tarix

My poor 911 was driving along the 405 when the engine died completely. Got off the freeway and got it towed home. (Was only a few miles away.)

It currently will not start. Battery is good, starter sounds strong, fuel pump works. Sometimes it'll turn over 1 or 2 strokes, but never more than that. I believe it is also leaking fuel when the ignition is hot. (This is something that's sort of new.)

I know all of the things I could/should check to track this down. All I'm looking for is expert advice and opinions and things I should try first to save myself some time and money. Hopefully someone has seen something similar!

- Mike

fixnprsh

it just cranks a few revolutions then just stops turning over completely?

PorschePhD

First check for spark. Do the lights on the dash come on like the oil pressure light and alt? I would check for spark first then work out from there.

944ZEN

Had a similar problem on my 79' SC, it refused to start, suspected fuel pump, but it turned out to be coroded connection in the Fuel Pump relay.

CURE: A few strokes with some fine grit wet sanding paper on the contact surfaces off the fuel pump relay.

COST = 0.

Try to CHEK that out first, it's free.

jhawk1000

My 1980 SC Targa had a similar problem. It would die when it got to operating temp and if allowed to cool, would start and run until it got to operating temp again and then it would die even if on the highway. Worked on the catalytic converter first. Still did it with converter replaced with bypass. Next went to the exhaust system and replaced some hoses to try to minimize heat. No help! Next went to fuel filter and changed this part and flushed out the gas tank. Still no help. Ran car for about one hour and it died, checked spark and there was none. Felt the CD unit (Permatune) and it was hot as it could be. Replaced the Permatune unit, new coil and it runs perfectly now.

Mel

itsme-itsme

944zen wrote"Replaced the Permatune unit, new coil and it runs perfectly now."

Same thing with my 78SC. $500 fix...
Common failure and it sounds like you have the exact symptoms.

Mark Hald

Mike -

I'm curious to know what the fix was.

r911

Next time this happens to somebody - try cooling the CDI box with an ice cube, etc.

The Bosch box sure seems to be better quality than the aftermarket stuff...

tarix

No fix yet. I was busy replacing corroded battery terminals. It has a nice new optima battery in it now.

Fuel pump works properly when I do the air plate test. I had trouble doing the rest of the Bently tests.

I do get spark, but it seems weak. (My opinion of the color is yellow and not blue.) I've got a new cap and rotor on the way, but I cleaned up the old ones really good and that doesn't help. Also, the CDI has voltage in the right places. (Really strong too, then again I just replaced all the battery connects.) Also, I get the high pitched whine when the ignition is on.

Do I need to bite the bullet and replace the CDI box? A $500 fix is going to set back the cosmetic enhanments I have planned.

Mark Hald

Mike -

if the spark is weak, it COULD be the CDI box, but it could be the coil, or even a bad ground connection. Do you have a friend with an SC who would let you do an A-B test with known good components to help narrow it down?

If it's the CDI, there are used ones available for much less than $500. I bought one as a spare for $100. Of course, you're never sure how long such a replacement will last unless it's known to have been rebuilt.

Lorenfb

The spark should jump about 25mm from the coil wire to ground. If you have the
silver (big) Bosch coil, they are known for having high failure rates. The original small
911SC coils were the best. You can use a old VW coil for testing, or any coil from
an inductive discharge ignition as used on an old "points" car.

Check out this web site ( www.systemsc.com ) on the Diagnostics page under No
Start for additional info. If the CDI is bad, which is rare, you can buy
a rebuilt from Pelican Parts.

mwildt

Try to check the sparks at night!. Yep, when it's dark you'll see much more if there is sparks jumping around in place you don't want them to. Also check the wire for the pick-up sensor on the distributer. They tend to get warmed/cooled and that makes them brittle. I had to replace mine ones to fix a running problem.

Michael

tarix

Bosch CDI unit is part #0 227 300 004
Bosch Coil is #0 221 121 001

They seem like they've never been replaced. I don't suppose anyone in South Bay or SoCal has spares I can borrow for the weekend?

Lorenfb

Again, since you do have a spark, although weak, get another coil,
e.g. from Pep Boys ($20) for an old VW, to use as a tester. It sounds
like you have a bad coil. The 6 pin Bosch CDI either makes a spark
or it doesn't, i.e. it VERY rarely makes a weak spark.

Check out this web site ( www.systemsc.com ) on the Dealers page for possible
sources for a 6 pin Bosch CDI.

tarix

Loren thanks for clarifying this. I didn't realize I could get a cheap coil at a local store. The Ohm loads on my current coil test good, but it does seem like the most likely component to fail.

I'll give an update after trying to new coil.