need help

[4x4&2wdprerunners]

i just got a 1986 ford ranger 2.9L and i just bought a new altnator and for some reason if dose not want to charge it sits at 12v for about 5min and the slowly goes down in i dont have and thing on soi need help if any one can help me on it..

 

[Hotrodlincoln]

Voltage regulator may be bad. Get a Chiltons or Haynes manual for the truck. It will help.

 

[kimcrwbr1]

take it off and go to a part store to have it tested, I believe it has the voltage regulator in the alternator you can go to the tech library and look under charging system for more info

 

[4x4&2wdprerunners]

i went today and had it tested and its all good so what else can cuase it not to charge its really making me mad

 

[IMenriched]

i went today and had it tested and its all good so what else can cuase it not to charge its really making me mad

bad cables....poor ground....slipping belt...poor connection

 

[4x4&2wdprerunners]

what else can it be i checked allthe wires and its all good

 

[Big Jim M]

Ok lets test it

what else can it be i checked allthe wires and its all good

What are you baseing your volts on? Do you have a seperate volt meter or are you judging the volts from the stock gauge? Sometimes the stock gauges go haywire..
With a seperte voltmeter check the volts at the battery.. Idle first and then about 2,000 rpm.. Then idle with the head lights on and again at 2,000 with the headlights on..
It is good to use the voltmeter yourself and have someone else to operate the rpm.. You will have a good idea when the output of the alternator changes from discharge to charge with the lights on...if it ever does discharge..
Big JIm

 

[4x4&2wdprerunners]

i have a volt meater that i put on the batt and it sits on 12v and when u go to high rpm the volts drop. and i dont have head lights on so it will not keep my batt chargeed.

 

[Big Jim M]

Ok then turn the headlights on and watch them as the engine is run up.. Just to make sure your volt meter is good. If the alternator is putting out the lights will brighten..
Big JIm

 

[IMenriched]

Is this alternator one with an external regulator?

 

[4x4&2wdprerunners]

the volt meter is internal and i am useing a 300 doller muilt meter and it only does 12v and will go down slowly

 

[IMenriched]

the volt meter is internal and i am useing a 300 doller muilt meter and it only does 12v and will go down slowly

sounds like you have a parasitic drain....else where in the system. the alternator simply can't keep up.

is the battery always low/drained? can the battery hold a charge? In Other Words, is it good?

good grounds here can not be stressed enough

 

[4x4&2wdprerunners]

batt is new and if i let it sit it does not drain the batt but it juft will not charge

 

[BeefStew42791]

if you ever find out why your truck's doing this then I'd love to know what it was, because I've got the same problem in my 93 4.0 and I can't find the problem either.

 

[dawson111299]

so if its draining slowly do you have to jumpstart it or charge the bat all the time if so i suspect the inline fuse from the alternator . Try this start the engine disconect the bat pos and see if it dies out drops rpm