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post #1 of (permalink) Old 05-22-2003, 11:18 AM
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4.3 acting up

i just bought a 86 blazer wit a 4.3 from my parents for 200 bucks.it has been sittin for about a year.i did a tune up on it and thought it was fine.well about 5 min after running it cuts off and wont start up.thought it was the fuel pump so changed that.same problem.now i think it may be the coil beside the distibutor an [img]images/graemlins/cussing.gif[/img]d ive been told it could be a clogged cat.it has 160.000 miles on it.im not the greatest mechanic and havent worked on a 4.3 very much and in need of some help.so does any1 know or have a idea,thanks
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post #2 of (permalink) Old 05-22-2003, 07:36 PM
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Re: 4.3 acting up

an 86 with a 4.3? 88 was the first year for them, unless this one was a carbed unit swapped in from an old Astro van. When it does run, is it running smoothly? or is it rough? did you check the fuel filter at all? what about the injector nozzles? are they spraying a constant fine mist, or is it a sort of drippy? are the plugs, wires, distributor (be it HEI or point) components in good shape? lotsa questions to answer. 'nother idea is to get your hands on a Haynes or Chilton Manual.
post #3 of (permalink) Old 05-22-2003, 09:20 PM
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Re: 4.3 acting up

sorry forgot 2 mention the 4.3 was swapped in from a wrecked 89 we use to have.checked the distibutor,changed the little black thing underneath the top of distibutor,changed cap and rotor,new plugs and fuel filter.then the fuel pump.
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post #4 of (permalink) Old 05-23-2003, 08:57 PM
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Re: 4.3 acting up

That could be it right there. Unless you made some mods for the wiring harness (the 4.3s use an HEI system for ignition. lots of computerized stuff) you're not gonna get much functioning from the engine. Good news is, you CAN get the parts to make it a Carbed engine, just check out some of the leading engine performance manufacturers and retailers.
post #5 of (permalink) Old 06-06-2003, 12:59 AM
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Re: 4.3 acting up

The most common answer that someone will offer up in your time of need is a "clogged cat"... Loose Translation: "I DON'T UNDERSTAND THE TRUE OPERATION AND FUNCTION OF AN INTERNAL COMBUSTION ENGINE, OR ITS EMISSIONS CONTROL COMPONENTS, but... I KNEW A GUY WHOSE BROTHER'S NEXT DOOR NEIGHBOR'S AUNT'S COUSIN'S BUCTHER'S HAIRDRESSER HAD THE EXACT SAME PROBLEM (even though it was an Asian car that had all the Autozone engine-mod goodies that were available, and actually burned up the engine and exhaust while drag racing a soccer-mom's bone-stock Cavalier that her delinquent son "borrowed" for the night to race down the local dark, dippy, and just-a-little-bit-unsafe road)." [img]images/graemlins/confused.gif[/img] People just like saying Catalytic Converter, because they think it sounds cool...

Chilton's Service Manuals will give you just about all the info you'll ever need to complete your own repairs, and you can usually come up with a more accurate diagnosis if you dig in and work at it yourself.

A Catalytic converter hardly ever fails, especially on a Chevy. The typical GM Truck Cat is not a honeycomb type... it has ceramic balls in chambers that the exhaust gases pass through. Pollutants are broken down and modified or consumed, for the most part, by the Cat, hence the Catalytic effect, and the creation of water that drips from the tailpipe. A failed Cat will usually be caused by: 1. Low quality fuel, 2. Continuous use of improper (low) octane level fuel, 3. Fuel system malfunction, which will cause a runs-lean or runs-rich condition, or 4. An excessive oil consumption or internal oil leak concern, where the oil will accumulate in the Cat, causing exhaust overheat and Cat meltdown.
An easy test for the Cat: Does water drip from your (a person's) exhaust? If so, then the Catalyst Emissions system is functioning the way it was designed and is most likely ok...

Now, to your truck... Is the truck out of fuel, or is the fuel old (both common with vehicles that have been sitting)?
You have what is called the "Triangle of Combustion", and at each point of the traingle is a vital component of the proper function of an engine, based on the fact that it's mechanically sound. At the points, you have fuel, air, and spark.
If the engine didn't make any funky or loud noises just before it quit running, you are probably safe in assuming that no mechanical failure has occured. From that point, dive in and check for spark @ the coil, check for fuel that should be clean and strong-smelling, and properly delivered to the TBI unit. Air delivery is simple... is the air intake blocked off, or did a bird get sucked into the TBI unit? [img]images/graemlins/smile.gif[/img]

You'll find that the 4.3 is a very good engine, and can produce more horsepower in a bone-stock normally-aspirated pickup than the new supercharged Nissan v-6 pickup can.
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