Ignition problem troubleshooting (electrical)......
 

I'm doing a 3.0 liter ('78SC) engine installation in a '78 roller with unknown history for a fellow Pelican member. The engine runs OK in my engine test stand. New fuse panels in the luggage compartment were completely replaced and re-wired accordingly. The engine installation has been completed several days ago and ready for start-up.

So all the necessary steps for engine start-up were done. Pressure test (fuel) showed no fuel leak, electrical wiring plugged and connected, battery fully charged, control and system pressures within spec., 11 liter of engine oil added into the tank, starter cranks fast and strong, etc.

I'm not getting any ignition at all. So a spark plug was connected to plug #1 and grounded. No spark. Installed an inductive timing light and not getting any signal. CDI is getting power at terminal #15, WUR and AAR get power too when FP is energized. The alternator was removed and painted prior to engine installation. Did I miss in the re-connection of the alternator wiring?

I'm seeking help, advise, suggestion, or recommendation how to diagnose this problem. The motor runs on my engine stand so what could cause this non-ignition problem? There is something absence in the 'roller set-up' that could contribute to this problem. I'm trying to avoid pulling the engine out and have it tested on the engine stand. Thanks.

Tony

Tony,

Do you happen to have an extra CDI on hand? Maybe swap that and give it a try?



Craig

Troubleshooting for the CDI can be found in these threads:

http://forums.pelicanparts.com/porsche-911-technical-forum/474952-ignition-questions.html

http://forums.pelicanparts.com/porsche-911-technical-forum/513574-starting-problems-any-ideas.html

Are you sure the battery is fresh? I had a situation where there was enough juice to show at CDI pin, but not enough to get spark...and it was cranking fine it seemed...if it's not battery, what else is different from bench set up?

Igition problem.........
 

newms,
The battery is new and fully charged. The starter cranks very strong and no sign of sparks (ignition). The main difference between the engine test set-up and the current set-up are:
1). CDI.
2). Utilizing the engine bay fuse panel and ignition switch.
3). Vacuum line to brake booster connected.
4). Connecting the roller's chassis wire harness to the engine harness.

Lastly, the alternator was removed from the engine prior to mounting and distributor cap was pulled out for inspection.



Craig,
I went out to the garage this morning and turned the ignition switch to ON. There was no discernable buzzing sound coming from the CDI. This could be it. Thanks.



HarryD,

The attachments are very informative but they deal mostly with the earlier CDS type ignition with breaker points. And I went further by reading some section from Haynes and Bentley manuals.

I'll keep you guys posted. Thanks to all.

Tony

Search here for info on the "green wire"

here for example http://forums.pelicanparts.com/porsche-911-technical-forum/334432-green-wire.html

Jay

Troubleshooting update..........
 

Craig,

I heeded to your sage advise inspite of your refusal to admit about your experience with electrical troubleshooting. Since I don't know how to bench test a CDI, switching to a known good CDI could be a prudent course of action.

After installing the second unit (CDI), I turned the ignition switch to ON and listened very carefully for the buzzing sound in the engine bay area. What a wonderful feeling when you hear this 'sound' coming from the CDI. Went back to the ignition switch and turned it to START.

The engine came to life the very first try. The feeling and joy of seeing the engine finally run was beyond description. Thanks to everybody too.

Tony