1980 porsche 911sc starting issues

adamsison · 03-01-2013, 12:00 AM

hey everyone,

i have a 1980 porsche 911sc.

it wont start, the battery is charged, the fuel pump engages, the relays have all been changed.

it used to do this, then after a couple of tries or leaving it for 30 mins or so. it would then start.

but now for the last 3 days i am unable to get it going unless i push start it.

any ideas?

its going to a porsche specialist in a weeks time, but whilst i still have it hear, i want to try and get it going myself.

Cheers
Adam

theFONZ · 03-01-2013, 12:50 AM

Does it turn over? Does it sputter? Do you just hear a click when you turn the key? With no more info, I'd guess starter or solenoid. Try tapping the starter with a wrench or something and see if it will start then.

al lkosmal · 03-01-2013, 05:58 AM

Adam,

You need to provide a bit more info for us to provide you with some help.

but here are a couple simple checks, based on a broad assumption.

If your starter is not turning the engine over to get it started, but you can push start it, I'd check the ground strap that is located by the transmission mount. Remove it and clean all the mounting surfaces and try starting again.

I'd also check to see that the yellow wire is connected to the starter. If it is disconnected the starter will not be energized.

regards,
al

PS: Provide some more info and we can go from there.

adamsison · 03:00 PM

Quote:

Originally Posted by theFONZ

Does it turn over? Does it sputter? Do you just hear a click when you turn the key? With no more info, I'd guess starter or solenoid. Try tapping the starter with a wrench or something and see if it will start then.

all the accesories work, i can hear the fuel pump ,
but when i turn the the key it doesnt click, it doesnt turn over at all = no spluttering.

im assuming its the starter motor or the solenoid.

ToddM · ToddM's Garage

Starter solenoid.. common failure.

al lkosmal · 03-01-2013, 06:07 PM

Quote:

Originally Posted by al lkosmal

Adam,

You need to provide a bit more info for us to provide you with some help.

but here are a couple simple checks, based on a broad assumption.

If your starter is not turning the engine over to get it started, but you can push start it, I'd check the ground strap that is located by the transmission mount. Remove it and clean all the mounting surfaces and try starting again.

I'd also check to see that the yellow wire is connected to the starter. If it is disconnected the starter will not be energized.

regards,
al

PS: Provide some more info and we can go from there.

Adam,
Start with the simple stuff 1st. I've fixed two no-start conditions by cleaning/replacing the ground strap and one by plugging the yellow wire to the starter back in. If that doesn't work for you....move on to the more costly and difficult.

regards,
Al

Hunt3R · Hunt3R's Garage

Quote:

Originally Posted by ToddM

Starter solenoid.. common failure.

What he said.

Same thing just happened to me. Same symptoms you describe, and it was intermittent at first too, then left me stranded unless push-started. Then it would start again the next day. Then for the next 3 days it wouldn't. I followed this tech article to verify it was the starter solenoid but suffice to say the new starter works great.
http://www.pelicanparts.com/techarticles/mult_starter_diag/mult_starter_diag.htm

adamsison · 03-02-2013, 02:38 PM

so if the starter solenoid is gone, does that mean i have to change the starter motor?

ossiblue · 02:54 PM

Quote:

Originally Posted by adamsison

all the accesories work, i can hear the fuel pump ,
but when i turn the the key it doesnt click, it doesnt turn over at all = no spluttering.

im assuming its the starter motor or the solenoid.

Here's another potential problem. Your post indicates that the fuel pump is running even when the key is not in the start position. If that's the case, your fuel pump relay circuit is faulty. The fuel pump should not run unless the engine is running or the engine is rotating by the starter motor (and it would be difficult to hear the pump due to the noise of the starter.) It could be the relay, intake safety switch, or wiring to the switch. This is a separate issue than the failure of the engine to turn over via the starter. Get that taken care of and then address the fuel pump issue.

adamsison · 03-04-2013, 10:56 PM

Thanks for all the replies everyone

As most of you thought, it was the starter solenoid.
It's getting replaced, and I have asked my mechanic
To clean out the ground strap and all the wires in that area.

aquazulu2 · 03-05-2013, 04:22 AM

I had a similar problem, in checking the fault I jumperd the sylenoid and the main starter connection, starter worked, with the jumper but not at ignition. Fault was found to be a coroded ground strap bolted on transmission and frame. Braded ground strap left of the starter.

ossiblue · 03-05-2013, 06:33 AM

Quote:

Originally Posted by adamsison

Thanks for all the replies everyone

As most of you thought, it was the starter solenoid.
It's getting replaced, and I have asked my mechanic
To clean out the ground strap and all the wires in that area.

What about your fuel pump? Does it run with the ignition on but the engine not running, as implied by one of your posts? If so, fix it also.