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.
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HOMESERVICE MANUALSPLYMOUTH1994LASER RS TURBO, AWD, AUTOMATICREPAIR AND DIAGNOSISENGINE PERFORMANCESYSTEMENGINE CONTROLS - BASIC TESTINGFUEL SYSTEMFUEL PRESSURECHECKING FUEL PRESSURE
1994 Plymouth Laser RS Turbo, AWD, Automatic
Checking Fuel Pressure
1994 Plymouth Laser RS Turbo, AWD, AutomaticSECTION Checking Fuel Pressure
- Relieve fuel pressure. On 2.0L, remove throttle body bracket. On all models, wrap fuel line with shop towel and disconnect high pressure fuel line at fuel rail. Install Adapters (MD998709 and MD998742) between fuel rail and high pressure fuel line. Connect fuel pump pressure gauge.
- Connect negative battery cable. To activate fuel pump, apply battery voltage to check terminal. See Fig 1 . Check for fuel leaks. Disconnect battery voltage from check terminal. Start engine and let idle.
- Measure fuel pressure with fuel pressure regulator vacuum hose disconnected and plugged. Also measure fuel pressure with fuel pressure regulator vacuum hose connected. See FUEL PRESSURE SPECIFICATIONS table.
- Increase engine speed to 2500-3000 RPM 2-3 times. Ensure fuel pressure does not drop when engine returns to idle. Check for fuel pressure in fuel return hose by gently pinching hose (with hand) while raising engine speed. There will not be any fuel pressure in return hose if fuel volume is low.
- If fuel pressure is too low, check for clogged fuel filter, faulty fuel pump or regulator. If fuel pressure is too high, check for bent or clogged fuel return hose or faulty fuel pressure regulator.
- If fuel pressure is identical with fuel pressure regulator vacuum hose connected or disconnected, check for clogged or broken fuel pressure regulator vacuum hose or faulty fuel pressure regulator. If fuel pressure is within specification, go to next step. See FUEL PRESSURE SPECIFICATIONS table.
- Stop engine and check for change in fuel pressure. Fuel pressure should not drop. If fuel pressure drops slowly after engine is stopped, replace fuel injector. If fuel pressure drops immediately after engine is stopped, replace fuel pump.WARNING: When disconnecting fuel pressure gauge, cover hose connection with towel to prevent fuel splash, caused by residual pressure in fuel line.
- When fuel pressure check is completed, remove fuel pressure gauge and adapters. Install NEW "O" ring on end of high pressure fuel line. Connect high pressure fuel line to fuel rail. On 2.0L, install throttle body bracket. On all models, check for fuel leaks.
FUEL PRESSURE SPECIFICATIONS
| Application | psi (kg/cm2 ) | ||
|---|---|---|---|
| 1.8L & 2.0L Non-Turbo | |||
| W/ Vacuum Hose Connected | 38 (2.7) | ||
| W/ Vacuum Hose Disconnected | 47-50 (3.3-3.5) | ||
| 2.0L Turbo | |||
| Auto. Trans. | |||
| W/ Vacuum Hose Connected | 33 (2.3) | ||
| W/ Vacuum Hose Disconnected | 41-46 (2.9-3.2) | ||
| Man. Trans. | |||
| W/ Vacuum Hose Connected | 27 (1.9) | ||
| W/ Vacuum Hose Disconnected | 36-38 (2.5-2.7) | ||
RENDER: 1.0x
NO RELATED
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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.