Fuel mileage very poor?

Good that means it is good. I never assume that a new part is alway's good as you can get bad ones sometimes. So now I would like to test the MAP sensor. First unplug the vacuum line to it after you have it warmed up for about a 3 minutes and at idle if you unplug the vacuum line does it go rich and try to die? If it does great. Otherwise I need you to get you volt meter and you need to know about what you elevation is and check you signal return (refer to pic below) and get back to me with the elevation and voltage you found there with truck running ok. I also need to know if your truck has a mass air flow meter or not. They come both ways through 95. Get back to me and we will go from there.

Engine Mechanical problem
1992 Ford F150 V8 Four Wheel Drive Automatic 229+ miles
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I am going nuts PLEASE HELP ME!!!!! Fuel is almost $4.00 a gallon and my truck only gets 4mpg. No exaggeration, no bs, honestly this is my actual gas mileage. I realize it is extremely high mileage 229,268.09 miles. It starts easily, she is a good girl that way, and at times will run like a dream down the freeway, seems tho that she has gotten extremely ill and I have to always have the overdrive button on the column shifter I don't have anyone to help me with this so I am trying to wade through all the symptoms. It cuts out badly, the fuel usage is unbearable. Going up inclines seems to be the roughest on it. Using cruise control does seem to help it to even out and not run so roughly. I have been told it could be a sensor, or the fuel pressure regulator. Now I have been told that it takes a special tool to change the fuel pressure regulator. But this is coming from someone that wants me to sell it and I am determined to fix my truck. Can anyone give me any advice?? Thanks. I need to know where to locate the regulator and what tools would I need to perform the task? I cannot afford a mechanic, and am now working only to pay for gas to and from work. HELP!!!

You might want to do some mechanical work on your truck. If you have then disregard my next statements and make sure your 02 sensor and EGR are working properly. A valve job will help enormously if they are not seating correctly due to carbon buildup. A timing chain and camshaft will help compliment. As you might have guessed next you need to do a compression test on your cylinders but my guess is you have far too much blow by past the cylinder rings. Change the rings or the pistons and rings accordingly. To be honest a properly tuned carburated car should get around 10-15 mpg and an EFI motor should recieve 15+.

Is there any kind of smoke coming from the tailpipes? Has work been done to it lately?

have a 1991 f150 sc 4x4 auto. gas mileage is real bad and power not great. even at 55 mph gas mileage is still about 9 to 10 mpg. any suggestions. no check engine light

Which V8 do you have?

sorry. the engine is the 5.8 litre or 351

With that engine, MPG were always really low. Usually, they averaged around 11. The only thing I can suggest is to make sure the air filter is clean, and if it has been a long time, a tune up may help.

I struggle with MPG with the 5.4L I can average 11.5, my wife, on the other hand, averages 9.8. But she doesn't have a lead foot (so she says).

i was afraid of that. thank you for looking into it

Glad to help... I just wish I had better news.

I have a 1990 Ford F150 that runs excellent, except that it only gets about 7 to 8 miles per gallon on the highway. We have changed the plugs, wires and distributor cap with no change. I also put it on a code reader, and it did not throw any codes. The check engine light only comes on when you turn the ignition key on then goes off when the engine starts. This truck always got between 15 to 18 mpg until about a year or so ago. Needless to say, we don't drive it much. Thank you in advance for any help you can give. MEL

Have you checked for leaks? Have you checked the fuel pressure regulator? Have you checked for plugging of the catalytic converter? Is there any drag on the vehicle such as a stuck brake?

No on all of the above, but beginning this morning I will be doing so. Thanks for the advice.

Let me know what you find.

No leaks and no dragging brakes. I had the catalytic converters checked by a shop, with negative results. We will be checking fuel pressure today or Monday. I was also told by the shop that I should check out the O2 sensor.
That is also on the agenda.

The O2 sensors could be an issue too. However, that should have set a trouble code. Have you checked for any?

uses at least 5 times what it should,1/4 tank = 20 miles

Start with a compression test and a full tune up and do an economy test, fill the tank do 100 Miles, and re fill this will give you an accurate economy reading, if you want just do 50Miles and re fill same thing same readings

Re excessive fuel consumption
Truck starts and runs fine,has about 50,000mi on factory rebuild,trans is rebuilt as well, I was thinking is this a fuel pressure regulator issue?
I also looked for a maf in the air intake, bur was unable to find it,likely because it doesn't seem to have it,I recharged k&n air filter and may have reinstalled it a bit wet,however I believe the engine was allready a pig on fuel. I had locking gas caps on the vehicle but noticed the fuel hissing out the filler spout and so I put the old gas caps back on.also I was wondering about the carbon canister any advice would be great,there are no services where I live Thank you..... Wally

A faulty pressure reg will increase fuel consumption, you need to check this wit a pressure gauge, with the gauge hooked up and the engine running, the fuel pressure should go up with the vacuum hose disconnected and drop when re attached, check this out.

can adding pure acetone to your gas tank give you better mpg and will pure acetone damaged any part of your truck

I thought I heard of everything when a relative starting adding mothballs to his fuel. First of all, you didn't dream this up on your own. Someone else came up with the idea and you heard or read about it. If it really had some advantage, you can be sure word would have spread and everyone would be buying acetone.

As for damage, unless someone else has knowledge related to additives, I can suggest that the lead in leaded gasoline of the past acted, among other things, as a lubricant for valves. We had a lot of valve and seat problems for a couple of years when lead was removed until metal alloys and fuel additives got better. Thinking along those lines, I doubt there's any lubricating properties to acetone. I've used it as a fast drying cleaner so I know it vaporizes easily. It's not needed as a fuel system cleaner. The current detergents in today's fuel does a real good job, plus gasohol contains alcohol which cleans the fuel system.

You might consider whether acetone burns hotter than gasoline. If it does, it could melt the electrodes off the spark plugs and promote overheating the catalytic converter. If it doesn't, misfires could result with that unburned fuel burning in the converter and again, overheating it.

My recommendation is to stick with the fuel your engine was designed to run on, . . . gasoline. If any manufacturer could come up with something that gave better fuel mileage or power than their competitors, you can be sure they'd incorporate it into their vehicles.

You Tube has some stuff too

I have tried many tricks on my Jeep (the ole tornado, and several other gimmicks)

The most rewarding was installing a O2 sensor and a "Air/ Fuel Ratio Gauge" and using my in dash "Vacuum Gauge" to help me select the best Jets to run in my Carb, and power valve...As traditional ways I was shown, left too much guessing and error, in my eyes, anyway, I had been trying to achieve at minimum a 10% MPG gain, as promised by other carbs and gimmicks

I kept accurate adjustment and tuning records for nearly 2 years in my logbook....I was about to give up.

My Jeep is Heavy, I carry way more crap than the average Joe (I need it, I got it!)....we weighed removable crap, and guessed at other stuff, my buddy and I came up with 400-500 lbs. Brush guard, rear "air tank" bumper, 80' 3/8 cable, 5 extra gallons fuel, 21 gallon over-sized fuel tank, air compressor, train horn, door steps, tools, spare parts, 3 coats, food, water, ax, shovel...and more!!!

There's no tellin' what I might gain if I were the "unprepared type"

Right now 18, MPG w/ Holley 390 CFM 4 bbl, that's about 2 more MPG than with the stock 2 bbl BBD, and I was much lighter, when it was on!

Mega power, if I get on it, and MPG, I've never had before...all on my 258, 6 cylinder!!!





Hope this helps

The Medic