96 Suburban won't start, unless...

[plnestel]

First time here. I have a 96 Suburban 1500 - 5.7L - 2wd with 139,000 miles and it won't start. At first it was a long crank to start engine. Now it cranks but will not start. But if I pour some gas into the throttle body it will start. Once started it runs fine. Fuel pressure was good 40-60 psi. Thanks for your help.

[Firminator]

Originally Posted by plnestel

First time here. I have a 96 Suburban 1500 - 5.7L - 2wd with 139,000 miles and it won't start. At first it was a long crank to start engine. Now it cranks but will not start. But if I pour some gas into the throttle body it will start. Once started it runs fine. Fuel pressure was good 40-60 psi. Thanks for your help.

Sorry I don't have the cure however here's some info. Although I'm experiencing a very similar symptom, there may be too much difference in our rides because mine is an 86 Suburban. To start it in the AM I have to pump the gas pedal several times, or it will just crank without starting. Sometimes, even after pumping the pedal, it will start, run a few seconds then die out. Sounds like it's staved for fuel. I pump the pedal a few more times, it starts again and almost always keeps running after that. Once I start it in the AM, it easily re-starts all day, until it sits without running overnight or longer. I've been doing this for many years because it hasn't been enough of a hassle to start tearing into finding the cause. I suspect that somewhere in the fuel system there is a slow leak that allows fuel to back flow so that it is not readily available to the carburetor (and/or fuel pump) and that pumping the accelerator "primes" the system. Once primed, fuel is readily available until the slow leak "un-primes" it. All of this is just a theory because the pain of the problem hasn't justified the time and effort of looking for the solution. Hope this helps at least a little.

[Fedexjetmx]

HelloFirst you said once you get it running it was fine? Correct? And basically you had to manually feed it gas to get it to run. With the key off open the door or have someone go the back of the truck, the instant you turn the key to the "On" position (you don't have to try to start it). You should hear a very distinct buzz sound only momentarily....about 2 to 5 seconds. If no sound, do what you did before to get it started. Once running go back to the back this time listen for a continuous buzzing. If you hear it than your "start" relay is not working.Under the hood (I cant remember which side) there is a roughly 6"X6" black box that should say fuses and relays, remove the lid hopefully these is a diagram inside the lid if so look for a "fuel pump" and or a "Start fuel pump" relay. That is your culprit.

[superchuckles]

actually, i've just had this same problem. i just bought the truck, and i couldn't get it to start cold, just like you're saying - turns out, someone had just replaced the coolant temp sensor (tells the computer the engine coolant temp) with a coolant temp switch (for vehicles with electric fans). since both sensors look totally identical, the only way i knew it was bad, was to check by plugging in my laptop early in the morning when it had never been started -- it read 78 degrees celcius, when my tranny temp sensor was reading 22 degrees celcius. changed the sensor out (then both read the same) and it has started perfectly ever since. a malfunctioning sensor is likely the problem in yours, and they're only about $9 just about everywhere. if they want $15 or more, that is the TEMP SWITCH one, and will not work (the computer will think the engine is already warmed up so it will be too lean and not start) if your idle isn't going crazy, you need to replace the temp sensor. if your idle is going all over the place, it's the IAC motor.