The automatic transmission of my GMC S15 will not engage in DRIVE unless I tap the gas pedal. Is this normal?
This is not how the GMC S15's automatic transmission should operate, and you must check the system for any problems. In your case, your truck's transmission might be an issue of slipping, which is caused by an internal mechanical failure or low level of transmission fluid. The easiest cause to confirm would be the transmission fluid since all you have to do is check the ground under where your vehicle was parked for any red or brownish fluid puddles. However, if you don't find any leaks, then the only possible cause left is internal transmission damage. Aside from your truck not engaging in drive, the powertrain control module (PCM) usually sets a diagnostic code that translates to "gear ratio error." Also, when you remove the transmission oil pan, you will most likely find sediment, which is the material that has fallen off the friction discs in the transmission. Once confirming that your system indeed has internal damage, you will have to do a transmission overhaul.
I was driving my GMC S15 when the truck just suddenly died. What's wrong with my truck and how do I fix it?
When the GMC S15 stalls like how it happened to your truck, it is often related to ignition problems and happens when the engine loses spark. A faulty crankshaft position sensor, a failing ignition coil, or a bad ignition switch that intermittently loses contact could cause this. To troubleshoot this problem, you must check for spark. You can do this by pulling off a plug wire and placing the end near the block while someone else cranks the engine. Be careful not to hold the wire while your companion is cranking as it may shock you if the ignition system is working. If you do not see a spark or hear the plug wire snapping while the engine is cranking, then the ignition system is the problem and needs to be repaired.
When I turn the key on my GMC S15, fuel leaks out of the throttle body. What's causing this to happen?
While your main suspect could be the throttle body itself, you must first check for other possible problem components. Check the injector O-ring seals, as they might be the source of the leak. Unplug the injector wire connector then try turning the key to ignition again and observe if fuel is still leaking out of the throttle body. If the leaking has stopped, then the O-ring seals are the problem. Otherwise, you have to move on to the ignition module, which might be defective. A bad ignition module would falsely send a very fast pulse on the wire connected to the PCM even without the engine cranking. Check for loose or corroded electrical connections from the ignition module. Clean oxidized terminals and replace any broken wires you find. You should also use a light timing tester to check the output of the module. If the light blinks, then the module is good. If both the O-ring seals and the ignition modules are good, then you must get the throttle body looked at.