Changing the battery on a 91 BMW K75 S - Fuel Injected. My battery is dead, I'm a weekend mechanic so can't do anything too complex. I tried sliding the storage compartment, toward the rear of

If it fuel injected then you need to change, computer intake manifold, linkage fuel rail out to a line ,Almost easier to buy a new car

Modern luxury cars have very complex computers that require a certain amount of energy to maintain the memory. At autoparts stores they use a device called a memory minder when changing batteries. it is a 9 volt that keeps the computer from resetting when the battery disconnects. I had a friend with a bmw 7 series and he disconnected the battery without a memory minder and the car wouldnt work right. idling low no idrive navigation system, no acceleration, etc. many car computers will relearn the necessary lost data after being started and turned off a few times 4 to 6. I have done this for many cars and it had worked on newer fords, jaguars, bmws, and others.

If your battery is dead enough, even the dead battery indicator won't light. Take the battery to an autoparts store for a bench test/charge first before trying anything else.

Check that the plug didn't fall out of the ECU its located under the seat.
The plug clips on. This same thing happened to me. On the side of the road I figured it out. I just got the bike & the previous owner just replaced the battery. You have to remove the computer aka ECU to change it, The computer controls the spark & fuel injection. There's also a part called the Hall sensor for the ignition, that could have one bad.

I would google and wiki that. not many BMW or Benz mechanics on here, but lots of questions from folks who can afford to buy, but not fix, them. Notably the battery swap gone bad. My mechanical friend has a 2 year old Benz and he had the foresight to hook another battery up in parallel before he pulled and replaced his battery. This kept 12V on the system whilst the battery was out, so his electronics did not take a **** on him which seems to be the typical result of an owner doing this on anything later than a 91 or so. There is a reason why they charge so much at the dealer, even this is not simple on a german car. Expense of having your car towed and fixed from a battery change gone bad could deter you from doing it yourself.

my geo tracker wont turn over the lights wont come on nothing is working iv tested the battrey its fine and checked all the fueses they are fine too why is there no power to any thing?

Main cable from battery has a joint in front footwell check this

this is serious and its beyond the scope of the weekend mechanic to diagnose this problem because of the complexity of the electronics used on the common rail system .Take it back to the garage that fitted the fuel pump under warrenty

sounds like you might have cracked the block

is it injected try new injectors