[BobNovas]

cranks but no vroom vroom. DME Relay?

[markwemple]

Check for spark and fuel and compression.

[Jazzbass]

Originally Posted by BobNovas

cranks but no vroom vroom. DME Relay?

Start there - you can jumper the connections to get it out of the circuit (do a search here - someone explained how to do it once). Check the fuse for the fuel pump.

Does it make any noise when it cranks (trying to start, etc)?

[BobNovas]

Just the cranking noise. No ignition noise. I pulled the DME relay and opened it up - it looks good to me. I'll check the fuses in the morning.

[Der ABT]

if its still a mystery something similar happened, car would crank but it was as if no spark/fuel, everything else was find, oh and it just shut down while at shenandoah (in the bumps)
i have a bad brain do this too me, basicallly the chip was loosing connection (its a rebuilt and things where just loose) if you have another brain that will work try it out if all else fails jsut shake the dme and hope the connection corrects itself (thats what mind did on the tow home haha..

[BobNovas]

Should the fuel pump run when the ignition switch is in the run position? I get no current draw through the fuel pump fuse with the ignition switch in run. (removed the fuse and put an ammeter in line)

[William Miller]

Yes, the fuel pump pumps the fuel in a loop to keep it cool. Pressure regulator keeps required pressure in the fuel rail and allows the rest to return to the tank.
There is a fitting on one of the fuel rails to hook a gauge and check pressue.

Bob, I'm chasing the same problem in a 944.
Bassically the same system.
The DME jumper should turn the fuel pump on and eliminate that and the alarm (If any) from the equation.

Also bassically the same terminals on the DME relay socket.
It's a pretty quick and easy test.

Yours should be relativly east to get to as well.

[Jazzbass]

Originally Posted by BobNovas

Should the fuel pump run when the ignition switch is in the run position? I get no current draw through the fuel pump fuse with the ignition switch in run. (removed the fuse and put an ammeter in line)

With the car NOT running? No. The 2nd half of the DME relay controls the fuel pump. This part of the relay is only switched on when either:

a. The key is in the Start position or
b. The DME senses that the engine is running (> 600 rpm IIRC)

If both these conditions are false, the fuel pump part of the DME relay is off and the fuel pump shouldn't run.

[OldTee]

What was the last maintenance or repair done to the car?

See page 240-6 in your Bentley. If you don't have one (Item 2) tow the car to Matt DeMaria! Be careful not to fill your cylinders with fuel by cranking. If you have cranked a lot, let it sit overnight to avoid expensive bent rods.

A Motonic should start right away. Possible you have a void in the fuel line. Remove the large test nut (don't loose the bb) on the fuel rail jumper the fuel relay (see above) to get the air out. One second should do it.

There are a lot of things that could keep it from running. Like reference sensor, cylinder head sensor etc. Needs test equipment. See item 2.

[smdubovsky]

Originally Posted by OldTee

Be careful not to fill your cylinders with fuel by cranking.

IMO, I don't think this is possible in a 911 by just cranking (to bend a rod). The exhaust valve is on the bottom. The cyl can't fill more than a couple mm before you just start pumping it out into the headers. Most other 'upright' engines can fill.