1. Check the Fuel Pump Relay:
* Location: Find your owner's manual or an online resource (like a forum dedicated to S10s) to locate the fuel pump relay. It's often under the hood in the fuse box or under the dash.
* Testing: The easiest test is to swap the fuel pump relay with a relay of the same amperage rating from a different circuit (e.g., a working horn relay – but only if it's the same amperage rating; otherwise you risk damaging components). If the problem goes away, you've found the faulty relay. If not, move to the next step.
2. Check the Fuel Pump Inertia Switch:
* Location: This safety device is usually located under the dash or in the engine compartment. It's designed to cut power to the fuel pump in a collision.
* Testing: Look for a small red button on the switch. Press it. If it pops back out, it's likely working. If it stays in, it needs to be reset (it should pop back out after being pushed). If it's broken, replace it.
3. Check the Fuel Pump Fuse:
* Location: The fuse box is usually located under the hood or under the dash. Consult your owner's manual to locate the fuse for the fuel pump.
* Testing: Visually inspect the fuse. If it's blown (the wire inside is broken), replace it with a fuse of the same amperage rating.
4. Check for Power at the Fuel Pump:
* Access: You'll need to access the fuel pump. This usually requires dropping the fuel tank (a more involved process) or accessing it through the bed of the truck, depending on the model. Caution: Work in a well-ventilated area and disconnect the battery's negative terminal before working near fuel lines.
* Testing: Use a test light or multimeter to check for power at the fuel pump's connector. You should have power when the ignition is turned on (but not necessarily when cranking). No power indicates a problem in the wiring, relay, or ignition system.
5. Check the Fuel Pump:
* Testing: If you have power at the pump but it still isn't running, the pump itself is likely faulty and needs to be replaced. This requires removing the fuel pump, which is generally a more complex job involving dropping the fuel tank.
6. Consider Other Factors:
* Low Fuel: Make sure you actually have fuel in the tank!
* Clogged Fuel Filter: A clogged filter will restrict fuel flow, making it seem like the pump isn't working. It's relatively inexpensive to replace, so it's worth checking.
* Fuel Pressure Regulator: This component regulates fuel pressure. A faulty regulator can prevent sufficient fuel from reaching the engine. Testing requires a fuel pressure gauge.
Important Notes:
* Safety First: Working with fuel systems involves potential fire hazards. Always work in a well-ventilated area, disconnect the battery negative terminal, and avoid sparks.
* Consult a Repair Manual: A repair manual specific to your 1986 Chevy S10 2.5L will provide detailed diagrams and instructions. This will save you time and frustration.
* Professional Help: If you are not comfortable working on your fuel system, it's best to take your truck to a qualified mechanic.
By following this systematic approach, you should be able to pinpoint the cause of the fuel pump issue. Remember to replace parts with the correct specifications for your vehicle.
