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Brad, ASE Certified Technician
Category: Ford
Satisfied Customers: 2366
Experience:  ASE Certified Master Technician
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1995 f150: loses power like it is running out of gas

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my 1995 f150 loses power like it is running out of gas . had it at 3 places and is still not fixed. put on computer all 3 times .the check engin light comes on . the oxygen cencer was replaced 3 times, then it will be ok four about a week then it starts all over again. it dosent seam to have all its power when it does run for that week. please help,i am going broketrying to get this fixed!! it is a 5.0L,auto.4by4

We have seen this problem many times. The following needs to be checked.


Get a volt meter on the O2 signal wire and see if the meter agrees with the DATA.

If the O2 signal circuit has 1.13 V on it, try unplugging the O2 sensor from the harness and see if the voltage on DATA drops to 0.0 V.

If the voltage changes, check the O2 harness connector for corrosion.

Clean or replace the connector as needed.

Customer: replied 7 years ago.
Relist: did every thing that jim told me to do before he told me to do did not work then so it can not be that. could it be the cat????.
did every thing that jim told me to do before he told me to do did not work then so it can not be that. could it be the cat????
Lots of things can cause your issues... MAP sensor, Throttle Position Sensor, bad computer..

You mentioned your engine light was on.. do you happen to know what codes were set?

Edited by Brad on 8/24/2010 at 4:15 AM EST
Customer: replied 7 years ago.
but what is causing the o2 sensor to go bad? after i replace the o2 sensor it is ok for about a week then something is making it go bad again. this is my third o2 sensor.
It depends... how are you positive the O2 sensors are bad? Are the bad electrically, or are they bad physically?

Does your truck smoke out of the tailpipe any? Oil or Coolant in the exhaust can kill an O2 sensor real quick.
Customer: replied 7 years ago.
brad,we checked allof that also. no water or oil!! oil is ok and dosent burn oil. never haft to add oil from one oil change to the other. same with the collant. i am not shure the o2 sensors are bad ,but as soon as i put a new one in its ok for about a week to 10 days, then it starts all over again
OK.. before I can even begin to help further, I'm going to need to know what codes are stored in the computer.

As for the O2 sensors.. I would unplug them and double check the terminals at the connector.. make sure none are pushed back.. or bent.. or corroded.. etc. Also, if you've been splicing in 'universal' sensors, then you need to make sure you're splicing into the correct wires, and that you are SOLDERING them together and using shrink wrap to properly seal the splices so they don't get contaminated with moisture.

You also need to physically inspect as much of the wiring as you can, to make sure none of it is laying against the exhaust somewhere and melting... or coming apart.. or whatever.

O2 sensors can also get contaminated and fail if the engine is allowed to run rich. It's possible you have another problem going on (such as a ruptured fuel pressure regulator.. injector sticking.. low compression..ignition problem, etc) that is allowing unburned fuel into the exhaust, and after awhile the O2 sensors get so saturated with it that they can no longer function correctly. They will usually clean themselves up once the engine stops running rich... but it's still possible that something else entirely is causing your O2 sensors to fail.

You mentioned that even with it's 'fixed' it still doesn't seem to have full power... that sounds like it's not running on all 8 cylinders... I would suggest that you chase the misfire before continuing.

You can also try removing the O2 sensors and drive it around the block. Yes it will be VERY LOUD but if you notice that the power has been restored, then there's a good chance that the catalytic converters are all plugged up (and you have power now because the holes opened with the O2 sensors being out allow it to breathe).

So you see there are still many possibilities here.. I feel the O2 issues is a result... not a cause.. of your problems.
Customer: replied 7 years ago.
brad, i agree that the o2 sensor isnot the cause. the only thing wrong with unplugging the o2 sensor is it will run great one minute and then start acting up the next minute. it does not run bad all the time . it comes and goes. i realy appreciatetour help!see if u can come up with something else?then i will pay u... thanks
Customer: replied 7 years ago.
brad, this truck only has one o2 sensor. this is all factory.does that mean any thing?
No it doesn't change anything.. you need to chase down why the truck is running rough, even with a new O2 sensor. This is probably what keeps causing them to fail.

You need to start back at the basics... check for fuel pressure, spark, compression. If you have one cylinder that has a significantly less amount of compression than the others (more than 10% less), then that cylinder isn't burning all of its fuel and pushing it into the exhaust, which can cause the O2 sensor to start failing.
Brad, ASE Certified Technician
Category: Ford
Satisfied Customers: 2366
Experience: ASE Certified Master Technician
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