1992 Chevy Truck 1500 running BAD!
arkansas girl
16 years ago
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timwilliamsbiz
8 years agojohnandapril6969
8 years agoRelated Discussions
99 Chevy Blazer hard starting when cold
Comments (11)Isn't this kind of work fun? The only time you can measure and test for the problem is while it's happening. Any other time that the car actually starts, everything you test will be "spot on" as you put it. Which is a reference to the most likely suspect for your mothers car's symptom. Low fuel pressure I.E. a bad pump. These things will not start with 54PSI of fuel pressure, they must achieve 56PSI! Your gage has to be accurate within 1PSI in that range to actually see this occuring. The thing is, hitting this with a little ether (I prefer propane) will give it some fuel to burn and increase manifold vacuum, and often times allows the car to start, because the vacuum actually helps open the poppet injectors. The poppet injectors are why this thing needs a minimum of 56PSI to start. Other things to consider. "Spark volume" I know you replaced secondary ignition, did you clean the breathers in the base of the distributor? They tend to clog, and then crankcase gasses will collect in the distributor causing corrosion, and then the spark will short to ground inside the distributor. Fuel: It takes more than just fuel pressure to ensure the engine is getting fuel. The injector must be triggered on by the PCM. I have had the two wire connector between the engine harness and the injector corrode and cause a loss of injector command. Plus you need to have a good crank signal trigger to not only tell the computer to drive the injector, but to command the module to trigger the coil. Tell me, when the car acts up. Key on, you hear the pump run for two seconds. Start cranking the engine, do you hear the pump turn back on? This would tell me if the PCM sees the signal from the crank sensor....See More1992 Chevy 1500 no injector pulse
Comments (3)When a shop posts a help request similar to what is above, the normal reply is to tell them to substitute a known good technician. VBG... Test this and change that is not how to diagnose and repair a problem like this, well, by now you probably realize that because it simply doesn't work. Now sure there are times that this method does work, and occasionally you don't even spend a fortune doing it. But as a pro, you'd fail so often you would not last as a technician. A "noid" light is not an accurate test of the systems ability to turn the injectors on. The injectors initially start to draw current at such a level that if they were allowed to stay turned on long enough they would each draw twenty amps+ of current. To prevent overheating the injectors the computer uses what is called a peak and hold system. How it works is one transistor (also referred to as a "driver") turns on and starts to open the injector. Once a sufficient current flow is reached, a second transistor turns on that has a resistor in series with it, the first transistor turns off and that limits the current flow to around 1.8 amps. The "peak" part of the voltage waveform causes the injector to open, and the hold portion allows the injector to remain open long enough to dispense the right amount of fuel. A noid light will flash with as little as 1ma, or .001 amps. This type of testing has tricked just about everyone who relies on it at least once. The right way is to measure the current flow with a low amps probe an an oscilloscope. You can also use the scope to monitor the ground side of the injector to watch for both drivers signatures, and their inductive kick on turn off which is an indicator of the strength of the magnetic field that was created when the computer turned the injector on. Now just because current is flowing that does not mean that the injectors physically opened, nor does having fuel pressure guarantee there is fuel at the injectors under sufficient pressure to be injected into the engine. There are screens on the injectors themselves that serve as a last defense filters, as well as there is usually an inlet screen to the throttle body just inside of the fuel inlet nut. Once you prove that electrically the injectors should be opening, by measuring the current flow with them connected, and/or measuring their inductive kick. Plus you re-confirm that there is fuel pressure, AND volume. Then you have proven that problem is inside the throttle body, and you will need to take it apart to find out what is going on....See MoreTrading in the SUV or truck?
Comments (9)I think the purpose of moving to a more efficient car is more than simply the cost. Unfortunately, China is dealing with shortages of gas because of requirements vs. availability. I think the more gas guzzling SUVs we get off the road the better it is for all of us as our future may not increase gas consumption at 10% annually (or whatever the stats). However, I do not see this happening until our politicians force or tax these big vehicles for destroying our roads, killing more other drivers in accidents, and taking 10 minutes as a gas station. If the $1500 is worth it - get a used Jetta TDI (maybe a year or two) before their prices start going up. I would LOVE to buy a Passat Diesel but waiting for a 6 spd manual version....See MoreGM (Chevy Colorado '05) Passlock
Comments (10)Thanks again john_g, and I enjoyed reading an old post of yours on the same subject, concerning a S-10, the model replaced by the Colorado. In any case, careful reading of the owner's manual (I usually read for speed rather than content and miss all the important stuff). From what I read I see the Passlock intervention is limited to the fuel system, disables the fuel injector(s) if there is an attempt to start the vehicle without a "proper" key in the ignition tumbler. So, why the symptom no starter crank untell the release of the key? Also, it seems the latest symptom of cranking but the engine dies as soon as the starter releases is consistent with the fuel being cut off. Looks most like a tumbler problem, i.e., a legitimate key is not recognized/registered by the tumbler (or associated electronics - I also tried a back-up key with the same result). It seems possible too that a defective tumbler could intermittently not make the contact to engage the starter until the key is released - the fact that the starter then disengages when the engine starts is a still a mystery. Guess I'll have to take it to the expert, and the Dealer seems to charge $150 and hour, so the price will be in the hundreds. Not a feel-good for Chevy in my book. My last previous Chevy was a 1969. Maybe I'll wait another 40 years before I buy another... oh, yes, I and perhaps GM will not be around in 40 years....See MoreBarry Nelson
8 years agoBarry Nelson
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