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Fuel mileage very poor?

Tiny
JESSESHAFFER
  • MEMBER
  • 1998 FORD F-150
  • 4.6L
  • V8
  • 2WD
  • AUTOMATIC
  • 280,000 MILES
My engine has less than 60000 miles on it. It's out of a wrecked 01 model. I'm only getting around 15 mpg on the highway. Check engine light is burnt out from the previous engine/ owner. I have codes related to emissions but not sure if all codes are related to one particular defective part. Could you help me with finding what's wrong without having to change out everything? Thank you.
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Monday, October 19th, 2015 AT 12:27 AM

64 Replies

Tiny
HMAC300
  • MECHANIC
  • 48,601 POSTS
If u are getting codes then it's either a sensor or wiring issue or both if not more. get back with the codes so we can sort it out. also the MAF sensor can go bad causing this issue.

https://www.2carpros.com/articles/how-to-replace-a-mass-air-flow-sensor-maf

Please run down this guide and report back.
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Monday, October 19th, 2015 AT 6:52 AM
Tiny
JESSESHAFFER
  • MEMBER
  • 8 POSTS
Codes are PO174, P1151, PO133, PO153, PO420, and PO1000.
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Monday, October 19th, 2015 AT 6:58 AM
Tiny
HMAC300
  • MECHANIC
  • 48,601 POSTS
What is fuel pressure?30-45 psi key on engine off
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Monday, October 19th, 2015 AT 7:25 AM
Tiny
JESSESHAFFER
  • MEMBER
  • 8 POSTS
My fuel pressure was about 25 with engine off. 26 at idle and 33 at full throttle going down the road.
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Tuesday, October 20th, 2015 AT 9:42 AM
Tiny
JESSESHAFFER
  • MEMBER
  • 8 POSTS
Also checked temp of catylactic converter after driving 70 mile trip. Temp was 280.
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Tuesday, October 20th, 2015 AT 9:45 AM
Tiny
HMAC300
  • MECHANIC
  • 48,601 POSTS
Check your fuel pump or regulator that is not enough pressure. It should be at least the figures I sent in last reply. See pic for regulator test. Also if you pull vacuum hose off regulator and it is wet replace it. If pressure is still low after regulator test( inother words if pressure goes up but not to spec) replace pump.
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Tuesday, October 20th, 2015 AT 9:50 AM
Tiny
HMAC300
  • MECHANIC
  • 48,601 POSTS
Converter temp doesn't mean a lot you mean it was 1280 not 280. That means it's running lean engine wise.
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+1
Tuesday, October 20th, 2015 AT 9:51 AM
Tiny
SCOTTANDHOLLY
  • MEMBER
  • 2 POSTS
  • 1998 FORD F-150
  • V8
  • 2WD
  • AUTOMATIC
  • 206,000 MILES
I have what sounded at first like the idler was not running smoothly due to worn bearings inside it. When I raise the hood and listen to the motor running it sounds almost like the noise is coming from inside the motor down at the bottom near where the fan connects to the motor. When I accelerate, the vehicle hesitates at around 25-30 mph, then accelerates as normal. I have also noticed a decrease in fuel economy. Any suggestions?
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Thursday, September 3rd, 2020 AT 2:24 PM (Merged)
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,755 POSTS
Hi:
If the sound is coming from the fan area, it sounds like the water pump is bad. Check for evidence of leaks around the pump itself.

Let me know what you find.

Joe
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Thursday, September 3rd, 2020 AT 2:24 PM (Merged)
Tiny
GIMMIGEE
  • MEMBER
  • 1 POST
  • 1997 FORD F-150
  • V8
  • 2WD
  • AUTOMATIC
  • 118,000 MILES
Poor mileage and pickup, always hear spark knock even with higher octane fuel
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Thursday, September 3rd, 2020 AT 2:24 PM (Merged)
Tiny
MERLIN2021
  • MECHANIC
  • 17,250 POSTS
Last tune up? With a new PCV? Check for vacuum leaks, get a can of spray gumout, spray vacuum lines and around the intake manifold, if the idle changes, you have found a leak!
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Thursday, September 3rd, 2020 AT 2:24 PM (Merged)
Tiny
PREACH228
  • MEMBER
  • 1 POST
  • 1996 FORD F-150
  • 6 CYL
  • 2WD
  • AUTOMATIC
  • 135,000 MILES
I just bought 1996 Ford F150 xl single cab automatic with o.D., Air with 133,000 miles. It runs great. I checked my mileage after a trip and almost had a heart attack. All I got was 10 M.P.G. What's the deal? How can I improve it?
Thanks,
Dissapointed Mike
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Thursday, September 3rd, 2020 AT 2:24 PM (Merged)
Tiny
BLACKOP555
  • MECHANIC
  • 10,371 POSTS
Maybe needs a tune up.

Check tire conditoins for sign of out of alignment. Under infalted tires.

May need new fuel filter and air filter.

Run a few cans of seamfoam through the gas tank with the gas tank low.

Then check the o2 sensors and replace as necessary. That should get the vehicle back on the road.
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Thursday, September 3rd, 2020 AT 2:24 PM (Merged)
Tiny
JOHN ZUMBRO
  • MEMBER
  • 1 POST
  • 1995 FORD F-150
  • 6 CYL
  • 2WD
  • AUTOMATIC
I have a 1995 ford f150 with a 300 six cylinder motor
it is fuel injeteded and has two tanks a front and rear. I have been using the rear tank because the front tank fuel pump has went out. So I drained the front tank and run off the rear tank only. Now here is my proublem my fuel milage has dropped using the rear tank and my front tank is now full agien with fuel and I have not added any fuel to it but every time I empty it out it seems to refill itself?
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Thursday, September 3rd, 2020 AT 2:24 PM (Merged)
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,755 POSTS
There is a service bulletin out regarding this problem. The rear tank's fuel is getting pumped into the other tank. Contact your local Ford dealer regarding this problem. It deals with the cross over.
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+2
Thursday, September 3rd, 2020 AT 2:24 PM (Merged)
Tiny
DRIVER7006
  • MEMBER
  • 1 POST
  • 1994 FORD F-150
  • V8
  • 4WD
  • AUTOMATIC
  • 110,000 MILES
My 1994 f150 4wd is getting realy bad fuel mileage we have changed fuel filter spark plugs and have also ran a can of sea foam through the vacume line and in the fuel tank it seemed to run better but I still have hesitation in take off and bad fuel mileage can you help
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Thursday, September 3rd, 2020 AT 2:24 PM (Merged)
Tiny
CJ MEDEVAC
  • MECHANIC
  • 11,004 POSTS
See my profile. Imma CJ GUY, have really no experience with your rig

All kinda factors may be in play, So I will will give you some common to all CYBER-RIGS such as yours and my wifes Escape.

These are tips and hints out of her manual, and a few of my own

Does your check engine light---affirm it works when cranking up?

Either case, you might get coded for present or stored codes you may have. Advance Auto or Autozone will do this for FREE. If you have a problem, your computer may be compensating (just to keep you running) But unable to receive "Real World" values to make you EFFICIENT, such as O2 or Temperature Sensors (investigate open or closed loop on a cyber-rig)

Are you stock. Or trying to be BIGFOOT?

Do you drive like Grandma or Charles Manson would, if he could?

Do you FREQUENTLY haul around Large Heavy Items? (I drew the picture, you color it in, any way you wish!)

Do you have an OWNERS MANUAL or a REPAIR MANUAL for your rig?

Do you keep up with ALL SCHEDULED MAINTENENCE? (Detailed Operations in Haynes or Chilton manuals)

Air filter dirty?

Tire pressure?

Does anything here apply to you?

Respond

The Medic
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Thursday, September 3rd, 2020 AT 2:24 PM (Merged)
Tiny
2CP-ARCHIVES
  • MEMBER
  • 4,540 POSTS
  • 1993 FORD F-150
  • V8
  • 4WD
  • AUTOMATIC
  • 114,000 MILES
1993 Ford F-150 4 WD mileage: 114,000. My truck problem is rough Iidle, poor gas mileage, hesitation, after a short drive (ten miles) or so, if I shut the engine off and restart, the motor is hard to start and about one mile down the road the check engine light comes on. I took my truck to several mechanics and have replaced the throttle position sensor, 02 sensor, water temperature sesnor, They got me an Emissions sticker but the problem still remains. I recently used the truck's self-diagnostic tester and the following results (codes) were obtained. KOEA: 31-EVP circuits below minimal voltage. KOEA: 32-EVP voltage below closed limit. KOEA: 33-EGR valve not opening. KOEA: 41-O2 sensor not switching. RUN CODE: 21-No idea what this one means! RUN CODE: 44-Secondary air inoperative. RUN CODE: 33-EGR valve not opening. I'm trying to follow a Haynes manual, and not sure where to go from here, and need some advice! Thanks for the help!
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Thursday, September 3rd, 2020 AT 2:25 PM (Merged)
Tiny
2CP-ARCHIVES
  • MEMBER
  • 4,540 POSTS
Check the fuel injectors to be sure one is not hanging open or leaking. Check fuel pump pressure and fuel pressure regulator. Check the voltage generated by the oxygen sensor; the range should be.5 to 3 volts
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Thursday, September 3rd, 2020 AT 2:25 PM (Merged)
Tiny
505DANIELM
  • MEMBER
  • 15 POSTS
  • 1993 FORD F-150
  • V8
  • 2WD
  • AUTOMATIC
  • 122,000 MILES
My 93 F150 has a 5.0 with AOD. I bought it in 1995 and was getting 16-17 MPG consistently in town. Now I barely get 10 MPG city or hiway. I had to replace both fuel pumps because when I ran off the front tank fuel would return to rear and pressurize the tank. I've replaced plugs, wires, rotor, dist. Cap, PCM, fuel pressure reg, catalytic conv, all fuel injectors, O2 sensor, and more. It doesn't use any oil, if the motor was shot I would expect oil consumption. After replacing the O2 sensor, I can drive 200 miles and it will blacken it so it is running VERY rich. The exhaust system was very black. I live in a city with 5,000 ft elevation and pull 19 on a vac gage, so I don't think there's any vacuum leak. The computer doesn't set any codes. Base timing is normal. Trans. Is working normally, brakes are fine. Shops in town tell me 10 MPG is "normal". A 40% drop in gas mileage is NOT "normal". What could be wrong, faulty ignition? Poor gas mileage?
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Thursday, September 3rd, 2020 AT 2:25 PM (Merged)

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