Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
SYS.OK|MANUAL.DB● LIVE
HOMESERVICE MANUALSJEEP1987COMANCHE LAREDO, 2.5 H, RWD, AUTOMATICREPAIR AND DIAGNOSIS (SINGLE PAGE)ENGINE PERFORMANCETESTING & DIAGNOSISFUEL INJECTION SYSTEM - MULTI-POINTTESTINGSYSTEM TESTINGFUEL SYSTEM TEST
1987 Jeep Comanche Laredo, 2.5 H, RWD, Automatic
Fuel System Test
1987 Jeep Comanche Laredo, 2.5 H, RWD, AutomaticSECTION Fuel System Test
- Remove the cap from the pressure test port located in the fuel rail. See Fig 1 . Connect Fuel Pressure Gauge (J-34730-1) to the pressure fitting.
- Start vehicle. Pressure should be approximately 31 psi (2.1 kg/cm2 ) with the vacuum hose connected to the pressure regulator and 39 psi (2.6 kg/cm2 ) with the vacuum hose removed from the pressure regulator.
- Check the fuel pump flow rate. A good fuel pump will deliver at least one liter of fuel per minute with the fuel return line pinched off. If the fuel pump does not pump adequately, inspect the fuel system for a plugged fuel filter or filter sock.
- Fuel pump flow rate can be checked by connecting one end of an old A/C gauge hose to the fuel test port on the fuel rail and inserting the other end of the hose into a container of at least one liter or more capacity.
- Run the fuel pump by installing a jumper wire into diagnostic connector terminals D1-5 and D1-6. Be sure to pinch off the fuel return line or most of the fuel will be returned to the fuel tank.
RENDER: 1.0x
NO RELATED
Recommended Tools & Savings
Use the Manual With the Right Hardware
Pair factory procedures with proven DIY tools so the instructions are easier to execute.
Affiliate disclosure: We may earn a commission at no extra cost to you.
When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.