1973 280se 4.5 turns but don't start

[randysue2]

HELLO EVERYONE... MY CAR IS TURNING BUT NOT STARTING, ANY IDEAS TO WHY, I GOT NEW FUEL PUMP, FUEL FILTER. IT SEEMS TO COUGH AND SPIT AND BACKFIRE. I CHANGED A COUPLE OF FUEL INJECTORS I KNOW YOU SHOULD CHANGE THEM ALL. WOULD THAT KEEP IT FROM STARTING. ANY HELP ONCE AGAIN WOULD BE GREATLY APPRECIATED RANDY.

[bwostosh]

Pull the wire out of the center of the distributor cap,
Set it near a ground source,
have someone crank the motor and look/listen for sparking zap,zap,zap.

or get a test light probe, or a voltmeter or....

there are step by step procedures to diagnose the problem.
do not hack at the problem.

or just set your wallet on a competent, experienced with this D-jetronic system, mechanics' table and hope it won't vanish completely.

[Tomguy]

What spurred the fuel pump and injector replacement? The proper D-Jet pump is a fairly high volume pump and if you have the wrong type it may cause your issues (The right kind is several hundred $$ so if you paid under $200 it's almost surely the wrong one).

Spitting, sputtering & backfiring can be a fuel or a timing issue. It sounds like you are getting spark so this is the realm where you need a timing light first, to verify timing, then you can move on to testing injector firing and fuel pump volume (1 liter in 15 seconds IIRC, but search the forums just to make sure).