My 911 3.2 Carrerra won't start!

[af1960]

Having had the faulty DME relay experience, I thought that I had a repeat of the same problem when I could not start my 1985 3.2 Carrera again. But a new relay did not achieve anything.

The fuses under the bonnet all look OK

The DME relay clicks when I turn the key and the engine turns over, but not a sign of life.

I have been told that it may be the crankshaft sensor which needs cleaning/replacing.

Can anyone give me clue as to where it is, please?

[cdrik915]

Can you ear the fuel pump working and is there sparks on ignition ?
Pmh /pmb sensor can be a thing to see ,behind the left wheel.

[MBEngineering]

HI af1960
the sensor connections are in the engine bay on the L/H side, on the 3 connectors in the photo,



the sensors are near the gearbox bellhousing on the pass'side of the engine, so if you remove the L/H rear wheel you should see the sensors on a bracket like this ( the photo was taken from above).






the lower photo shows the gap on the sensor to the flywheel, and in the photo the wires are exposed to the heat of the exhaust and should have the tin work like this



to keep the heat off the wires , check your tin work is OK ,as the wire's could be cooked??.
I have sensor readings if you cannot find them on hear, if you would like them.

regards mike

[DonMo]

If you have a friend with a 3.2, you might be able to save yourself a lot of headache. Swap the Motronic/DME/ECU. If your car starts, you know where your issue is. There is a history of cold solder joints and heat related component failures on our cars. Ask me how I know? At least now, I have new sensors and a repaired DME.

[911mot]

Has it been standing? Clean the fuse holder for the fuel pump fuse (front fusebox under bonnet), they tend to corrode in this weather.

[af1960]

Thanks for all the good advice, chaps!

I'll get my overalls on and get checking.

Adrian

[ZOA NOM]

Try this chart...

[MBEngineering]

HI af1960
or there is the factory test sheet;
for educational reference only.



and if you do get stuck, I have a test plan if you PM me your snail mail Add',




regards mike

[brcorp]

Originally Posted by MBEngineering

HI af1960
or there is the factory test sheet;
for educational reference only.



and if you do get stuck, I have a test plan if you PM me your snail mail Add',




regards mike

Mike,

Does the manual discuss diagnostics of the ECU? If so I'm in need of some direction

[rick-l]

First thing to do is see if you have a spark

[Quicksilver]

Someone already asked if you can hear the fuel pump running. It will only run when the DME sees the engine is turning so to test it jump the DME relay to force the pump on. Jumping connector 30 to 87b will send power to the fuel pump. Can you hear it run?

When you crank the engine you should see the tach move a bit. If not check the crank sensors.

After trying these two things if you still have a problem come back for more...

[Ray B]

Possibly the fuel pump- as has been mentioned. After taking all necessary steps to keep yourself from being run over , you might try tapping the fuel pump whilst a helper cranks the car. You can get to the pump by inserting a screwdriver (or similar) between the chassis and pump cover and tapping with a small hammer or such. You don't need to beat the tar out of it- just loosens the contacts within. It's worked for me several times.

[lindemans]

The DME relais actually contains 2 relais units.
If your hear one click, the other my be failing.
Furthermore faulty relais may click but not fully engage the switch.

I would not eliminate the relais as cause due to its clicking alone.
Have you tried tapping its housing with a screwdriver while starting ?

[John I]

I have been using this thread to help me when my 87 Carrera has been giving me starting problems.
I thought I would share what my problem was and fix, to help others.
My 87 Carrera was running great as a daily driver until I was driving on one raining Los Angeles day, I stopped for a few minutes and it wouldn't start back up. The engine Cranks over well, but not even a sputter. No fire.

I parked the car for about 6 weeks until I could get to working on it. After 6 weeks of sitting, I tried and it started up normally.
So I started driving it again.

The other day driving into work, it just died in stop and go traffic, but started right up again. After the work day, I was driving home in the #1 lane on the freeway, in stop and go traffic, and the engine died, and won't start. Just cranks and cranks.

Thank you to the two guys who pushed me to the side, off the shoulder. Another guy stopped and helped me install a new battery I just bought and had in the trunk.

So now I have full battery power, and a gremlin to chase. I pulled the relay under the seat, looked at it for burning marks or any damage. It looked ok. I tapped on it in the hopes that is what it needed to work if it was faulty. I took the cover off the DME, looking for bad solder. Everything looked good.


I got a flashlight and a can of starting fluid from a parts store in walking distance. I sprayed the either in the airbox Intake. The engine fired for a few seconds. So now I am pretty sure the ignition and DME is functioning, but the fuel system is giving me problems.

I cut a speaker wire to make a little bridge on the 30 and 87B relay Pins, as Wayne described above. In case the relay is bad, I can force the pump on. (Hi Wayne, I hope your move went well. I miss you over here. Maybe see you in September?)

It dosnt help. I can't hear the pump come on, but I don't think I ever did when the car was running anyway.

As I Crank the engine over, the tach needle moves a bit. This hopefully means my flywheel sensors are OK.

Ultimately, I jacked up the car, the next morning, and took off the front drivers wheel. I tapped the fuel pump with the handle of the lug wrench a dozen times. As I cranked the engine a helper tapes it again, the engine fired up.

I put the wheel back on and drive to work.

The car got me home from work that afternoon, and I parked it in the driveway to put a new Bosch fuel pump in.

I ordered a few relays to have onboard just in case as well.

I hope this helps someone.

John

[Hnichols]

Originally Posted by DonMo

If you have a friend with a 3.2, you might be able to save yourself a lot of headache. Swap the Motronic/DME/ECU. If your car starts, you know where your issue is. There is a history of cold solder joints and heat related component failures on our cars. Ask me how I know? At least now, I have new sensors and a repaired DME.

I'd second this. As someone also said, check for spark -- that's easy enough. If you don't get spark and your DME doesn't start a friend's Carrera, then chances are years of vibration caused cracks in the solder joints in the ignition circuit.

(Don't try your friend's DME/ECU in your car; try your DMW/ECU in his car.)

Replacing speed and reference sensors is not that bad, but you don't want to do it unless you're pretty sure that's your problem. Depending on the history of your car, they may have been changed before, esp. if they're missing the DG/BG tags on the cables in the engine compartment.

Good luck!

[TipToe]

Originally Posted by John I

I have been using this thread to help me when my 87 Carrera has been giving me starting problems.
I thought I would share what my problem was and fix, to help others.
My 87 Carrera was running great as a daily driver until I was driving on one raining Los Angeles day, I stopped for a few minutes and it wouldn't start back up. The engine Cranks over well, but not even a sputter. No fire.

I parked the car for about 6 weeks until I could get to working on it. After 6 weeks of sitting, I tried and it started up normally.
So I started driving it again.

The other day driving into work, it just died in stop and go traffic, but started right up again. After the work day, I was driving home in the #1 lane on the freeway, in stop and go traffic, and the engine died, and won't start. Just cranks and cranks.

Thank you to the two guys who pushed me to the side, off the shoulder. Another guy stopped and helped me install a new battery I just bought and had in the trunk.

So now I have full battery power, and a gremlin to chase. I pulled the relay under the seat, looked at it for burning marks or any damage. It looked ok. I tapped on it in the hopes that is what it needed to work if it was faulty. I took the cover off the DME, looking for bad solder. Everything looked good.


I got a flashlight and a can of starting fluid from a parts store in walking distance. I sprayed the either in the airbox Intake. The engine fired for a few seconds. So now I am pretty sure the ignition and DME is functioning, but the fuel system is giving me problems.

I cut a speaker wire to make a little bridge on the 30 and 87B relay Pins, as Wayne described above. In case the relay is bad, I can force the pump on. (Hi Wayne, I hope your move went well. I miss you over here. Maybe see you in September?)

It dosnt help. I can't hear the pump come on, but I don't think I ever did when the car was running anyway.

As I Crank the engine over, the tach needle moves a bit. This hopefully means my flywheel sensors are OK.

Ultimately, I jacked up the car, the next morning, and took off the front drivers wheel. I tapped the fuel pump with the handle of the lug wrench a dozen times. As I cranked the engine a helper tapes it again, the engine fired up.

I put the wheel back on and drive to work.

The car got me home from work that afternoon, and I parked it in the driveway to put a new Bosch fuel pump in.

I ordered a few relays to have onboard just in case as well.

I hope this helps someone.

John

I am experiencing the same issues....I put a new DME Relay and the 911 wouldn’t even turn over...so I put the old DME back in and it started right up.....I’m suspecting that I have a bigger issue than just a DME relay.

John, what fixed your problem?

[John I]

I put in a new fuel pump. It is right under and behind the gas tank. I'm using the same DME, and Relay.

When these fuel pumps die, they do so intermittently, and sometimes operate noisily. Also, if your car sits a long time, I believe this can make the fuel pump go faulty.

I'll be keeping a new fuel pump and relay in the trunk now for spares as I drive around.

John

[mrrolleyes]

i see posts about fuel pumps.

pull the relay and short the pump with a wire. its pin 30 and 87 or 87a and the pump should kick on when when you turn the key. before you start diving into bigger things.

[Quicksilver]

Originally Posted by John I

. . .

I cut a speaker wire to make a little bridge on the 30 and 87B relay Pins, as Wayne described above. In case the relay is bad, I can force the pump on. (Hi Wayne, I hope your move went well. I miss you over here. Maybe see you in September?)

It dosnt help. I can't hear the pump come on, but I don't think I ever did when the car was running anyway.

. . .

To jump the relay so the car will run you need a 3-way jumper for 30, 87b, and 87. The extra relay powers up the injector circuit. (Make sure that you don't leave the jumper on the car when it isn't running.)

The fact that the fuel pump started up when you tapped it says the fuel pump is toast. While you are there replace the rubber portion of the fuel lines. Use a Dremel to slice diagonally through the crimp sleeves to take it apart.

----------------
Yeah John. I'm going to start driving next week and I'll be camping up near Turn 6.
I'm leaving the car in Cali til the Targa Baja California at the end of October.
(Don't worry. I've added MORE lights on the Pooch for Baja.)