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Light Flare


Twister

Well-Known Member
V8 Engine Swap
Joined
Mar 4, 2010
Messages
1,921
City
Omaha, Ne
Vehicle Year
1985 1987
Transmission
Manual
Ok, so i have an 85 B2, when ever i give the truck some gas the light will flare and get brighter. It does it every time i push the gas weather the truck was just started or has been running for a half an hour.

I have replaced the battery, battery cables, battery terminals, voltage regulator, starter solenoid and i put in a 60 amp alternator.

What else could it be :icon_confused:

Any input is appreciated :icon_thumby:
 
Sounds like the alternator isn't spinning fast enough at idle.

Are you running an undersized crank pulley?
Has the alt. been "rebuilt" for higher amperage than stock?
Is the engine idle speed correct?
 
Sounds like the alternator isn't spinning fast enough at idle.

Are you running an undersized crank pulley?
Has the alt. been "rebuilt" for higher amperage than stock?
Is the engine idle speed correct?

1. I would have no idea if i am running an undersized crank pulley, as far as i know the engine is stock.

2. I dont think it has been, i bought it remaned from Napa about 5 months ago.

3. Yes the engine is sitting at the correct idle as stated on the sticker under the hood.
 
i'm going to guess a bad alternator... i've seen them be bad out of the box, exp reman's...

fwiw, my bike, fitty and mustang all do it
 
i'm going to guess a bad alternator... i've seen them be bad out of the box, exp reman's...

fwiw, my bike, fitty and mustang all do it

Hmmm, its the only vehicle i have ever driven that does it.
 
my ranger even does it just a little... especially when i've got all the electronics on... headlights, heater, interior light, stereo, auxilary lights, and the idle is low for whatever reason...
 
Mine does it with nothing on. Will a higher amperage alternator help?
 
Not specifically... It's not amperage, it's just that your alternator isn't turning fast enough at idle...
 
Not specifically... It's not amperage, it's just that your alternator isn't turning fast enough at idle...

So how do i get it to turn faster at idle when the idle is spot on? :icon_confused:
 
Your alternator might be dead... But an overdrive pulley would help
 
I would also agree, bad or poorly-functioning alt.

Alternators that are rewound for higher amps typically do poorly at idle speed, but (supposedly) put out more current at high RPM (I say 'supposedly' because mine didn't seem to do any better at high RPMs than the stock OE one, but then didn't do JS at an idle).

It finally blew up so I got a rebuilt one from a local rebuilder (not a mass-remanned one like you get at Napa/Autozone, etc.) and the voltage doesn't sag at an idle anymore unless I got both the headlights on and the blower fan on max.
 
^^ typically you will see a sag with that much on, so it's normal... but it shouldn't be much



(directed at OP)
 
Well i guess i will go and get my alt tested on Monday and report back with the results.
 

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