993 95 crancking without starting

[Om85an]

Hello every one,
I have an issue with 993 1995 with drive block system.
The car was sitting for almost 2 years. We replaced the battery.

Car cranking not starting. Doesn't seems to start
We confirmed spark available, timing is correct.
Fuel pump not starting.
We confirmed signal available from immobiliser to ecu available ( pin 27), pin 18 also have power.
DME relay replaced. First stage power of relay available.
Pulse sensor replaced and gapped correctly to 1 mm.

We noticed only 1.2 v supplied to pulse (crank position sensor) sensor from ECU.
Any body knows How much should be the power. And how to further diagnose the non start issue

[Kein_Ersatz]

Fuel pump not starting is the problem, need pressure at injectors.

Have you confirmed power to the full pump or not at the fuel pump?

Have you bench tested the old (and new) DME Realys to confirm the old was bad and the new is good?

Force 9 has a new version of their digital DME relay will diagnostic LEDs.
https://www.ftech9.com/new-products


Some have had problems with the fuse box itself where the DME is plugged into.

[TorqueHead]

Fuel pump may be seized. Have you measured the current draw at the pump?
My pump was seized solid but it did not blow the fuse.

[Om85an]

Fuel pump is fine, it run perfectly and building pressure.
However, no signal passed to it.
I believe with 993 fuel pump should run once final stage of ignition closed, the later should close once ECU sees signal form crank position sensor

My suspect is the crank sensor not getting powered by the ECU through terminals 48-49. I just needs to confirm it. Only 1.2 v available at positive terminal. Any ideas??

[mysocal911]

Originally Posted by Om85an

Fuel pump is fine, it run perfectly and building pressure.
However, no signal passed to it.
I believe with 993 fuel pump should run once final stage of ignition closed, the later should close once ECU sees signal form crank position sensor

My suspect is the crank sensor not getting powered by the ECU through terminals 48-49. I just needs to confirm it. Only 1.2 v available at positive terminal. Any ideas??

Check here; https://rennlist.com/forums/993-forum-58/

[TorqueHead]

In post #1 you said "Fuel pump not starting"

I am confused because now you say "fuel pump is fine". Can you explain please?

[mysocal911]

Originally Posted by TorqueHead

In post #1 you said "Fuel pump not starting"

I am confused because now you say "fuel pump is fine". Can you explain please?

He's indicating that the fuel pump runs when the DME relay is bypassed, but that the DME ECU doesn't activate the relay.

[Om85an]

Originally Posted by mysocal911

He's indicating that the fuel pump runs when the DME relay is bypassed, but that the DME ECU doesn't activate the relay.

Absolutely right, Dave

Only once bypassed at the DME relay we can check it ( we provide ground to its terminal) that ground is missing due to second ignition stage not closed which as I said early requires an RPM signal from crank sensor which we dont have it.

Still asking the same question: we need to confirm the ECU output to the crank sensor terminal 48 at ECU how much it should be.

[mysocal911]

Originally Posted by Om85an

Absolutely right, Dave

Only once bypassed at the DME relay we can check it ( we provide ground to its terminal) that ground is missing due to second ignition stage not closed which as I said early requires an RPM signal from crank sensor which we dont have it.

Still asking the same question: we need to confirm the ECU output to the crank sensor terminal 48 at ECU how much it should be.

There is NO output to the crank sensor! Pin 48 is the magnetic RPM sensor input. You need to check it with a voltmeter or an oscilloscope (>.30 Vac).

Again, try here; https://rennlist.com/forums/993-forum-58/

[Om85an]

As Dave said its pin48, we got signal 2-3 VAC.
Now we get power to Fuel pump and pressure is pair enough.
It was the crank sensor gap it should be correctly gapped.

Unfortunately the car still didnt run. We got spark but it seems weak
And we noticed the fuel pump only getting 9 V rather than 12.5 V.

Anybody knows the cause. Can it be lose ground or the ignition timing is off

[TorqueHead]

Thanks for the clarification Dave. It all makes sense now.

BTW, do you mean >3.0 VAC instead of 0.3 volts?

[mysocal911]

Originally Posted by TorqueHead

Thanks for the clarification Dave. It all makes sense now.

BTW, do you mean >3.0 VAC instead of 0.3 volts?

Not really. It's a function of RPM! The post stated, "> .30 Vac "

[Marine Blue]

I’ll throw this out there, I’ve heard of new DME’s DOA so might be worth confirming if the new one is functioning correctly.