I am experiencing Dismal fuel Economy, I filled the tank about 16 gallons (tank read full) and went 118 miles, I burned to about 1/4th of a tank remaining, so a rough estimate is I burned 12 gallons of fuel to go 118 miles, leaving me 5-8MPG Cruising 50-60 miles an hour.... What should I be looking for..... I have 110,7XX on the truck. it's slow as heck, it hesitates and just has no get up and go unless you really step on it. It's had a recent tune up. Plugs were changed at 105,000 miles roughly.... I'm at a loss to know why this little truck is burning so much fuel. It's the 6 Cyl Flex fuel engine. with just normal fuel run in it... any ideas? I've looked at night for arcing wires and there's no flashes... there is no real miss, I checked the intake for pirate air and fixed one minor leak and have recently rechecked it as well...I've not pulled the plugs out again yet.... any suggestions?

Let me know if my MPG estimations are off some. math is not my strong suit but it's a rough estimation...

* This was half freeway half backroads

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hum.....
1987 300TD 311,000M Stolen. Presumed destroyed

12 gallons for 118 miles is just a little under 10 mpg - I'd hazard you ought to be hitting at least 20 mpg with a V6 Ranger, if not more.

How did the truck run prior to changing the plugs? IOW, is this a recent development? Knowing a little more history of how the truck has behaved would help.

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Just say "NO" to Ethanol - Drive Diesel

Mitchell Oates
Mooresville, NC
'87 300D 212K miles
'87 300D 151K miles - R.I.P. 12/08
'05 Jeep Liberty CRD 67K miles
Grumpy Old Diesel Owners Club

First off, do an actual check of the mileage.
Fill the tank. Drive. Hit a nearby interstate and verify that the odometer is reading true. You can also use the mile markers and a watch to verify the speedometer is close--60mph is 1 mile per minute. Refill the tank at the same pump with the truck facing the same direction. mpg= the miles you drove ( corrected by what you found out when you drove on the interstate), divided by the gallons used on the second fill-up.

Using the fuel gauge, especially on a Ford, to estimate how much gas you used is bad data. On most Ford trucks I have had, the gauge drops like a rock to 1/4 tank, and then hangs there a while.

If its really using that much fuel, the "check engine light" (CEL) should be on because the computer should know something is wrong. By the way, does the CEL come on for a few seconds when you start it up, and then do out? If not, look for a bad bulb, or worse, a truck that has been hacked up.

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1982 300SD " Wotan" ..On the road as of Jan 8, 2007 with Historic Tags

I recently sold an 86 Ranger 4 wheel drive that we mostly used here around the farm, with the very occasional trip into town. Nice little truck but I don't think it ever got 10 mpg, even downhill with a tailwind. Didn't use it enough the last few years to worry about mileage but it didn't seem to do much better than the F800 dump truck (6-8 mpg), just the way it had always been.

Jim

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2005 C240 4matic wagon (daily driver)
87 190D - 225K (on loan)
85 190D - 312K (on loan)
2011 Subaru Legacy AWD (Wife's)

These are the best sources of online information for your vehicle.

Ford Explorer and Ranger Enthusiast Forums - Serious Explorations

Ranger & B-Series - Ford Truck Enthusiasts Forums

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1987 560SL
85,000 miles

Even after I put a lift on my 3.0 Ranger I was getting 17 MPG so something is way off.

I would suspect that the coil pack may have failed. I went thru two in about 20,000 miles on my truck and when it was weak I had horrible mpg.

No CEL? Something must be telling the engine to dump fuel. No fuel smell?

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You don't need a weatherman to know which way the wind blows - Robert A. Zimmerman

Is the intake sucking air? It's not uncommon on these trucks, due to the material that is used to make them.

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1987 560SL
85,000 miles

have a look at the air flow meter. its very comon for them to get dirty and give an artificially low air flow signal resulting low power. you can clean it with brake clean.
were the plugs bosch platinum? i dont know why but those things do wierd stuff to engines. it might be worth changing them out for some other brand.

Odometer agrees with my GPS unit. Filled the truck back up and took 11.9 miles to reach full tank again (one click)

I'll go through and see what the plugs are. I was given a set of Autolite plugs with the truck. I have no idea whats in there right now. I had planned on replacing the coil and wires to see if my hesitation problem went away. I was also going to clean the throttle body but there's a nice sticker on it that says do not do, do thats out for now.

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hum.....
1987 300TD 311,000M Stolen. Presumed destroyed

I agree with MS - first thing we'd need to know to help is, is the Check Engine light even working in the first place?

I find it hard to fathom that a Ford truck of that era could be running that poorly and not throwing CEL's and codes. Do the check of the light at startup as he described - if that light is indeed burnt out, it could be throwing codes left and right and you'd never know it.

Second, if you know someone with a decent code reader that can also display live data when the engine is running, pay them a visit and have them hook it up to your truck - might just tell you in short order what's going on with the beast. If nothing else, if it is throwing codes, it'll help narrow down the list of possibilities.

Again, can you tell us how the truck ran BEFORE the plugs were changed? If it ran fine prior to the tuneup, this is a strong indicator that something done during that tuneup caused the problem.

Strong possibility that whoever gave you those Autolite plugs gave you the wrong plugs or ones with the wrong gap setting, given you said it's a Flex Fuel engine.

On my father's 98 F-150 with a 5.4 L V8, just for that engine alone, there's at least 3 different plug types/gap settings depending on whether it's natural gas, flex fuel, or a regular gas engine.

Back in '07, his truck ran like crap after he had a guy do a tuneup on it. After going thru the other possibilities, I finally pulled the plugs and checked them - that idiot had installed the plugs for a natural gas engine (it's a regular gas engine), and between the 8 plugs, they were gapped to THREE different gap settings - NONE of them even close to the correct setting for that engine.

Definitely need to do some detective work first, to narrow down what's going on, because if it's anything like this 98 F-150, there's literally at least a dozen possible causes that could be contributing to this.

__________________
Just say "NO" to Ethanol - Drive Diesel

Mitchell Oates
Mooresville, NC
'87 300D 212K miles
'87 300D 151K miles - R.I.P. 12/08
'05 Jeep Liberty CRD 67K miles
Grumpy Old Diesel Owners Club

i have a code reader. I'll take it for a drive and take some snapshots. post the results. CEL works. the bulb does anyways.

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hum.....
1987 300TD 311,000M Stolen. Presumed destroyed

Is it running at the right temperature? Wouldn't a cold engine cause overfueling?

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1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13

my reader refuses to do freeze frame data.... irksome

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hum.....
1987 300TD 311,000M Stolen. Presumed destroyed

Have you considered that the cat/conv is plugged up? A exhaust shop can do a backpressure test by taking the O2 sesnsor out and using a special guage.

You can also use a vacuum guage to do some diagnostics as well.

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"I was a dirty bird, Carol's not grungey - she's *****in" John Milner....American Graffiti