2001 Ford F-150 Alternator

Tiny
PODA13
  • MEMBER
  • 2001 FORD F-150
  • 6 CYL
  • 2WD
  • MANUAL
  • 130,000 MILES
My battery light recently came on and after much testing of the battery and cleaning of the terminals, came to the conclusion that it was my alternator. I replaced it with a 130 amp new alt. In which after installing it all voltage and amp readings came back perfect. The problem I am having now is that my truck is now running rough and my gas mileage dropped from 17.5-18.5 down to 12.5. My style of driving was the same. When I accelerate it hesitates a little and the ride is a little rough. I recently replaced my plugs, wires, and coil pack with motorcraft parts for another misfire as read by my code reader. The question being is the drop in mileage and rough ride due to the new alternator? There are apparently 2 kinds for this style of truck, a 130 and 95 amp. The new one I bought is the 130 amp and looked identical to the old.
Tuesday, September 7th, 2010 AT 8:04 PM

7 Replies

Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 110,176 POSTS
That shouldn't have anything to do with gas mileage. Also, I believe the pulley size is different. Therefore, the belt wouldn't have fit properly.

Has the check engine light come on? Also, when installing the alternator, by accident did you disconnect any vacuum hoses or forget to reconnect them?

Let me know.
Was this
answer
helpful?
Yes
No
Tuesday, September 7th, 2010 AT 10:20 PM
Tiny
PODA13
  • MEMBER
  • 4 POSTS
J&N,

The check engine light has not come on and the belt fit perfect. When I installed it I did not need to disconnect any vacuum hoses, however I will check first thing in the morning to make sure none of them are loose. But if a hose came loose, the engine light would come on throwing a code, which has not happened.
Was this
answer
helpful?
Yes
No
Tuesday, September 7th, 2010 AT 11:13 PM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 110,176 POSTS
In some cases it will set an engine code. In others, it won't. Just for the heck of it, check it out. Hopefully, it will be something that easy and cheap to repair.
Was this
answer
helpful?
Yes
No
Wednesday, September 8th, 2010 AT 12:45 PM
Tiny
PODA13
  • MEMBER
  • 4 POSTS
So I checked all the hoses and the connections to the alt. And everything appears to be in shape. Still not sure of what to do. I looked at the ford website using my VIN and it displayed both the 130 and 95 amp. Would using the 130 amp when the truck came with a 95 amp cause problems? Stupid me didnt check the part # before I used the old as a core so I cant check.
Was this
answer
helpful?
Yes
No
Wednesday, September 8th, 2010 AT 8:54 PM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 110,176 POSTS
It shouldn't hrurt becuase it is regulated. However, a 95 amp may not work in place if the 130. I'm just surprised it fit properly if it is the wrong one. Call the parts store and ask them to compare the two side by side to see if there is a different. That way you'll know if there is a difference, you got the right one.
Was this
answer
helpful?
Yes
No
Thursday, September 9th, 2010 AT 9:32 AM
Tiny
PODA13
  • MEMBER
  • 4 POSTS
With everything looking good I will just head down there and look at them myself side by side and figure. Oddly enough though, it ran fine on the way home from work this afternoon. Not sure. Thanks for your suggestions!
Was this
answer
helpful?
Yes
No
Thursday, September 9th, 2010 AT 10:35 PM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 110,176 POSTS
Let me know what you find.

Joe
Was this
answer
helpful?
Yes
No
Friday, September 10th, 2010 AT 11:03 PM

Please login or register to post a reply.

Related Alternator Test Content

How to Test an Alternator
VIDEO
How to Test an Alternator
Instructional repair video
Alternator Test
GUIDE
Alternator Test
The alternator in your car is designed to generate voltage at prescribed amperage which is designated by a voltage regulator or vehicle computer. This electrical energy...
VIEW MORE