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Exclamation 1984 911 carrera, will not start

hey guys i'm posting out of desperation here. Ive searched for days now, replaced parts, printed out trouble shooting guides and i'm out of ideas.

i have a 1984 911 carrera, and it wont start. So heres the background. car sat for a unknown period of time. car would not start when first acquired. pulled all fuel injectors and sent out to be rebuilt and flow tested. cleaned engine of rodent nests and tree matter. replaced fuel filter, changed the oil, got a new oil filter, drained the old gas and purged the lines. i even cleaned out the fuel rails. got new injectors, filled w/ 5 gal of fresh 93 octane fuel, and she fired up, had some fun, got new tires did other things like rip the interior out and replaced it.

now the problem, i had jacked the car up, fixed an oil leak and when i put her back down she wouldn't start. i wasn't getting any spark! odd i thought. the cap and rotor are good, no cracks or corrosion. i replaced the coil and still nothing. replaced the DME relay, still nothing, replaced the fuel pump relay, no good, just finished installing a new reference sensor, and to my surprise... still wont run. "just to add in, since i didn't touch the little screw on the fly-wheel i didn't check the clearence for .08mm"

Tomorrow ill be able to check for spark cause ill have a buddy over to crank it. The fuel pump runs when jumpered. battery is new and is putting out 11.89 volts.

Thoughts? ideas? anything? very well appreciated, Sean


Last edited by trippmann; 10-13-2010 at 08:12 PM..
Old 10-13-2010, 07:22 PM
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I think your battery is a little on the low side, 11.8 will not get the injectors to fire.
You need at least 12.35 for the injectors to go, at least that is what I have discovered with my 1987 944 which has the same type of injection system as your 1984 911 Carrera.

But I am no expert, so maybe someone else will chime in with their thoughts as to what may be causing your no start.

Another thing to check is the ECU/DME brain. Lots of times these boxes get rattled around alot and the solder points begin to crack and get loose. So, if you know of someone with another car just like yours, same year/model, try and swap out the brain to see if the car starts up.

Hope this helps. Good luck.
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Old 10-13-2010, 10:31 PM
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Not to be mean sounding, but you need to stop throwing money and parts at it. There are logical steps involved and simple tools.

I agree, you don't have nearly enough voltage to run the system.
Old 10-13-2010, 10:35 PM
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Whoops! One more thing...I just re-read your post about jacking up the car, etc..

Did you by any chance unhook a ground cable? If one of your ground wires came loose, that would make the car not start-up. Just a thought.

And, as for the 11.89 volts, is that when the car is shutoff? If so, I think the battery is too low.

Also, with a new battery, when you are at idle you should be seeing voltage around 12.8-13.65 with the alternator charging the system. Might check that with a volt meter to be sure.

Does the car crank at all? If so:

Another thing to try: spray some ether/starter fluid inside your rubber boot near the throttle intake and see if she cranks and starts.

If she doesn't even crank, then, well, that was no help and you will need to start checking the flow of current through-out the car.
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Old 10-13-2010, 10:39 PM
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car cranks no problem. problem is that it doesnt have spark comming from the coil. ill charge the battery today and give it a shot later. i havnt just been throwing money at it either. ive taken logical steps to why the car wouldnt run and doesnt have a spark
Old 10-13-2010, 11:45 PM
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12.6 V = 100% charged battery, as measured at battery posts, car off.
12.4V= 75%
12.2V= 50%
12.0V= 25%

.....see where this is going?.... you have a "dead" battery.
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Old 10-14-2010, 05:24 AM
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If you are in Doubt about your DME unit you can always send it to us for a free testing .But as everybody agrees you should have over 12.5 Volts while cranking to fire up the system.
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Old 10-14-2010, 05:40 AM
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I agree with others that the battery should be over 12 V at rest. But the Bosch DME will start the car even when the system voltage drops below 11V during cranking. So I doubt this is your issue. As long as the car cranks over with a healthy sound it should fire.

First off ensure the basic DME functions: Make sure the ICV vibrates when you turn the key to RUN but don't start the engine. This will confirm the DME is powered.

Next make sure the fuel pump is coming online when you crank. Measure at the fuse. This will confirm a healthy DME relay.

Then the next questions is: Do you smell fuel after cranking? If yes the DME produces fuel signals. And if the engine is not flooded it should start unless it has no spark or spark at the wrong time.

If you have no fuel you might try and tap the injectors with a screwdriver handle. They like to get stuck close when sitting for a long time.

If you have no fuel and no spark it most likely points to either bad sensors (speed or reference) or a bad DME.

If you have fuel but no spark it could be a damaged DME given your coil checks out fine (primary and secondary resistance in spec). Depending on where you are located you could either swap your DME into another car or get someone to let you try his DME in your car.

If that doesn't work you might want to consider getting yours bench-tested or ask for a loaner DME to try in your car. Let me know if you need help.

Cheers,
Ingo

The issue could n
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Old 10-14-2010, 09:45 AM
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ok answering ischmitz questions.

icv dies vibrate
will check the fuel pump tomorrow.
i smell fuel down at the exhaust after cranking
tapped all injectors, still not running. all injectors were serviced at witch hunter performance.
reference sensor was replaced. speed sensor *from what ive read* will not cause a no start situation, just a poor running situation
ill attempt to find a generous soul to swap computers with.

just to add, today i was looking at the dme relay, on the wire harness side, the black wire on the bottom right side is nearly snapped off, only 2 of the x amount of threads are still attached. does anyone know where i can get those mettle connectors.
Old 10-14-2010, 08:25 PM
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Let us know what you find when swapping another DME in. If everything else fails consider getting yours checked. Or let me know and we can work out a loaner.

To fix the wiring you need to release the contact from the connector housing and resolder the wire. Use a small sharp screwdriver to release the spring clip.


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Old 10-14-2010, 10:56 PM
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I have a 84 Targa and had a similar situation. Assuming that you have checked and/or replaced the DME relay, don't have a bad ground connection and the ignition system is in good working order the most likely problem is the Impulse (Reference Mark) Senders. There are two that you will have to replace. At Pelican they are part number 911-606-215-01-M14. Everything you did and more I tested before finally getting the issue resolved by just replacing the senders.
Old 10-15-2010, 10:36 AM
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Not very knowledgable, but my 84 up and quit on me once. Cranked, no spark. TRE determined it was an internally shorted injector that sent a screwy signal, or no signal back to the DME. You pulled your injectors, to work on them. You might check that.
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Old 10-15-2010, 10:44 AM
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Sean,
Hop over to Rennlist and you will find a very good tech article about non starting carrera's
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Old 10-15-2010, 10:55 AM
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Check the ground wires again, and the three stacked connectors on the left side of the engine and make sure they are still connected properly.
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Old 10-16-2010, 10:16 AM
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bump for more ideas
Old 10-22-2010, 06:13 PM
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? You need to give more updated info than that.

Old 10-22-2010, 06:36 PM
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