Intermittent starting issue

1978targasc · 06-20-2010, 08:01 AM

I need a little help...I have a 1980 sc that will not start after breakfast... any ideas. I have allreay tried switching out the fuel pump relay but no luck. This has happend once before but started later the week at home. I let it sit for an hour but am heading back to try again.

Thanks

1978targasc · 06-20-2010, 08:03 AM

It is cranking fine but will not turn over

ischmitz · ischmitz's Garage

I think you meant to say: It is cranking (aka turning over) but the engine never catches or fires.

Well, you have to start with the basics: The engine needs fuel and spark (and of course air) to start. So first you need to figure if it is the spark or the fuel that is absent. That will lead you where to look for the issue.

Checking for spark is fairly straight forward. Get an old spark plug and connect it to one of the spark plug wires. Then hold it with the metal body to a metalic part of the engine or intake track and have an assistant crank. I use leather gloves to I don't get sparked myself. Once the engine is cranking you want to see a nice bright spark. If not you found your issue.

BTW, with the ignition to ON can you hear your CDI box whining? This is a pre-requisite for it being able to deliver sparks. However, even if it is whining this by itself is not a clean bill of health. You could still be missing the trigger signal from the distributor.

When checking for fuel you need to press on the sensor plate in the intake manifold. For that you need to remove the air cleaner housing. However, a quick and dirty test would be to spray starter fluid into the air cleaner and then try to crank. If the engine jumps to live only to die a few seconds later you can conclude it was missing fuel.

Ingo

1978targasc · 06-20-2010, 08:24 AM

No luck after an hour.....

Any ideas still stuck in a parking lot

stealthn · 06-20-2010, 08:27 AM

Starter....just my guess

1978targasc · 06-20-2010, 08:30 AM

I am going to head home and change and get out of these church clothes. I will grab an extra spark plug my timing light. There was fuel in the air box and I heard the fuel pump and cis fan running.

1978targasc · 06-20-2010, 08:32 AM

The engine was cracking fine at 500 rpm sounded like it always does. I autocrossed yesterday so I checked all the fuses to make sure they were snug. This one doesnt have a dme relay.

wswilburn · 06-20-2010, 09:24 AM

Keep in mind one interesting feature of SCs. If the battery is low, the CDI can stop working, even if the starter motor can still turn. This probably isn't your primary problem, but if you keep trying to crank with no start, it may become an additional problem and confuse things.

1978targasc · 06-20-2010, 01:38 PM

Success!!

We checked spark to verify the CD box and it checked out fine, and changed out a couple more relays to no avail. We sprayed carb cleaner up into the throttle plate area and it still wouldn't start. I noticed that I didn't hear the fuel pump up front so after jiggling with the wires behind the fuel pump relay, it fired right up!

Thanks everyone for your help, and I'm glad that with some wire crimpers I should be able to fix it and not a $300 MSD box.

Michael

James Brown · James Brown's Garage

Yes!!!! Remember those troubleshooting procedures and carry that spare plug with you unless you like to get zapped! While in there, check the other wires under the relays.