Question about 1989 GMC Suburban

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Cobbed up alternator

Just bought 89 Suburban. Alt. went bad, and this is when I discovered the alt was actually TWO alts combined. The engine is a 350 vortec, with 4brrl carb. so looks like the cobbing isn't limited to the alt. The alt is running on a "V" belt, and the fan/water pump off serpentine belt. What must be done to correct the problem with the cobbed alt? Is there anyway to determine what year the engine is? Obviously this is a crate engine. Pretty sure the Sub didn't come from factory with this engine. please don't respond with technical questions questions as you are dealing with a 62 yr old female whose mechanical knowledge is limited and what little I do know is based on google research.
Thnx
MCApodca

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  • MaryCannon Apodaca
    MaryCannon Apodaca Feb 08, 2009

    Could someone please tell me what types of engines came were factory for the 1989 Chevy Suburban? The mechanic I asked to rebuild the carburetor on my Sub told me that an "89" shouldn't have a carb.
    He was too busy when I called to set up an appointment to discuss this with me. I have no doubt (he was a Chevy dealership mechanic for 18 years before opening his own shop) that he will figure out the whole mess, but in the mean time I am very curious.


  • MaryCannon Apodaca
    MaryCannon Apodaca Feb 09, 2009

    Thnx much for the info. The engine is a 350 vortec, or so it appears. Do you know if the vortec was being installed factory at that time?
    Mechanic is A Chevy man for many years, so I am sure he knows what he is doing. Guess I am fearing a major repair bill thinking that much will have to be changed on this cobbed up mess. I will definitely check out those numbers. The more I know about my vehicle the more comfortable I am on the road. I would like to be able to be half way intelligent about what I am driving in the event of future breakdown. Thnx again for your response.
    MCApodaca


  • MaryCannon Apodaca
    MaryCannon Apodaca Feb 10, 2009

    From what I am gathering, the carb wasn't original equipment, so that makes me wonder how many more things the previous owner modified to keep this old gal on the road. The engine sounds good.. smooth and quiet. No strain on it on highway at higher speeds. I owned a 72 half ton with a 350 and so am very familiar with what one can expect performance wise from this engine. Being old school.. The 283 was my most favored V-8 I'll get back to you all with the mechanics discoveries and solutions. Thnx again for your assistance.

    MCApodaca


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Your michanic is right, mid 80's is when they went from carberator to throuttle body, for them to put the carb. on this engine they must have by pass the computer, i have done this myself before, it would take to long to explane the whole procedure. But if you want to know what the original motor was it could have been either a 305 cu. in. or a 350 cu. in. if you take the vin.# and go to general motors web site you might be able to find out, as i have done this on the classic cars that i own. There is also an id.tag on firewall by break booster with #'s you may be able to use to track down info.

Posted on Feb 09, 2009

  • ccn7 Feb 09, 2009

    To my knowledge the vortec engines started around late 95 early 96, i have a 95 half ton pickup and i believe its the last year for that motor before they switched to the vortec, witch all in all is a better engine. There is a reason why they put a carberator on it instead of the throttle body, your michanic can explane that to you better than i can, as it would take forever for me to explane.

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1 Answer

1999 3.2l. Why are battery and brake lights on?


was not on before the new alt,? is alt new or used.?
or came on only after the new ALT?????????
my guess, is 2 failures.! (one ignored and 2nd grew)
on with engine running, guess yes.
Good question and is same answer on all cars.
1: engine rpm too low, what is yours (below 80 rpm)
2: fan belt slips. bad tension pulley (weak and old???)
3: Alt bad, or its wires bad.
4: brake level low, (@MC) or hand brake switch stuck on, or other brake failures. a plenty, scan the PCM and ABS if you have ABS.
id not drive it with the brake lamp on (Savvy?)
the battery light is really the ALT charge lamp.
it glows anytime the Charge system can not charge the battery
if you drive far like that, the engine will stall and not crank.

5: the horn fuse power the alternator, so check the horn fuse
10amp , key on, 12vdc on both sides of fuse is needed/
fyi: the meter fuse runs the charge lamp, if said lamp is dead bingo.
6: fact 2, the PCM does NOT run the Alternator on the 3.2L .
7: alternator case not grounded right.
8: battery is bad, causing alternator to drop off line
9: battery cables bad, at the 4ends or they are bad.
10: the plug on the rear of alt is bad or its wires or pins rusty.


brakes:
the brake lamp has 3 inputs ("OR" logic) master cylinder level low.
the hand brake lever and the EBCM (electronic brake control module)
a technician unplugs each to see what causes the error.
if you unplug mC wire and hand brake wire
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stock car YJ ? , or all hacked up. (old cars get hacked)
2.5 or 4.0 liter engine? still have a real jeep alternator not upgraded?

loss of electrical power (first rule, we never need to guess.!!!)
not with a voltmeter. (tool that costs $20 )
alternator good (by what means, autozoned?) ( we can find out one car)
but low on gauge. what gauge in dash voltmeter.? sure...
i think you car has no charge lamp only the dash VM.

own an volt meter? a DMM? hand volt meter?

1: if the alternator charge lamp is stuck on driving.
2: is battery voltage at 13.3 to 15vdc with engine at 800 RPM idling
alternator belt not slipping, for sure.....???
if the battery voltage is near 12.5v and falling running that is
an Alternator system failure, note i said, system. !!!

this is first. if we get to here. we can find the real cause.
test 3:
is the charge lamp on keyon, and goes out running?
make sure the big fuse for the alternator in the engine bay fuse
box is not blown, 50amp?

I have no 95 FSM and my online source sucks for 95

Alternator dead: (alt good)
1: belt slipping . engine at 300rpm, nah.
2: fuse blown, the big one. (engine bay fuse box)
3: ;wrong alternator, there are many, most others will fail, even good ones.......
4: alternator ground bad. (end to end, to battery minus)
5: bad wiring to same. bad connections, any to battery or alt.
6: some jeeps the PCM has the field regulator, see link below.
ECU pin 20 , is field pin, it is on 95, 4.0L (engine not stated)

is the CEL lamp on, and throwing code 41 DTC?, alt, field errors?

the alt has 4 pins, battery, field,ground and voltage sense.
The reg is in the PCM. and if bad is a bad $3 transistor..
see same form for fix for that issue..

i think this is same as your. 1996 is big change year.
http://www.jeepforum.com/forum/f12/1993-wrangler-pcm-ecu-ecm-pin-out-diagram-1170004/


you can test the alt, PCM wire pulled !, by full fielding the alt.
grounding the field term, no wires on field pin of alt.
see FSM for details on that.
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ran cheery, the exhaust ran red hot? LOL.
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the alt charge lamp glows, did it?

old post,
bad alt, or battery is no good.
try a known good battery , and make sure the
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fix that FIRST !
This is really simple in most cases.
it's a system, called a charge system.
it has 3 /4 parts.
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if the engine RPM is 400 , the Alternator will give UP.
so first engine RPM 800 then i strobe the alt pulley, oops belt slips, mine runs at 1.8 ratio or 1400 rpm at alt pulley.
for a DIY is the belt tight?
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The system now is ALT wires and battery. 3 things.
if the ALT is good and the battery is good (tested)
then it must be what. the wires.
The alt can put out 50+ amps..
there are at least 4 wires on most alts and any can fail.
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alum and steel (iron) both corroded, add salt and its worses
in 2 ways corrosion and electrolysis. (google that)
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that rear connector.
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and guess what, each brand of ALT uses different parts here.
EVEN REBUILTS, so best practice, is to assume the lamp
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no lie , testing the alt, in car is hard.
many times the ALt just shuts down. (faults)
and with zero current flow, you can not find the voltage drop
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there is a method but is risky , on car, called "full fielding"
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one other crazy failure
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at alldata dot com.

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