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-   -   My car won't start! (http://forums.pelicanparts.com/porsche-911-technical-forum/549663-my-car-wont-start.html)

jdale442 06-23-2010 07:19 PM

My car won't start!
 
Any help troubleshooting would be greatly appreciated! It's '84 911 Cabrio, stock, with 50K miles. It's always run perfectly (at least since I've owned it 5 yrs), one day just wouldn't start. Turns over fine, no spark. Any ideas?

Christien 06-24-2010 05:08 AM

Do a search for no-start. Not to sound like a smart-ass search nazi, but I know this has come up here a billion times. It's either fuel or spark you're missing, and checking to determine is fairly straightforward.

Drisump 06-24-2010 05:21 AM

I don't want to sound like a one hit wonder but an easy place to start is your DME relay located under your drivers seat. If you (or your cars previous owners), haven't already done this, it's time anyway (about $35). Cheers

JJ 911SC 06-24-2010 05:25 AM

Quote:

Originally Posted by Christien (Post 5421067)
... It's either fuel or spark you're missing, and checking to determine is fairly straightforward.

Unplug one of your spark plug, plug a good spark plug into the lead, ground it, have someone start the car and check for a spark.

This will either eliminate or point to an ignition problem.

JJ 911SC 06-24-2010 05:28 AM

and don't forget...
 
... to introduce yourself properly :D:D:D with photos.

Welcome to the board.

P.S. 3 Canucks replie in a row!!!

RexNoctu 06-24-2010 05:31 AM

When you say no spark, have you pulled a plug and verified that it isn't sparking? Can you smell gas as it is cranking?
Agree with the above about the relay being a good place to start. Plus it is good to have one with you just in case you die by the side of the road.
If you have spark but no fuel check the fuel pump, jump the fuse for it to a live contact and verify that you can hear it spin up as a quick check. I just had to deal with one of them myself a month or so ago.

Welcome to the board and to beat the rush how about a pic of your ride so we can all drool. :)

86 911 Targa 06-24-2010 06:57 AM

Quote:

Originally Posted by drisump (Post 5421089)
i don't want to sound like a one hit wonder but an easy place to start is your dme relay located under your drivers seat. If you (or your cars previous owners), haven't already done this, it's time anyway (about $35). Cheers

+1

Also, perhaps the flywheel sensors?

Good luck,

Gerry

scottb 06-24-2010 10:41 AM

Quote:

Originally Posted by Drisump (Post 5421089)
I don't want to sound like a one hit wonder but an easy place to start is your DME relay located under your drivers seat. If you (or your cars previous owners), haven't already done this, it's time anyway (about $35). Cheers

I replaced mine before the old one failed, and then I tossed the old one into the glove box as a spare. Cheap insurance!

jdale442 06-26-2010 08:37 PM

I haven't had a chance to log on in few days. Thanks for the replies; I did pull a plug wire and grounded a new plug, had my wife turn it over, no spark. There is a fuel odor in the exhaust after turning over so I'm pretty sure it's an ignition problem. Sounds like a replacement DME relay is the best place to start.

Thanks again for the advice!!

Hodgey 06-28-2010 03:35 PM

JDale442
 
How you doooooin?????.....you just couldn't wait for me to get back to you could you mate?
Anyway, the relay is under the drivers seat as you originally thought.......just so you know!!!!

Stacey is the cutest troubleshooter you're ever gonna have Mr.........

BTW, my baby may be back with me this week....will send you pics!!!

Mill B'Stard

Hodgey 06-28-2010 03:37 PM

......oh and John........it's courtesy to post pictures of your little babies to introduce them to us all........ :)

dsmithwc04 06-29-2010 10:52 AM

I had the same problem. It was one of the red fuses (3rd or 4th from the left when facing the fuses) that had slipped out caused by the lead wire screws becoming loose. Check this and you may have a fix. Since you have a fuel smell probably not the fuel pump being stuck.

jdale442 07-02-2010 07:53 PM

OK, I replaced the DME relay tonight, no change. I did notice that the tach stays on zero when cranking over. Any more ideas?

Drisump 07-02-2010 09:11 PM

Examine coil and power to it, lead from coil to distributor, cap and rotor..... other than those, it may be more involved....I'm not sure of all the conditions the DME needs to see before allowing power to go to the coil. If your starter is turning, you would think your engines grounding would be fine, but you should probably have a look. Sorry buddy, It is likely a very small issue, but I realize your 911 times a-wasting!

JJ 911SC 07-03-2010 01:34 AM

Been there...
 
Quote:

Originally Posted by jdale442 (Post 5435801)
OK, I replaced the DME relay tonight, no change. I did notice that the tach stays on zero when cranking over. Any more ideas?

I had a similar problem and it turn out to be a broken (not blown) fuse in the engine compartment.

Before finding the actual problem, I end up putting 12 Volts (from the the rear fuse panel) directly to the coil and ran with that for a week.

Post pictures... of you car, it always help to get more help.

ischmitz 07-03-2010 05:11 AM

jdale442,

if you get fuel but no spark you have effectively narrowed things down to the ignition system or maybe the flywheel sensors.

Make sure the coil shows +12V at both sides when the ignition is ON but you don't crank. This will rule out a fuse. check the resistance of the secondary with an Ohmmeter. Also verify the rotor and distributor are in good shape.

I suspect your DME could be damaged. When you crank the DME (not the DME relay) provides GND to one side of the coil for several milliseconds at a time. This generates the spark. You need an oscilloscope to verify this. I suggest you find a fellow Porsche owner close to you (where are you located?) who lets you swap your DME into his car or vise versa. Any 3.2 will do. This quickly tells you whether the DME is the culprit.

Ingo

Hodgey 07-04-2010 08:34 PM

John

I think you can discount the fuel pump....this is from a post about a guy whose car wouldnt stay running when starting....


"First, the fuel pump is not supposed to run with the key to ON. It only runs when you crank or when the flywheel rotates with more than 200RPM. So no worries there."

Mill B'stard

jdale442 07-05-2010 08:17 AM

Thanks for the info on the fuel pump Mr. Neil. I'm going to check the coil as suggested; sounds like with ignition on, either terminal should have 12V. to ground. Anybody know what the correct resistance should be on the secondary?

jdale442 07-05-2010 09:30 AM

OK, I checked the coil terminals with the ignition on, but not cranking over. I got a little over 12 volts on each terminal. I pulled the distributer cap, there was some minor corrosion but overall it looked really clean. I'm having some diffculty getting the cap back on, but i think it just takes patience.

Hodgey 07-05-2010 12:35 PM

John
I should get my little baby back this week complete with Bentley Manual.
When I do, let's get to troubleshooting this thing and put it to bed!!!!!

M B


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