84-911 won't start---help please

por1984 · 09-20-2004, 01:50 PM

read the various posts--so i replaced the dme relay---replaced the fuel relay---replaced the fuel pump fuse-----car turns over and over but no spark and no sound from fuel pump amd no smell of fuel flooding. any help would be appreciated.----car is totally stock with no mods. thanks bill

epbrown · 09-20-2004, 02:09 PM

Check your ignition coil?

john walker's workshop · 09-20-2004, 02:19 PM

the relay was the DME relay under the left seat right? if not, wack it with a screwdriver handle a few times and see if that helps. you can also wack the fuel pump if you can get to it. sometimes that gets them going. then obviously it needs to be replaced. if it's been raining hard, pop the distributor cap and check for condensation. carreras seem to suffer from that.

por1984 · 09-20-2004, 02:22 PM

yes it was the dme relay under the seat that was replaced with a new one. car ran fine parked in garage overnite and next day would not start.

911mot · 911mot's Garage

Check the injection loom multiplug and fuse connections/relays behind the removable panel in the engine compartment.
Have you got an immobilser fitted?

por1984 · 09-20-2004, 03:15 PM

there use to be an aftermarket alarm systen but it was totally temoved a year and a half ago.
car ran rough and backfired occasionaly before it died all together. will check fuses and relays as suggested and move on to coil.
but there still is no fuel smell or loading no matter how long you crank it. thanks and any other ideas are welcomed. bill

911mot · 911mot's Garage

With the backfiring and running rough before hand I'd definatley go with a bad connection/water ingress somewhere. Check the distributor multiplug too.

midlife · 09-20-2004, 04:00 PM

I had an intermittent problem starting the other day. After jumpering the DME relay and still not getting the fuel pump to run, I traced it to a loose wire at the fuse block.

My son's motronic 951 had intermittent starting problems, that was finally traced to a bad connector at the reference sensor.

Both cases, there would be no fuel and no spark, just cranking.

Jim Smolka · 09-20-2004, 04:23 PM

Use a jumper wire from one of the continuous 12V sources seen on the front trunk fuses panel to the fuel pump fuse. The pump should run continuously.

john walker's workshop · 09-20-2004, 05:56 PM

have someone crank it over while you feel the fuel pump with your fingertip. it should vibrate. if it is running, perhaps one of the reference sensors is toast. make sure their plugs are on securely. that's the stack of 3 on the left side of the intake, white on top, and 2 blacks below.

SpeedracerIndy · 09-20-2004, 07:12 PM

Do the 3.2s have a crank position sensor? I had the exact same problem (although not with a 911) caused by a bad crank position sensor.

pirin911 · 09-20-2004, 07:53 PM

My 1985 suffered the same disease. No spark at all. It was the reference sensor. It was open (no impedance). Changed also the speed sensor because of erratic readings in impedance.

por1984 · 08:17 PM

jumped the fuel pump and it ran continuously. fuses seem to be o.k. and dist. cap is dry and clean. i must admit i do not know about the relays behind the panel in the engine compartment.
is there a way to test them and frankly what are they for???
the only time it has smelled like gas is when the pump was running when i jumped it. thanks bill

ga_mueller · 09-20-2004, 08:23 PM

For me, anyway, this described my DME going bad. It would start sometimes, die, I could crank and not get spark or fuel, and on and on. Finally, I ohmed out every signal at the DME plug per Bentleys and found that everything was OK. I then got a rebuilt DME from Systems SC and it's run fine ever since. This was, unfortunately, the final troubleshooting I did, so now I have a lot of new components which I did not really need.

por1984 · 09-21-2004, 01:50 AM

how do i find systems sc that you mentioned?

Jim Smolka · 06:00 PM

por1984,

On your bio, please update your location. Maybe some Pelican member is near by to help by swapping the DME box

ga_mueller · 05:19 AM

Quote:

Originally posted by por1984
how do i find systems sc that you mentioned?

www.systemsc.com

They will give you a DME "loaner" for $75 to troubleshoot your problem. The owner (Loren) is very, very knowledgable if a bit crotchety.

(ps Not gonna swap MY DME to troubleshoot! Too risky!)

Jascha · 06:21 AM

I suggest you check the TDC (reference) sensor

Use an ohmmeter to check the resistance (3 pins) at the 3-sensor connector in the engine compartment

I posted the other day the exact combination and R-values...

Wil Ferch · 09-21-2004, 06:07 AM

FYI....you continually state that that you don't hear the fuel pump running, can't smell fuel, etc...

Be advised that the properly functioning system will not allow the fuel pump to run ( and no smell, obviously), when the engine is *not* running.....

Wil

PS--- I too would focus on the two sensors that look at the flywheel teeth.

ga_mueller · 06:15 AM

Quote:

Originally posted by Jascha
I suggest you check the TDC (reference) sensor

Use an ohmmeter to check the resistance (3 pins) at the 3-sensor connector in the engine compartment

I posted the other day the exact combination and R-values that

I too did the "check this and check that" routine for my nostart problem. I realize these are all good suggestions from people who have experienced similar problems, but if you don't have a logical method to troubleshoot these sorts of problems, you'll spend tons of money and time. Get a Bentley's. and follow their procedure for testing ALL of the DME inputs at the DME plug. I wish I had done this from the start.
George