How to repair an alternator for a 1994 bmw 740i?

This should help you out......https://www.2carpros.com/diagrams/bmw/740i/1995

Have you run the fault codes first as it may not be the fuel pump. Find out what is faulty before you spend good money on what is not faulty.

How about tune up,wire,coils,fuel filter.

I believe you will have an issue with your injectors. Check your mileage with the manufacturers recommendation on replacement.
Before you do anything, just put into your fuel tank a SLICK 50 Fuel Treatment Additive - half tank of petrol - and take it for a good drive. Read the directions on the box. Probably solve the problem for the time.

Yes. There are several diodes in the alternator that prevent the current from reversing. If a diode is defective, the battery could drain through the alternator windings.

Hi.

If it does turn over and electrical works, then the problem is unlikely the battery. You can try jump starting. If it cranks when jump-starting it may be a weak battery, starter motor or alternator, but I don't think that this is the problem.

Check if there is spark on all cylinders. Do a code scanning (this car is OBD1, you will need to do the scan at the dealer place or to find a BMW OBD1 tool- Universal OBD2 scanner will not work on a 1994 BMW). If the codes return misfire or mixture related errors check fuel pressure, check sensors and parts that determine the mixture (MAF/MAP, AIT, O2 sensors, IAC and EGR system), check the vacuum system for leaks and check the crank sensor.

Regards.

Ginko

Could just be a loose sensor wire, or a bad sensor. Can't say if it's expensive or not.

http://www.bmwtips.com/tipsntricks/Exhaust/O2sensor.htm

pump suckin up garbage from the tank settlement from all the moisture or bad gas gel up the pump outlet line cause this problem.

I have a 740i bmw it starts but acts like the fuel filter is cloged