to Duraspark swap it soon. (Even though you wouldn't think the TFI was that bad with only 40k). Are there any other modifications I could do to improve the mpg on this truck? The reason I bought it was to get better mpg than my '78 F-150 4x4 and so far it's not. Any help will be appreciated.

Thanks!
- Steven

 

[Scrambler82]

Wow, nice truck.

I am not sure, not being a mechanic, but there were fuel system issues when the Ranger first came out and the 2.8, well that engine was the worst thing to happen to a Ranger.

You probably want to keep it stock but consider getting a 4.0L Push Rod Motor for it.
No one will tell the difference between the 2.8 and the 4.0 motors, except you and it is a bolt in (I think) !

If you are getting bad gas milage you might as well have a 100 more HP and more torque too so putting in a 4.0 will result in better power for the little truck.

 

[FordFanatic]

I've been checking the mpg off the gauge so it can't be very accurate... lol

I have a 2.3L turbo in the garage that I might swap in at some point. A 4.0 would be nice but I'd need the engine, harness, and an M5OD, (Don't think the FM145 would hold up well.). I wouldn't say the 2.8L is the worst thing to happen, I myself had a Bronco II before with a 2.9L that was overheated before and had cracked heads...

 

[wildbill23c]

Sounds like it needs a major tune-up, carburetor adjusted, and that smog pump removed. Possibly you may need to replace the fan clutch as well, if that thing is stuck in the engaged position it will really drag down your fuel economy.

The 2.8L V6 isn't that bad of an engine, especially when you get to know your way around it and all of the little tricks. I'm still learning and I've had 2 vehicles with this engine.

That truck is in great condition for its age, get your truck tune-up and you can expect close to or slightly over 20mpg. I'm getting about 17mpg in 100% city driving with my 84 B2 with the 2.8L V6 so you should be getting close to that at least.

 

[Lil-Pony]

check the o2 sensor, pull the smog pump, clean all the wire connections, and do a basic tune up, air filter, premium sparkplugs, 9mm wires, rotor, cap

 

[jhammel85]

It needs a tune up for sure. Do it all and see where it sits then.

Also nice truck! I've seen you on FB.

 

[FordFanatic]

I've already adjusted the carb a little. Had to turn the mixture screws up, try we're only a quarter turn open and it was stalling out on me approaching stoplights. Plan on new plugs and wires definitely, probably a new cap and rotor too. Cleaned out the old paper air filter but that's still not a new one. I'm also curious on how to de-smog it without a duraspark conversion. I'm going to guess many things will need to be plugged...

 

[JoshT]

It could be the angle of the photo, but that tire size looks a little bigger than stock. If that's the case it could be throwing off your MPG calculations. Plugs, wires, distributor cap, rotor, hell I'd probably thrown in a new coil as well since the truck is 28 years old and I doubt it's been changed. Change fuel filter, check the timing, check or replace PCV valve. New air filter and make sure there are no obstructions in the breather tube. check over your vacuum lines for condition and leaks, replace if necessary. Can't tell you how to check the Emissions system or cats, they were deleted on my 2.8L long before I got the truck. That's all the ideas I can come up with for now, but I feel like I'm missing something.

My 84 Ranger got about 10 MPG, it was no where near stock and was way out of tune. It was a 2wd, but had over sized tires for the gearing. It had an offy intake, holley 4bbl carb, duraspark, longtube headers, dual exhaust, port and polish work done to heads and intake, aftermarket camshaft, and a driver with a heavy foot. I sucked at tuning carbs and never got that holley anywhere close to running right and was running really rich, but it was fun while I had it. I don't think I could ask for wildbill's numbers, but you should definitely be able to pill better than 10 mpg.

 

[FordFanatic]

No it's not the angle. It came with 215's and has 235's now. I drove it 17 miles today and the gauge didn't really move, so that's a plus. haha But yes it definitely wouldn't hurt to replace all the small things. I'm just hesitant on a cap and rotor since I'd like to do a duraspark swap before too long...

 

[enginepaul]

Do a tune-up and also pull the codes before you do any replacement stuff.

The stock TFI (in tune) will get better mileage than a duraSpark - the DruraSpark is just easier to work on and cheaper than trying to fix a system with lots of problems.

It looks like you have a good base truck to keep for a few years.

My Rangers got between 19 and 20 mpg all stock with mixed city and highway. (See the comment about tire size for MPG help)

 

[kimcrwbr1]

Clean the senser in the air filter housing with electrical cleaner IAT intake air temp senser, The read up on pulling the codes after you give it a complete tuneup. First thing to try is reset the computer and see how she runs. Disconnect the battery for at least 1/2 an hour while you make sure all the connectors are clean and all the sensers are plugged in. Check all the vacuum lines are clear and in their proper place. Only 40,000 that motor is just a baby if you can get all the smog working it will be a runner, closer to 18 plus in gas mileage. After you reset the computer it may take a couple complete warmups for it to set the new values on the computer. If it still runs like a pig pull the codes after you reset the computer and erase the memory. Address the codes in the order they come up fixing the lowest number first and then start all over again. Right now the best thing is clean all the electrical connectors, the IAT senser and then pull the codes. If you run it with a sensor disconnected the computer goes into limp mode and needs reset.

 

[FordFanatic]

I'm definitely gonna have to do that. Fortunately my dad brought home an EEC-IV code reader a few months ago. Is that sensor you're talking about the one at the front towards the pass. side on the air cleaner? Which one is the IAT too? But cleaning connections and resetting the computer is definitely a good idea. Thanks for the advice everyone!

 

[kimcrwbr1]

Intake air temp senser is the IAT is the only one that can be cleaned. Check the timing with the spout wire disconnected. On the wires coming out the distributor in a single wire with a connector disconnect it and the engine will run on base timing 10 DBTDC. Do not mess with the idle air needles on the bottom front of the carb. The computer controls engine idle you need to disable the idle control motor to adjust the needles correct. If you turned them first off turn them all the way in clockwise to lightly seated and count the turns out 3 1/2 turns as a preadjust. Bring the engine up to temp first make sure the choke is fully open and with a vacuum guage on the manifold vacuum, disconnect the idle control motor disconnected sdjust the needles for the highest lean possible vacuum pressure where if you turn it in it begins to drop. then plug the idle motor back in it should idle around 675 rpms.

 

[FordFanatic]

I do believe the idle was set down before, but the truck was stalling out on me as I approached stoplights. At a 675 rpm idle I think with the A/C on the truck would die. I'm guessing that rod in front of the throttle is what controls the idle. I'm not too concerned about tuning the carb as it's not running really rich, it doesn't blow smoke of any kind out of the exhaust. I'll have to play with that later but I think for now the carb has some decent settings. For now I'd like to play with everything else. Make sure there's no vacuum leak, clean the IAT, make sure the base timing is set correctly. Then figure out how to work the EEC-IV code reader and see what pops up...

 

[RICO9]

Everyone has given you some really good replies and they've pretty much covered everything you can do. However, these trucks are notorious for having bad fuel gauges. It can really though off your MPG calculations. I have an 84 B2 and it has a 23 gal tank and my gauge shows empy when I still have about 9-10 gallons left. Just something else to check. Nice Ranger by the way!