1094 944 porsche cranks but wont fire. fuel pump has no power to it. i changed the ignition. still nothing. could it be the factory alarm.please help.

yes, turning ignition on powers the fuel pump--its electric

Check fuel pump,and fuel pump relay. Alot of newer vehichles have a fail-safe mode that wont let ignition spark, if no fuel pressure is present, or vice versa.

If the passkey system were not working the engine should not crank and the fuel injectors would be dead. The security light would also stay on.
The fuel pump relay gets battery voltage and also voltage from the key switch. The computer grounds the relay to power the pump.
The crank sensor does not come into play until the engine is cranking and it supplies a signal for the ignition and injector pulse.
Are you not getting power from the key switch to the relay, or from the battery side to the relay ?

check for spark, no spark, no fire engine wont run, possible bad ignition coil, wire from coil to distributor cap, no power to ignition coil from ignition switch (rare) wire broken to ignition coil (even rarer)

You injector are plugged,Below the fuel tank is the fuel pump you will need to test this for fuel sitting for ten years the fuel pulsation damper are dried out and you will have to run the fuel pump till the dampner unplugs,turn the key the fuel pump should of been heard if its not electrolyte has already settle in the pump and rendered it useless,you will need a fuel pump

I have Fuel Injected Porsches ... Older & newer than yours...
Both rely heavily on proper FUEL PRESSURE...

... and the factory manuals for both...
HIGHLY RECOMMENDED

I always suggest covering the BASICS first...

Make sure you are getting fuel & fire.

The are simple pressure gauges & spark lights
to accomplish both...

Even if you can hear & feel the injectors clicking...
MEANS absolutely NOTHING without pressure.

1979 PORSCHE 924 2 0L L4 Fuel Pump RockAuto

Check to determine that the fuel pump/relay is working properly by turning on the ignition and listen for the wirl of the fuel pump motor. The pump will turn off after it pressure up, so be quiet and listen carefully.

Start by squirting a little fuel into the throttle body and then crank it and see if it fires up .. if so its a fuel problem if not its going to be something in the electrical. holler if you need more thanks Jerry

You will not be able to hear the fuel pump on that model. First you have to determine if you get fuel and have spark. If it is a fuel problem, replace the DME relay first. Very common. They act up and fail without warning. Part is cheap and located in the fuse box. Next would be the fuel pump.
If it is spark related it may be the Flywheel Reference Sensors. There are two and the cost about $100 each.

Good Luck.