is this an Alternator problem on my Isuzu?

Hi there, here's my situtation, not too long ago i noticed that when i would start my 1992 isuzu pickup it would stall a second after i started it, then
on the second attempt it would stay lit, but on my dash with all the gauges most of the lights would be lit-up, my heater and fan would not work as well and the washer blades were ultra slow, after giving the truck a really good REV to 3600rpm it would kick out of this mode and run completely normal, as i loked into this problem i looked under the hood and took a volt meter to the battery when the truck was turned off....to my surprise it was a normal 12.9V....i checked a few other area for voltage on the engine and same 12.9V appeared (including the Alt.) my next test was to start the engine and voltmeter it again, after starting the engine...there was no change in Voltage...the same 12.9V.....that is until i gave the engine a good REV again.....then it kicked the Voltage up to 14.3V in its normal state.....i had the Alternator re-built since i thought maybe it was an issue with the diode-trio in the rectifier....$150 later i find the Truck is still doing the same thing. Has anyone have input on this issue? i'm getting to the point of pulling my hair....the funny thing is i have another 1990 isuzu pickup thats doing the exact same thing but started awhile earlier...maybe i can kill 2 birds wiht one stone?!
Appreciate your time folks.
Thanks
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Is it fuel injected?
Steve
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yes, its a 2.6 4 cyl. fuel injected.

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This ones easy, it is the voltage regulator which is part of the alternator. Effectively the alternator is not electrically connected to the electrics untils the engine is running and the alternator is generating a high enough voltage. When you rev it the voltage goes up the alternaters regulator connects it to the electric, your measure the voltage go up and all the dash lights go out. My wifes 3.1TD trooper does this fairly often. No big problem, but it may be time to get a recon alternator

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ruez46 wrote:

Both my Diesel Isuzu's do this. Even after replacing alternators or regulaters. I think I just belongs that way. Doesn't gave any problems. Just the nature of the car. Kind regards, Erik-Jan.
--

http://www.fotograaf.com/trooper

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My 1988 Impulse did something very similar last week. Several indicators including battery condition lit up (I should say they stayed lit after startup) The blower motor, compressor and vent controls were all inoperative. When I selected the highest blower speed I heard loud relay chattering from under the hood. If I turned the blower speed to "Off" all lights and noise would go out.
It turned out to be the "X2" RELAY as shown in the manual. It was stuck in the released position. As I understand it, the vehicle has things that are useable with the key on, yet other things that are only supposed to work when the engine is running. This relay seems to be what re-routes power between these modes based on output from the alternator driving this relay's coil exclusively. It was stuck in the "engine not running" position.
A very alarming symptom set-I as most people would have absolutely had a cow if I didn't have a general feel for how some stuff works.
Another way to describe it is from history: " We have a Bus B undervolt, multiple caution and warnings and a loud noise associated with the caution and warnings"
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