No spark

[dr.john]

i recently replaced the engine bay wiring in my 1982 928. there are 12 volts to the coil. when i turn the key to start, the engine turns over and the negative side of the coil pulsates as if it is being triggered. a half second later the coils loses its spark. i'm baffled as to what it is. i tried another coil but it has the exact same result. any help and/or advice would be appreciated.

[stepson]

Check your ballast resistors mounted on the passenger side of the engine bay near the front.

[Dmitry at Pelican Parts]

Originally Posted by dr.john

i recently replaced the engine bay wiring in my 1982 928. there are 12 volts to the coil. when i turn the key to start, the engine turns over and the negative side of the coil pulsates as if it is being triggered. a half second later the coils loses its spark. i'm baffled as to what it is. i tried another coil but it has the exact same result. any help and/or advice would be appreciated.

Hello and welcome to the forum! In addition to what the above member suggested, check out the link below to a previous thread about this. There are likely more out there, just use the Search function in the above bar. Hope this helps out out a bit.

Suddenly no spark...

[dr.john]

new green wire solved spark issue. engine started, but quit after a few seconds. FP is working. has fuel up to fuel rails. sprayed choke cleaner down plenum for 30 sec and engine ran for 30 sec. stopped spraying and engine quit. odd things- after engine would quit, it would restart for a few seconds and quit. try again and same thing. try again and wont start. let it sit for five minutes and it starts for a few seconds and quits. 2nd- as soon as you touch the gas pedal at idle it quits.when running with choke cleaner, as soon as you touch pedal it backfires. any help is appreciated.

[honerboys]

definitely sounds like a fuel issue - injectors not firing? - you can pull the injector rail on one side and place each injector in a container to catch fuel and try cranking to look for fuel from injectors - disconnect center coil wire so there's no sparks at plugs first - have fire extinguisher ready..just in case - it might be starting on the cold start injector and the main ones aren't working so it dies after a few seconds

[stepson]

Relay, Relay, Relay.

Install your new fuel injection relay in XVI (fourth from the right on the top) with a 928 615 119 0

[dr.john]

so this morning this is what i found- there are 12 volts to the injectors. i used a noid light and it blinked which would seem to suggest that everything is working as it should. when i go to start it it does the same thing as before- it starts immediately and then quits. knowing that the car had been sitting for a number of years, is it possible that all injectors are clogged? any help is appreciated...

[honerboys]

yep - clogged and/or stuck - after sitting for a long time evaporating fuel and other sediment will accumulate and be pushed to the injectors - their openings are very small so that's where it will clog - try the test i posted above - i've cleaned the injectors in my 84 with a hose hooked to a can of carb cleaner and a 12 volt power source - keep spraying and popping the injector - i got all of mine to spray a nice pattern doing this - again..be careful of sparks

[honerboys]

another thing - if you are going to pull the injectors to clean get new fuel lines that are rated for modern gasoline - it's a pretty easy job once you pull the injectors - lots of posts on here about those lines and some unfortunate fires

[stepson]

I have used a MityVac to put a vacuum on the top of the injector (backflow in other words) and a jig with an old injector connector and a switch to provide intermittent power to activate the injector. I put the nozzle of the injector into a small amount of Berryman's B-12 and activate the injector. When I get Berryman's into the vacuum line, I go to the next injector. Worked for me. YMMV