I have a 95 Silverado with a 5.0
vortec.replaced fuel pump,fuel filter,n spider
injectors.will not crank..will run fine if you
pour gas in the intake.theres fuel to the
spiders and voltage to the spiders but will
not run...whats my problem
check for a good ground for the pump , I think that's where the sending unit is , it should prime the system when you hit the key in the run position (key on/engine off), you should hear it, it's faint but listen , it should run then shut off
Please clarify your description...you stated that it will not "crank" but will run fine if you pour gas into the intake, which is odd because it generally won't run if it will not crank. So, is it a "crank but no start" situation or is it a "no crank" situation? It's an important difference. I will assume you have a crank but no start problem. As a 1995, you (and I) have an intermediate production design, meaning some were OBD1 designs, and some were OBD2 designs, and some apparently were an OBD1 design with an OBD2 connector. 94 and earlier were all OBD1, and 96 and later were all OBD2. This only matters if you want to scan the data stream, which is helpful during troubleshooting. With that said, all computerised cars basically do the same thing at startup. With the key on, but engine off (i.e. not in the "start" position), the fuel pump should activate for about 2 seconds to prime and pressurize the fuel system. If you roll the key straight to the start position, it still performs this prime function while trying to start. It also does this to provide fuel pressure REGARDLESS of the oil pressure. Now, if during startup, the computer (ECM or PCM) detects an adverse condition that could cause damage to the drivetrain, it will inhibit the signal that activates the "fuel pump relay", and subsequently, the "fuel pump". Side note* Most people think the fuel pump is activated directly from the computer. Not the case! It can't handle the necessary current needed to drive the pump. With "that" said, several of the conditions that would cause the fuel pump signal to be inhibited are "low oil pressure" and "wide open throttle". The latter is vastly more important than the first, and so, the computer will not provide fuel to an engine it thinks is set to redline, and then grenade your engine. Now, the throttle position is just a sensation provided to the computer so that it can adjust various things like a/f ratio, ignition timing, shift points, etc... The TBI "mechanically" acts like a carburetor regardless of the status of the throttle position sensor (TPS), meaning that when you put fuel or spray ether into the throttle body, it will generally start if it gets a spark and the oil pressure rises. If it starts and runs at this point, your "Oil Pressure Sensor" is fine and your "TPS" is suspect. If it starts and runs for a few seconds, and then shuts off, your "Oil Pressure Sensor" is suspect. Chances are your vehicle is showing many other indicators besides the "No start" condition such as: 1) Hard transmission engagement 2) Hard shifting 3) No 2-3 shifting 4) Poor overall performance 5) Poor acceleration. My vehicle had all of these problems. The most important one to me was 3) No 2-3 shifting. This is a limp mode function, but, continued use will burn out your transmission. The failure to start (without ether) "and" shift is what indicated to me that it was a faulty TPS. I hope this helps. Philip
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