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Why wont or cant anyone seem to help my problem?

1357 Views 11 Replies 6 Participants Last post by  1996mustang
I am having a voltage problem when the car is brought above 3k rpm it drops about half of normal running. The alternator is a year old and i know there is such things of defects but i had the wiring checked and the alternator. Any ideas at all.
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Get the alternator checked out even if its a year old. Autozone pepboys normally do free alty tests. And when you go above 3 k rpms it goes down half normal by saying that what do you mean exactly. Trying to get more details so all of us can help a brother/sister in need with his/her car.

---------- Post added at 08:30 PM ---------- Previous post was at 08:28 PM ----------

I did just read that you had it checked out but by who exactly. Anothee thing could be something taking a load that could cause a drop in voltage like the ac being on or the fans kicking in around that rpm.
No because autozone bench tested it. Was fine and not that because i can be in park and rev the motor and the same happens even when not under a load. Driving me nuts.

---------- Post added at 07:10 PM ---------- Previous post was at 07:07 PM ----------

The stock voltage is at half way between 8 and 18 but when revved it drops a lil above 8 i would say about 10 or 11 volts
Ac on or off? Its odd if at 3k it starts doin it unless its the fuel pump drawing alot at that rpm then maybe the pump could be the culprit. Any accessories on? And did it start happening after u did some work on the car or jusg out if random and has it affected drivability and if so how
No because autozone bench tested it. Was fine and not that because i can be in park and rev the motor and the same happens even when not under a load. Driving me nuts.

---------- Post added at 07:10 PM ---------- Previous post was at 07:07 PM ----------

The stock voltage is at half way between 8 and 18 but when revved it drops a lil above 8 i would say about 10 or 11 volts
The generator or wiring are bad. The most likely being a bad ground connection, though it could be the + feed between the generator and the battery.

You need to check the voltage drop between the generator output terminal and the battery + terminal, and the drop between the generator body and the battery negative terminal--these should both be no more than 0.5V. To do this using a digital multimeter place one probe on the generator output and one on the battery + post; and then one probe on the generator body and the negative post.

The primary ground strap for the engine block runs from the battery to the block just behind the oil filter adapter, it is not uncommon for that connection at the block to corrode or come loose--check it first...
I would try resetting computer.(unhooking battery)
Check grounds and all connections are good
Ac on or off? Its odd if at 3k it starts doin it unless its the fuel pump drawing alot at that rpm then maybe the pump could be the culprit. Any accessories on? And did it start happening after u did some work on the car or jusg out if random and has it affected drivability and if so how
I do have a walburro 315 fuel pump actually and acc nothing much full msd,blaster coil, nitrous set up, gauges six of them and its 50 degrees out lmao no ac yet. Its a fully built stroker motor setup internally balanced the whole 9 yard you know. But yes after all the work. Think i need to add a bigger alternator to the car?

---------- Post added at 11:18 PM ---------- Previous post was at 11:16 PM ----------

ThAnk you guys will check all possible things then if i get nowhere i will have to go with a bigger alternator.
It may just be the voltage regulator. They can cause your symptoms and still test ok.
It may just be the voltage regulator. They can cause your symptoms and still test ok.
+1 i thought that too. If you rev your engine when its ok park and the lights get brighter then your regulator is bad
If you go to my website (click here), and use the sidebar menu to select Shop Manual Docs|Electrical|Charging System (see below) you can get the system tests and diagnostics for the charging system:



Charging is not controlled by the PCM as with some other Ford models, it is a standalone system independent of the PCM.

The starting system diagram can also be downloaded from that same menu.
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So it might be u need a bigger alty like a 140 amp if you got all those goodies. Well atleast we are making some progress in whats going on with your car
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