Find a friend willing to swap DME's with you to test.

The fuel pump only runs with the key in start position or the engine running.

do you have 12 volts in the harness on 1, 14, 15, 18, 35
ground in the harness?

Unfortunately I do not have any friends with Porkers and 3.2's are like rocking horse s**t around here. Even so not all 3.2's have the same DME aprt number - Mine is 911.618.111.07

Err....yes I realise that.

Does anyone know about any continuity tests on the DME. I have put an Ohmeter on the pins of the DME and the all have an impedence with the other pins except #12.24.30.31.32 which have no signal to any other pin. I have not tested the harness yet.

So you have a meter and know how to use it.

Why not measure between pins 1, 14, 15, 18, 35 in the wire harness and chassis with the key on. Then put it on ohms and measure continuity to ground through the harness at the specified pins. Then just for grins put it on AC and measure the speed sensor output while cranking the engine.

Chateau:

My only experience with a Carrera "no start" was with my 87.

Run all the diagnostics found in the Bentley and follow the advice of the "experts". BUT, if all that fails to help (I hope the "standard" diagnostics point you in the right direction and you can get your car running quickly) you may want to inspect the solder joints on your ECU to make sure they are all good.

I went through the same thing. I began to question every meter reading and test I was conducting because I was not getting results that pointed to a clear fix. Finally, Steve W offered to let me plug my ECU into his Carrera. Guess what, his car would not start with my ECU--PROBLEM AREA IDENTIFIED! Then, Steve looked at my solder joints with a magnifying glass--SPECIFIC PROBLEM IDENTIFIED! Steve re-flowed the bad solder joint and, VOILA, his car started right up with my ECU. My car has not so much as hickuped since.

Despite some "EXPERTS" opinions, the fact is Carrera ECU's are getting old. Some of the solder joints on the circuit board are apparently degrading and this is NOW one of the areas that should be considered when experiencing a no start on a Carrera 3.2.

I will attach a photo of my failed ECU solder joint. If you feel comfortable opening your ECU up, you may get lucky and find the problem.

Best of luck toward a speedy and inexpensive fix. If you were anywhere near me in Los Angels County, I would welcome you to come by and plug your ECU into my car.

Mike

My ECU (photo by Steve W)

http://forums.pelicanparts.com/uploa...1208035122.jpg

+1 on this gent's observations!!



Best,

The 2nd DME relays stage for the fuel pump is controlled by a simple OR function. One input is the cranking signal from pin 4 (hot when cranking) and the other comes from the CPU (hot when proper flywheel motion is detected). It uses a Darlington transistor as a low-side switch to provide GND to pin 20 to switching the relays on.

You need a break-out box to test whether this function is working. If not the Darlington could be open.

BTW: Have you checked whether the ICV hums when the ignition is in the ON position? If it is not humming and the DME relays is not switching on the fuel pump when cranking I suspect something is wrong with your external wiring.

These two functions are completely isolated inside the DME and it is unlikely that both fail at the same time.

Ingo

Hi All,

Here are the latest stats using a battery jumped from another running vehicle to the battery on the 911:

There is continuity between the DME case and Ground
-----------------------------------------------------------------
Ignition ON:

Testing pins to Ground Voltage on wiring harness:

1 (Coil ground) 12.75V
14 (Injector control signal) 12.77V
15 (Injector control signal) 12.77V
18 (+12 V) 12.77V
20 (Control signal, DME relay) 13.61 - Drops while cranking
35 (+12V) 12.77V
------------------------------------------------------------
Ignition OFF

Testing pins to Ground on wiring harness:

1 - 46 Ohms
14 - No continuity
15 - No continuity
18 - No continuity
35 - No continuity
--------------------------------------------------
While cranking AC volts on Speed sensor pins on wiring harness:
Pin 8 - 1 Vac
Pin 27+ 0.6Vac
-------------------------------------------------
While cranking DC volts on Pin 4 (t54,starter active) 10.48Vdc
DC volts between Pins 4 and 20 IGNITION ON = 14.15Vdc - drops to 375 mV while cranking.
-----------------------------------------------------------------------------

The ICV is humming

The Fuel pump is not pumping - If I remove the Relay and jump the pins the pump works.

Fuse 3 has 12.9 Volts when the key is ON

RELAY REMOVED - KEY OFF
Battery voltage at terminal 30 on Relay plug = 13.02V

RELAY REMOVED - KEY ON
Battery voltage at terminal 86 on Relay plug = 12.94v

Terminal 85 on Relay plug is grounded

RELAY CONNECTED - KEY ON
Battery voltage at terminal 87 on DME relay = 12.9v

The Relay clicks when the key is turned ON

COIL

- to GROUND 47 Ohms
+ to - 1 Ohm
+ to Ground 45.6 Ohms

12.9 Volts on the + to Ground on the engine casing

I have taken the DME apart and I can see new solder from when I sent it away. I do not seem to see any other cracked joints.

having the same problem with my 84 911- put it in storage for winter.... new battery, DME relay, still no start?

Injectors stuck shuit - tap them with a screwdriver handle while cranking and it will spring to live....