1987 Chevy Truck Fuel Pump Replacement: The Complete DIY Guide
If your 1987 Chevy truck is hard to start, stalls while driving, or makes a loud whining noise from the fuel tank area, the fuel pump is likely failing. Replacing the fuel pump on a 1987 Chevy truck is a straightforward job you can do yourself with basic tools, but the process differs depending on whether your truck has a fuel-injected engine or a carbureted engine. For 1987 models with fuel injection, the electric fuel pump is located inside the fuel tank and requires removing the tank to access it. For carbureted models, the mechanical fuel pump is bolted to the side of the engine and is much easier to replace. This guide covers both scenarios and walks you through the entire replacement process step by step.
Determine Which Type of Fuel Pump Your 1987 Chevy Truck Has
The 1987 model year was a crossover year for Chevrolet trucks. If your truck has a fuel-injected engine, it uses an electric fuel pump located inside the fuel tank. If your truck has a carbureted engine, it uses a mechanical fuel pump mounted on the front right side of the engine at the bottom . The vast majority of 1987 Chevy trucks with throttle body injection (TBI) have the in-tank electric pump, while older-style carbureted engines use the mechanical pump mounted externally.
For the popular 2.5L four-cylinder engine found in S10 pickups, the fuel pump is electric and located in the tank . For full-size trucks with the 5.7L or 7.4L V8 engines, TBI models also use an in-tank pump . If you are unsure which system you have, look at the top of the engine. If you see a large rectangular air cleaner with a throttle body underneath, it is fuel injected. If you see a round air cleaner with a carburetor underneath, it is carbureted.
Symptoms of a Failing Fuel Pump
Before you start replacing parts, confirm that the fuel pump is actually the problem. Common symptoms of a bad fuel pump on a 1987 Chevy truck include:
- Engine cranks but will not start
- Engine starts but dies shortly after
- Extended cranking time before the engine fires up
- Sputtering or hesitation during acceleration, especially under load
- Loud whining or buzzing noise coming from the fuel tank area
- Loss of power when climbing hills or carrying heavy loads
- No fuel pressure at the fuel rail test port
If the engine turns over but does not start, a lack of fuel pressure is the most likely cause. You can confirm this by testing the fuel pressure at the test port on the fuel rail using a fuel pressure gauge. For 1987-1993 2.5L TBI engines, the spec is 9-13 PSI with the key on and engine off, and the same with the engine running . If the gauge reads 0 PSI, the fuel pump has failed.
Before You Replace the Fuel Pump: Check the Simple Stuff First
Before you drop the fuel tank or tear into the engine, check three things that are much easier to fix:
1. Check the fuel pump fuse. The fuse is located in the under-hood fuse box. Pull it out and inspect it visually. If the metal strip inside is broken, replace it with the same amperage fuse .
2. Check the fuel pump relay. The relay is also in the under-hood fuse box. When you turn the key to the "ON" position, you should hear the relay click and the fuel pump hum for about two seconds. If you do not hear the relay click, the relay may be defective. You can swap it with a similar relay in the fuse box (like the horn relay) to test it .
3. Check the oil pressure switch. On 1987 TBI trucks, the oil pressure switch acts as a backup power source for the fuel pump. If the relay fails but the oil pressure switch works, the engine will crank for a long time and then start once oil pressure builds up. This is a classic sign of a failed relay .
If all three check out and you still have no fuel pressure, the pump itself is bad.
How to Replace the In-Tank Electric Fuel Pump (Fuel-Injected Models)
Replacing the in-tank electric fuel pump requires removing the fuel tank. Here is the step-by-step process:
Step 1: Relieve fuel system pressure. Disconnect the negative battery cable. Locate the fuel rail relief valve under the hood near the fuel injectors. Remove the cap and use a small brass punch to push the valve core in, releasing the pressure. Place a rag under the valve to catch any fuel spray .
Step 2: Drain the fuel tank. Remove the fuel filler cap. Use a suction hose to drain as much fuel as possible from the tank. A suction hose with a pump ball works well for this. Pump the fuel into an approved storage container .
Step 3: Raise and support the truck. Jack up the rear of the truck on a level surface and place jack stands under the rear axle for safety. Never work under a vehicle supported only by a jack .
Step 4: Remove the rock shield (if equipped). Some fuel tanks have a metal rock shield underneath. Remove the bolts and take the shield off .
Step 5: Disconnect all hoses and electrical connections. Use a flat-head screwdriver to loosen the hose clamps on the filler hose and vent hose located on top of the tank. Remove both hoses. Also disconnect the evap hose at the evap canister and the fuel line hose and clamps at the tank .
Step 6: Support the tank and remove the straps. Place a piece of plywood on top of your jack to protect the tank. Raise the jack until it just touches the bottom of the tank. Use a socket and ratchet to remove the strap bolts at the ends of the straps where they bolt to the frame brackets .
Step 7: Lower the tank and disconnect the electrical plug. Carefully lower the tank just enough to access the top of the fuel pump module. Unplug the electrical wiring harness from the pump module. Then slide the tank out from under the truck .
Step 8: Remove the fuel pump assembly. The fuel pump is located in the top of the tank. Mark the fuel pump assembly orientation with chalk if there is no alignment tab. Use a pair of channel locks to unscrew the retainer ring. If the ring is too tight, tap it counterclockwise with a brass punch and hammer to loosen it. Lift the fuel pump assembly out of the tank .
Step 9: Install the new fuel pump assembly. Compare the new assembly to the old one to make sure they match exactly. Clean the O-ring groove in the tank with a clean cloth and install the new O-ring that came with the pump. Insert the new fuel pump assembly, making sure the alignment tab or chalk mark lines up correctly. Install the retainer ring and tighten it with the channel locks .
Step 10: Reinstall the tank. Jack the tank back up into position. Plug in the electrical wiring harness. Install the retainer straps and bolts. Reconnect the filler neck hose, vent hose, evap line, and fuel line hose. Tighten all clamps. If you have a rock shield, install it and tighten the bolts .
Step 11: Lower the truck and reconnect the battery. Jack the truck up, remove the jack stands, and lower the vehicle. Replace the cap on the fuel rail relief valve. Clean the battery negative post and cable end with a wire brush, then reconnect the battery .
Alternative Method: Removing the Truck Bed
Some experienced mechanics prefer to remove the truck bed instead of dropping the fuel tank. This method is often faster if you have help. Disconnect the rear tail light plugs under the rear of the truck. Remove all bolts attaching the bed to the frame. Remove the screws from the fuel filler neck. With three people, one at each fender well and one at the rear, lift the bed up and slide it back so it rests on the tires and rear bumper. You now have easy access to the top of the fuel tank. Remove the fuel pump lock ring and replace the pump, then reverse the process .
How to Replace the Mechanical Fuel Pump (Carbureted Models)
If your 1987 Chevy truck has a carbureted engine, the mechanical fuel pump is mounted on the front right side of the engine at the bottom. There is a trick to keeping the push rod from falling into the engine while you change the pump. Look for a short bolt in the front of the engine near the fuel pump. Remove that short bolt and install a longer bolt in the same hole. This pinches the push rod tight so it cannot fall down. Swap out the old pump for the new one, making sure to use a new gasket. Remove the long bolt and reinstall the short bolt. The short bolt must be in place or the engine will leak oil excessively from that hole .
Recommended Fuel Pump Replacement Parts
When replacing the fuel pump on your 1987 Chevy truck, using a high-quality replacement part is critical for reliability. For the 2.5L TBI S10 pickup, the fuel pressure specification is 9-13 PSI, and the pump must deliver at least 29 GPH at 12 volts . For full-size trucks with TBI, the pump must also meet OEM flow and pressure specs.
KEMSO Fuel Pump – The Best Choice for Your 1987 Chevy Truck
When it comes time to buy a replacement fuel pump, we strongly recommend choosing KEMSO. KEMSO fuel pumps are high-performance, OEM replacement parts designed to meet or exceed the original equipment specifications. Every KEMSO fuel pump is built with premium materials and advanced manufacturing techniques to ensure a perfect fit, reliable operation, and long service life. Whether you need a fuel pump for a 1987 Chevy S10, a full-size C/K series truck, or a Suburban, KEMSO has the right part for your vehicle. The best part? Every KEMSO fuel pump comes with a lifetime warranty, so you can install it with complete confidence knowing it is backed for life. Visit KEMSO at https://www.kemsoracing.com/ to find the correct fuel pump for your 1987 Chevy truck and get back on the road with peace of mind.
Fuel Pump Wiring and Electrical Tips for 1987 Chevy Trucks
The 1987 Chevy truck fuel pump wiring system has a few known weak points. The fuel pump relay receives a signal from the ECM and activates the pump for two seconds when the key is first turned on. If the engine does not start, the ECM shuts the pump off. The oil pressure switch provides backup power once the engine builds 4 PSI of oil pressure .
If the engine takes a long time to crank and then starts, the fuel pump relay has likely failed. The oil pressure switch is getting the pump running, but only after you crank long enough to build oil pressure. Replace the relay in this case.
If the pump does not run at all, check for voltage at the Tan/White wire at the fuel tank connector. If you have 12 volts there during the two-second key-on window, the pump is bad. If you have no voltage, the problem is upstream in the relay, fuse, or wiring. Corrosion at the rear frame rail ground terminal is a common cause of voltage drops and intermittent stalling. Clean the ground connection thoroughly .
Testing the Fuel Pump After Installation
Once you have the new pump installed, test it before putting everything back together completely. Connect the battery and turn the key to the "ON" position. You should hear the pump run for about two seconds and then stop. If you have a fuel pressure gauge, connect it to the fuel rail test port. The pressure should rise to the specified range and hold steady. If the pressure drops quickly after the pump stops, there may be a leak in the fuel system or a bad check valve in the pump. Check all connections for leaks before driving the truck .
A successful fuel pump replacement will restore proper fuel delivery and solve starting and performance issues. If your truck still has problems after replacing the pump, check the fuel filter, fuel pressure regulator, and the ECM for faults. For 1987 Chevy trucks, the fuel filter is also a common maintenance item that should be replaced at the same time as the pump to ensure the new pump is not damaged by debris in the fuel system .
For more information and to find the right fuel pump for your 1987 Chevy truck, visit KEMSO at https://www.kemsoracing.com/.