97BMW Z31.9 ran fine ,battery went dead ,replaced, engine cranks, no fire to plugs ,no power to fuel pump. checked fuses,relays,jump pump terminals pump will run.

NEW RELAY MIGHT FIX IT

Engine cranking, did you check for spark at the plugs, also, check fuel injector pulse. Any applicable trouble codes?
When you first turn on the key, no crank, can you hear the pump run for a couple seconds?
If only a fuel issue, jump the relay to see if pump will run. Unplug relay, use jumper wire between terminals 30 and 87, the pump should run, don't need to use your key. As you can see, terminal 30 is hot all the time. Also, check that fuse.
Let us know what you find?

check your crankshaft position sensor. fuel+spark+compression+timing=ignition.

The oil pressure sensor only keeps the pump running after the vehicle is started. If you turn key to on, the computer should signal to the fuel pump relay, turning the pump on for a couple of seconds to pressurize the fuel system. Then the computer signal stops. When the key is turned to start-cranking the engine- the computer again energizes the fuel pump relay, keeping the pump running until the engine starts.
If you have a voltmeter or test light, pull the relay out and check the relay terminals. One should be hot at all times-the power feed for the pump. The computer signal will be on the coil side of the relay-will have power for 2 or 3 seconds after key is turned to on. Or it will have a constant signal when the engine is cranking. If you can find both hot terminals at the relay, then start looking for a bad wire from relay to pump, or a bad ground for the pump, or a bad ground for the relay's coil side. Post back if unclear or other questions. When you pull the relay out, the diagram for it will be on the side of the relay-telling you which is the power feed and the terminal to the pump, and the coil side of relay, both the coil power side and the coil ground terminal.

No, there would not be another fuse. How did you jump the pump, at the pump relay, or at the gas tank? I would want to know if the power feed for the pump is present at the relay. If you jumped it there, the feed is good. If you pull the relay out, one terminal for the relay should be hot at all times. Two terminals should be hot when cranking the engine over- the power feed for pump, and the signal from computer to the relay's coil side. If you have both signals, check for a pump ground problem.
If a security light is on, the pump or injector circuit may be immobilized.

Check the power feed for the pump at the fuel pump relay. Pull the relay out, and with a test light clipped to a ground, probe all the terminals that the relay plugs in to. One terminal should be hot at all times. If no terminal has power, either a fusible link off the battery has failed or a maxi fuse has blown-check a wiring diagram to see how the relay gets power to it.
If the relay has power to it, check the other relay terminals with the engine cranking. When cranking the engine, two terminals should have power-the fuel pump feed, and the signal from computer to activate the relay. If both signals are present, check the pump wire from relay to tank, check the fuel pump ground, and check if the coil side of relay has a good ground-signal from computer goes to coil input side, the coil output terminal should go to ground.
Good luck. Post back with what you find.

MIGHT BE A RELAY ! LOCATED UNDER HOOD, YOU SHOULD SEE RELAY BOX NEXT TO BATTERY. MAKE SURE BATTERY TERMINALS ARE CLEANED, PUT SOME VASOLINE ON TERMINALS, RECONNECT, TIGHTEN. CHECK ALL GROUND WIRES. ARELAY BOX MAY ALSO BE LOCATED NEXT TO POWER STEERING . COULD HAVE A FAULTY SOLONOID@ STARTER, IGNITION SWITCH COULD ALSO BE FAULTY, ITS NEVER EASY TO PINPOINT ELECTRICAL PROBLEMS, PROCESS OF ALIMINATION, CHECK ALL STARTING CIRCUIT SYSTEMS, IS YOUR SHIFT LEVER ALL THE WAY IN PARK ? DOES ENGINE CRANK ? OR DEAD, NO POWER ? ARE YOU GETTING SPARK ? HOW ABOUT FUEL ? DID YOU REPLACE BOTH THE AIR &FUEL FILTERS ? THE STARTER / SOLONOID IS WHAT CRANKS THE ENGINE, I THINK YOUR PROBLEM IS THERE ! REPLACE RELAY TO STARTING SYSTEM, ARE YOUR SPARK PLUG WIRES NEW ! THEY WILL SHORT OUT ANY SPARK IF OLD, DIRTY, I SUGGEST A TUNEUP, NEW FILTERS, AND REPLACE STARTER/SOLONOID !!!!!!

Sounds like you spent a small fortune on fuel pumps. Don't keep trying to jump it to start. Take the battery off and have it charged up. No further tests will be valid without a fully charged battery.
Is it the computer? Always a possibility, but that should be your l;ast resort. You might change it and later find out it was a bad fuel pump relay, or something like that.
Lets go back to the point you put gas in and it fired off. ( Further cranking after that may have run the battery low enough that you lost spark.) A mechanic would next check if power was getting to the pump by checking the pump wire for power at the tank connector, when the engine was cranking over. If no power, pull fuel pump relay and check for available power on one terminal where relay plugs in. If power is ar the relay, swap relays and see if was a bad relay. If no help, further electrical tests need done before condemning the computer, wiring needs checked, grounds need checked, and the relay itself has one terminal that goes to ground. You be better off diagnosing the problem, or having it done, rather than throwing new parts at it. Try to get the pump working first, then if still won't start, check the injectors and injector circuit. And go back to check for spark-at this point having removed and replaced what you have, and jumping it, and cranking, cranking, cranking-if no spark, start by checking all fuses on the car.


Not much help, I know, but proper testing is the only way to find it.. Or just go ahead and change everything till you find it or are broke. Not being snippy, if I can help anymore, post back.

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fuel pump relay

These cars are known for having engine related electrical problems that can be difficult to track down. One dead sensor is sufficient to prevent start up .

It is possible that your problem had nothing to do with the jump start or battery replacement.

Without a full diagnosis anyone not able to test the vehicle will be guessing.

One thing I would do is to check your fuse panels for all engine related fuses such as fuel pump, ignition and fuel injection to ensure these fuses are sound.
Check all visible wiring carefully including your battery connections. Carefully disconnect and then re-connect the battery at both terminals.

Your best option is to have the car towed to a reputable repairer that is familiar with these cars so he can run a full check and isolate the problem.

Whether you have blown something in the course of jump starting the car is unknown.

In future, when jump starting these older vehicles always turn the headlights on and do not turn them off again whilst the vehicle is running until after the spare battery used for the jump start has been fully disconnected. Everything else should be off.