The last few days have been very cold (around zero) and when trying to start the car it turns over fine, but will not start. It fires occasionally, but after a few times fires even less. I pushed it in a heated garage, and let it sit 12 hours. Still same problem, After turning over several times, have no gas smell so I am assuming a fuel problem. 1/2 tank of gas, and has run fine until now. Thinking it is a fuel issue, Could it have been frozen, and now a relay or fuse for the pump is blown? Where is the fuel pump? Is there a fuel filter that may be clogged? If so where? Any HELP will be appreciated !
Fuel pump is in the fuel tank.filter is either under the car on frame rail or under the hood.fuse and or relays will be under dash or under the hood.
SOURCE: BMW 525i will not start
There are six fuse panels for an E39 BMW
Fuses
F1 - F45, fuse panel 1, glove compartment. Twist white plastic
retainers 90 degrees and pull down from top of glove compartment.
Fuse 31 (10 amp) protects fuel pump relay(K96)
Fuses
F46 - F6, fuse panel 2, trunk located behind right side luggage compartment interior panel.
Fuse 54 (15 amp) protects fuel pump relay(K96)
Before I would do any of the following, I would check the above fuses and put a bottle of HEET into the fuel tank. Fuel filter changing is not hard, but it will take you about an hour.
The fuel pump is another story (BMW has a special spanner wrench(16 1 020) to remove and install the threaded collar.
E39 BMW use a two-lobed fuel tank(think saddle bag like). Each with its own fuel level sending unit that has a float connected to a variable resistance wiper contact. To equalize fuel level between the two tank lobes, a siphon pump is installed in the left lobe. The resistances need to be approximately the same. The fuel pump is on the right lobe under the tank sending unit beneath the threaded collar at the top of the fuel tank which is accessed by removing the rear seat cushion. WARNING When removing the fuel level sender or the fuel pump, the fuel tank should be drained to 1/4 capacity or below. The fuel in the fuel line is under pressure (45-75 psi). Always unscrew the fuel tank cap to release pressure in the tank before working on the tank or lines. Disconnect battery negative cable.
The fuel filter is located beneath the center of the car near the driver's seat usually under a protective metal cover held on by small screws. Not hard to replace but car will need to be on jack stands and 1/4 tank or less of fuel in the tank. Definitely wear safety goggles or face shield as the fuel will come out on face. Have a fuel catch pan under the filter. Clamp the fuel line before and after the fuel filter(long metal cylinder) before loosening hose clamps. Loosen center clamping bracket and hose clamps on either end of filter. [Some have an inline fuel pressure regulator.(Remove vacuum hose, pull out locking clip, remove fuel pressure regulator).]
Drain fuel from inlet side of filter and check fuel for rust moisture or other contaminats.
Installation is reverse. When installing fuel filter, ensure fuel flow direction arrow points to front. Should have at least 5 liters of fuel in tank before restarting. The fuel pump will be damaged if run without fuel.
PT Stanley
SOURCE: Bmw 1991 525i heating problem while driving 10 to
hi 7785ds, I would take a look at the thermostat first. Your vehicle is equipped with a mechanical thermostat and it can stick open, or the retaining fingers break, allowing full flow all the time. I would recommend r&i the thermostat before condeming something else. Please post your findings if the thermostat checks ok, and I will be glad to assist you further.
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same as above - replaced the MAF but still floods when trying to cold start
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