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    1996 5.7 / Intermittent loses power-Bogs down. Died twice at StopLight. Starts right up and runs fine mostly

    That's good to know. I hadn't had any problems with my '94 so the problem wasn't with the '07 at all but with the battery. It would stall, stutter, etc. even while driving.
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    1996 5.7 / Intermittent loses power-Bogs down. Died twice at StopLight. Starts right up and runs fine mostly

    I just bought another truck after crashing my previous '94 Sierra. It's a 2007 Sierra with only 108K miles on a 4.3L engine. It's a completely different truck from what you have but the symptoms are amazing close to what you are reporting. My '94 had an OBD I system so reading the codes didn't...
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    Heated o2 conversion wiring

    You know about "assume" correct? Especially on wiring.
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    Coolant questions

    IMO, the 180F thermostat is too cold. It will run OK but its going to cost you in gasoline. I did a chart on the coolant temperatures some time ago. It's posted below. The thing to keep in mind is that water boils at 212F but you won't be running only water since the water is diluted with...
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    Can’t seem to get all air out of rad

    You could have a leak between manifold water port and the exterior of the engine. I had that problem once and the water/coolant never showed up on the driveway. The leak was above the water pump where the manifold had a leak to the outside of the head but there was a catchment cast into the top...
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    P0441 Code

    Considering the age of the vehicle it most likely is a bad Evap Purge valve. This may cover it: https://www.700r4transmissionhq.com/p0441-chevy-suburban/
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    ‘92 5.7 tbi stalls after tach goes crazy

    Check your cable connections to the battery. Disconnect and clean them. Also the wire that goes to the alternator. If you see any corrosion at the battery terminals, cut the insulation parallel to the wire and peal it back a bit to see if the corrosion has crept into the cable. If so, replace...
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    No crank/heatsoak issue

    I had the same problem but it turned out to be the starter solenoid
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    5W30 or 10W30, synthetic or traditional? Opinions wanted

    The advice I got from a mechanic friend was to use the same type of oil that was used to break in the engine, i.e. synthetic or conventional and once you hit 120K miles use the high mileage oil in a weight that suits your normal environment temperature wise. So I use conventional 10W40 in...
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    AC Compressor

    Your low pressure side sensor is probably failing to have enough pressure. There is a switch, typically on the accumulator, that will open so the clutch does not engage and tear the compressor up when the pressure in the system is too low. If that's the case, you won't be able to measure any...
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    Buy a Single Spark plug wire?

    For future problems: save the bad plug wire and throw it on the ground under the truck. I own some rural property and run into this problem occasionally. The problem is that the rat will grab it and run off with it from time to time. That's why I save the entire old set when I change them now...
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    Wanting to buy a GMT400, how old is too old, and years to avoid? (discussion)

    I have a '94 I bought new off the lot. It's a 4.3L V6 Fleet truck with 250,000 miles on it. No razzle dazzle, just a plain Jane truck. 4.3L engine, 4L60e transmission, GU6 - 3.42:1 differential, AC, Radio. The down side is it is getting old and even the junk yards only hold them for so long so...
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    Which Harmonic Balancer?

    "So there's this possibility--maybe even a probability--that the "vibration" you're feeling is the engine not running right, rather than a failed damper." That got me thinking of a problem I had many, many years ago with the coil on a Pontiac. Once I started looking from that perspective I...
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    Which Harmonic Balancer?

    Wouldn't that set a code and/or give me a CEL?
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    Which Harmonic Balancer?

    No, I did not unbolt the converter. I just checked that the mount was present and tight. I had the trasmission rebuilt back in 2004 or 2005 but I haven't had any problems with it so far. Of course that was 17 years ago so I guess that could be it. I've got the harmonic balancer ordered. I think...
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    Which Harmonic Balancer?

    I took a cab to my Dr appointment just to be safe. After I got back I found that I could get my fingers between the back of the balancer and the front of the timing chain cover to feel around. I found the raised area as shown under the yellow rectangle, so I've ordered the part. I'm not at all...
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    Which Harmonic Balancer?

    I determined the problem was the balancer by eliminating everything else. It vibrates whether the truck is moving or sitting still once it heats up. That rules out the steering parts, wheel balancing, ujoints, and suspension parts. I checked all of the mounting points like motor and transmission...
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    Which Harmonic Balancer?

    I've developed a vibration in the steering wheel of my 1994 GMC C1500 4.3L V6 LB4 that I have determined to be the harmonic balancer. When I start it in the morning and the engine is cold there is no vibration at all. But when I get it up to operating temperature there is a fairly strong...
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    TRUCK IS ACTING CRAZY

    Here is a link to a site that tells you how to read codes at home: https://mechanicbase.com/trouble-code/obd1-codes/ Scroll down to "How to Read OBD1 Codes at Home" That page also has a list of codes and their meanings.
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    94 GMC 4.6L vibration

    All good ideas for diagnostics but I didn't find any definite problems. Harmonic balancer checks out with timing light. My gas mileage is as good as when it was new: 13-15 in town and higher 17's to lower 18's on the highway so I doubt there is any missing. I changed out the plugs, plug wires...
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    94 GMC 4.6L vibration

    You're correct. It is 4.3L. It's OBDI so I'm not sure I'll get misfire counts. I'll do the timing light in the morning.
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    94 GMC 4.6L vibration

    I'm starting to feel a vibration in the steering wheel. It has 250K miles on it. The vibration is slow at idle in the driveway and speeds up as I pull out and drive it. I drove it @ 80MPH for 2 hours today and of course the vibration was gone at speed but it came back at idle. I'm thinking...
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    4.3 tbi has a drinking problem..

    Replace your coolant temperature sensor (CTS). It's the one on the intake manifold in the front of the engine near the radiator hose attachment point. It's only about $12 so that's a quick and cheap fix, if that is the problem.
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    Does anyone know what this is ? Truck is shutting off randomly.

    I have a 94 GMC Sierra C1500 4.3L that I was driving about 65 MPH on I-10 in San Antonio when it died in the same way- it just shut down like someone turned the key off. My problem was the fuel pump. I rolled it into a mechanic's shop, they replaced the fuel pump, and it fired right up after that.
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    TBI issues

    We need more info: Year Make Model Engine Transmission

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