REPLACING FUEL PRESSURE REGULATOR A) BMW 630 i: The injection pressure¹) is set to 2.5 ± 0.2 bar (35 ± 3 psi) through vacuum by the pressure regulator regardless of load conditions. Check by connecting a pressure gage between cold start valve and line. Up to 1980 Models: Disconnect plug on air flow sensor and bridge 36 and 39 in plug. Turn on ignition. ¹) Fuel return causes injection pressure to go beyond specifications. This will cause starting difficulties. Return line is clamped or filter screen in intake is clogged.  * See Specifications
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From 1980 Models: Pull off plug (1) on double relay. Bridge contact 8 (88d) of pump relay socket and B +. Fuel pump runs. |  |
Clamp fuel return hose slowly and let pressure increase by about 4 bar (60 psi). Replace pressure regulator, if pressure drops below 2.5 ± 0.2 bar (35 ± 3 psi) when releasing fuel return hose. Detach intake pipe of cylinder no. 4. Installation: Cut off old gasket. Cut off piece of new gasket to match removed piece. |  |
Disconnect pressure regulator at line. Disconnect fuel return line. Disconnect vacuum hose at collector and remove pressure regulator. |  |
B) BMW 633 i: Check fuel pump delivery pressure 13 31 029.¹) Pull off vacuum hose (1). Detach fuel hose (2) and coupling (3). ¹) Fuel return causes injection pressure to go beyond specifications. This will cause starting difficulties. Return line is clamped or filter screen in intake is clogged. 13 31 029 * See Specifications
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Unscrew mounting nut (4) and remove pressure regulator. |  |
Vehicles after change point in 1982 REMOVING AND INSTALLING FUEL PRESSURE REGULATOR Disconnect air hose (1) and fuel hose (2). |  |
Unscrew bolts (1). Remove fuel pressure regulator. |  |
Installation: Check seal (1), replacing if necessary. |  |
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Checking: Install pressure tester 13 3 060 with connecting hose and t-adapter 13 3 064 in the fuel feed line - in front of fuel pressure regulator. |  |
Pull off fuel pump relay (1). Bridge terminals 87 and 30 with Special Tool 61 3 050. Check fuel injection pressue*. * See Specifications and Nominal Value Microfiche
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