92 S-10 Blazer ??Engine Problem??

[Drive24]

Just bought a 1992 S-10 Blazer 4.3L a couple weeks ago. When I bough it the guy said that it needed to have the timing adjusted.. But after talking to a friend he said that on the engine it automatically adjusts itself. But after driving it awhile I began to wonder if it was something else. here is what it does.............
I crank it over....it starts....idles a bit high but it idles.....put it in drive and go....and it goes.....after about 5 miles......it begins to lose power.......if I pull over and shut it off and restart after no longer than a minute.....it starts.....put it back in gear...just like there is nothing wrong.....until another five miles(if that)---------
SO THEN KINDA STARTED TESTING IT SO SEE IF I COULD PIN POINT WHATS CAUSING IT..........
STARTED IT ONE DAY......IT GOT WARMED UP UNTIL ATLEAST THE THERMOSTAT OPENED.....THEN THE IDLE BECAME IRREGULAR(IT WOULD GO UP AND DOWN & ONCE IN AWHILE IT WOULD DIE)......ANY SUGGESTIONS......
THERE IS NEW PLUGS, WIRES, CAP AND ROTOR, AIR FILTER, AND THERMOSTAT IN IT.
I WAS THINKING POSSIBLY IT NEEDED A NEW FUEL PUMP BUT I DON'T KNOW ENOUGH TO MAKE THAT DIAGNOSIS.
AND ALSO THE OIL PRESSURE GAUGE GOES ALL THE WAY UP WHEN THE ENGINE IS STARTED(ABOVE 80) AND I AM PRETTY SURE IT WORKS CAUSE WHEN THE ENGINE'S IDLE GOES UP AND DOWN IT GOES WITH IT. ANY SUGGESTIONS WOULD BE REALLY GOOD CAUSE I WOULD REALLY LIKE TO GET IT GOING.

[old_master]

Is the Service Engine Soon light on? If so, what are the codes?

Ignition timing: Under the dash, on the passenger side, behind the carpet, taped to the firewall, is a single tan wire with a black connector. Unplug the connector and check/adjust the ignition timing. After it's adjusted properly, plug the connector back together.


Runs poor after a few minutes: When the engine is first started, the ECM controls the engine in what is called "open loop" operation. During this time it ignores the oxygen sensor voltage and uses a pre-determined air/fuel mixture and base ignition timing. After the engine warms up, the ECM goes into what is called "closed loop" operation and begins watching the oxygen sensors and adjusting air/fuel mixture and ignition timing.

Bring the engine to operating temperature, check/adjust ignition timing, then bring idle speed to approximately 1500 RPM and check oxygen sensor voltage at the sensor(s). It should fluctuate roughly between .2VDC and .9VDC. Post your results.

[Drive24]

the check engine lights is not on. and i was reading on it and alot of things were saying that it can not be adjusted. whats your take on that? what would i need to adjust it if I could? i will definitly check the O2 sensor though, never though of that.

[old_master]

1992 4.3L could be Throttle Body Injection, (TBI) or Central Multiport Fuel Injection, (CMFI), sometimes referred to as "CPI". Both engines used the EST system and the wire under the dash has to be disconnected to adjust ignition timing. What is the 8th character in the Vehicle Identification Number, (VIN)?

[Drive24]

The 8th charactor of the vin is "w"

[old_master]

92 "W" engine is a vortec, CMFI system. Disconnect the EST connector and check/adjust ignition timing. Check oxygen sensor voltage with the engine at operating temperature and holding the idle speed steady around 1500 RPM. Fuel pressure and leakdown are critical on the CMFI engines. If you don't have a fuel pressure tester, it would be a worthwhile investment. Harbor Freight has them for around $14. Post back if you need help with the fuel pressure and leakdown tests.

[Drive24]

been trying to find the fuel line going into the engine to hook the pressure tester up at and i can't find it anywhere. If you could tell me where it is that would be great. A picture would be even better if you had one. I cant find anything on the internet that shows me.

[blazee]

Pop the hood, from the driver's side of the vehicle, look toward the rear of the engine, locate the distributor/distributor cap/plug wires, from that point follow the plug wires toward you about 3-4 inches, and then look below them. It's right there on the fuel line going into the intake. It should have a black screw-on cap on it and look very similar to an oversized tire valve. Your fuel pressure tester connects to that valve.

[old_master]

[iroc343]

You may want to investigate a partially blocked catalytic converter before you go much further. The symptoms sound more like that than timing problems.

[old_master]

Originally Posted by iroc343

You may want to investigate a partially blocked catalytic converter before you go much further. The symptoms sound more like that than timing problems.

Good thought, however, Drive24 says it clears up after restarting. The ECM reverts back to open loop operation after a restart. A restriction in the exhaust system wouldn't be affected by a restart.

[iroc343]

You're probably right Old Master, that's why I thought maybe it was partially blocked, and shutting it off for a minute or so relieves enough backpressure to let it run good for another 5 miles before acting up again.

[Drive24]

was wondering if i could get step by step instructions to time it. I just really do not want to screw this up as this is my first timing.

[old_master]

Originally Posted by Drive24

was wondering if i could get step by step instructions to time it. I just really do not want to screw this up as this is my first timing.

See post #2.

[Drive24]

I ended up just taking it in and having them adjust the timing. the mechanic said it was behind 12 degrees. also said the ball joints were getting bad. he never told me if it was the upper or lower but not to worried about at the moment. would rather have it running good before i do anything like that. it definitly idles better now though. but it still cuts out after awhile. if i feather the gas while i am drive it will still keep some momentum but when a hill comes along it sputters and loses power. Fuel pump? fuel filter? i got a filter for it but the lines going in and out of it are rusty as hell i dont want to snap them trying to twist the nut off of the filter.