94 Ford Ranger-alternator problems

Tiny
VICKIAYALA
  • MEMBER
  • 1994 FORD RANGER
  • 4 CYL
  • 2WD
  • MANUAL
  • 247,000 MILES
Just letting you guies know on that 94 ford ranger. We changed alot of things you and others suggested. Nothing changed, then I unpluged the alternator and it ran fine. Changed it out 3 times. It's showing 14+ volts. Maybe the PCM is back they say. Who really knows? Two weeks stuck out of town with no answers because no one can figure it out. HELP if you can!
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Friday, April 1st, 2011 AT 4:25 AM

10 Replies

Tiny
CARADIODOC
  • EXPERT
What's the question?
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Friday, April 1st, 2011 AT 5:17 AM
Tiny
VICKIAYALA
  • MEMBER
94 Ford Ranger 2.3 stnd 2wd, ******, backfirers loses power going up hill, lifters clattering and almost dies. Unplugged the alternator (bought in Jan.) It runs greate like there was never a problem. Changed the alternator 3 times, different auto even, and it still****** and all when its pluged in. Unplug it runs fine. Checked the voltage output about 14.3. What is causing it to do this, does anyone have any idea what I can do to fix it? Please help me I'm stuck in Austin, Tx and I live down by Houston. Running out of money and ideas to fix this crazy truck. I really would appreciate if someone has a solution. Sincerely Vicki
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Saturday, April 2nd, 2011 AT 5:51 AM
Tiny
CARADIODOC
  • EXPERT
I hate to have you replace random parts but part of the problem could be the battery. That is a REAL common problem with GM vehicles but I haven't really heard of that on Fords. GM generators develop a lot of voltage spikes that interfere with the Engine Computer's sensor signals. A good battery dampens and absorbs those spikes. Sometimes old batteries still start the engine just fine but they lose their ability to dampen those spikes. The clue is the engine runs better when the generator is disconnected. It can't produce those spikes then.

One thing you might try, if you have access to a battery charger, is run the engine and disconnect the generator when the problem is acting up, then see what happens when you turn the charger on at a low rate. That will produce very high "ripple" which is a variation in the system voltage. You measured 14.3 volts, which is perfect, but the system voltage is actually bouncing rapidly between about 13.0 and 15.0 volts. That variation is what the battery should be smoothing out. The battery charger, by its very nature, puts out much higher ripple than the generator. If the running problem comes back when you turn the charger on, I would suspect the battery first but there's no way to know for sure except by trying a new one. There could also be a computer with a problem with its internal regulator circuit that makes it behave erratically from the voltage variations.

One more thing to look at are the various ground wires. There will be one small ground wire going from the negative battery cable to the body. Also look for any cables or straps between the engine and body that are corroded off.
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Saturday, April 2nd, 2011 AT 6:46 AM
Tiny
VICKIAYALA
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Thanks I will check that out and get back to you.
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Saturday, April 2nd, 2011 AT 7:18 AM
Tiny
VICKIAYALA
  • MEMBER
I ran the truck until it was warmed up and********. I unpluged the alternator and put the battery charger on 2A then 12A charge. The truck ran smooth on both. The volts on the alternator were 14.5 when I pluged it back in while running and 13.5 turned off. I guess I need try to change out the computer then, right?
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Sunday, April 3rd, 2011 AT 2:54 PM
Tiny
CARADIODOC
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We're overlooking something here. It should have run worse on the battery charger than on the generator. Is there any chance a wiring harness has been mispositioned and the magnetic fields from the wires are interfering with some of the engine sensors? Did you see any broken ground straps or wires between the engine and body?
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Sunday, April 3rd, 2011 AT 5:59 PM
Tiny
VICKIAYALA
  • MEMBER
One thing I did fine was when I unpluged the wiring harness to the computer, the #20 pin was broken out and stuck in the harness. I was told to run a ground wire to one of the bolts on the computer box and then use a connector to attach it to the ground wire on the harness. Unfortunately that did not change anything with the problem we are having. I have been trying to fine a computer in a junk yard but they are hard to find. And new they are as you know expensive. After what you just sent me about the battery, do you think I nees to change the battery? Of coarse as you said before, we won't know unless I try with a new one. That's over a hundred for that. God I have spent so much money in the last month, this truck is all I have right now and I have to be able to support my family with it.
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Monday, April 4th, 2011 AT 3:45 AM
Tiny
VICKIAYALA
  • MEMBER
Hey, "GOOD NEWS!" I finally found out the problem and had to share it with you. And also want to thank you for all your help as well. After almost 3 weeks, mechanic after mechanis, part after part, I was given a man, by the name, Bill Lear. He is an electical specialist and he offered to help me. After two days of testing, he came to the conclusion that it was the crankshaft position sensor. I went to the salvage yard and found one. Came home to put it in and when I got to the harmonal balance, there was a small magnet piece that was inside the pulley when I took it off. It was not broken from the the sensor that was on there, but was identical to the center piece. About 7 yrs ago the timing belt was changed by a man in Arizona. All I can think is that he broke the crankshaft sensor then and replaced it, not knowing the broken piece was magnetized to the pulley. So its been riding in there ever since and must have gotten jared lose and was flipping around the sensor making it act eratic like it was. I put everything back together and its running great again. WOW, can you believe it? Thanks again, Vicki
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Wednesday, April 6th, 2011 AT 3:33 AM
Tiny
CARADIODOC
  • EXPERT
Don't think I would have ever figured that one out over a computer. All the knowledge in the world still won't solve every problem. Very happy to hear it's solved. I think Mr. Lear deserves a box of chocolate chip cookies !
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Wednesday, April 6th, 2011 AT 3:58 AM
Tiny
VICKIAYALA
  • MEMBER
Mr. Lear does deserve alot more than that and so do you for sticking in there with me. I so appreciate you trying so hard to help me figure it out. I'm doing some work here to have money to get home on. I can't wait to get there. It's been mentally challenging to say the least for all of us. Thanks again! Vicki
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Thursday, April 7th, 2011 AT 3:22 AM

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