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.
1991 Mercedes Benz 350SDFACTORY OEM SERVICE PROCEDURE
Fuel Pump
NOTE:
Fuel pump performance is a measurement of fuel pressure and volume availability, not regulated fuel pressure.
FUEL PUMP PERFORMANCE
| Application | psi (kg/cm2 ) | Min. Vol. In 30 Sec.: Pts. (L) |
|---|---|---|
| 4-Cylinder | N/A | N/A |
| 6-Cylinder | 77-80 (5.4-5.6) | 2.1 (1) |
| V8 | 90-93 (6.3-6.5) | 2.1 (1) |
REGULATED FUEL PRESSURE
| Application | (1) psi (kg/cm2 ) | (2) psi (kg/cm2 ) | ||||
|---|---|---|---|---|---|---|
| 4-Cylinder | N/A | N/A | ||||
| 6-Cylinder (103 Engine Series) | 70-73 (4.9-5.1) | 41 (2.9) | ||||
| V8 | 83-86 (5.8-6.0) | 41 (2.9) | ||||
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DIESEL FUEL PUMP TIMING (1)
| Application | Degrees ATDC | ||
|---|---|---|---|
| 5 & 6 Cylinder | 14.5 | ||
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DIESEL INJECTOR NOZZLE PRESSURES
| Application | psi (kg/cm2 ) |
|---|---|
| 5 & 6 Cylinder Opening Pressure | 1957.5-2102.5 (137.6-147.8) |
Factory Service Tools
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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.