Porsche 944 not sparking/getting fuel

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luke_all@optusnet.com.au - 27 Dec 2007 11:43 GMT

Hi,

I have a 1983 Porsche 944 NA, I am getting no spark.

It was running fine untill its sitting in the carport for 10 years.

I have replaced the DME relay and the DME module.

I have power at the coil, coil has been tested to be working. I am
getting no power out of the middle of the coil/switching power at the
terminals.

I do not have an alarm system.

I will look at the speed and reference sensors but whilst I am
cranking the motor, I can't hear the fuel pump running which makes me
think it's not only the speed or reference sensors I should be looking
at. I have bridged the terminals at the DME relay and the fuel pump
works fine...

Is it normal for the fuel pump not to switch on during cranking if the
speed or reference sensors are faulty?

Does it need an oil pressure reading before sparking?

Thank you for your time

Luke

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William Noble - 28 Dec 2007 03:45 GMT

put a scope on the low side of the coil and see if it is getting triggered.
test continuity of the reference and mark sensors. wiggle the connectors,
I've seen that cause problems. try a spray of starting fluid (ether) , if
there is any spark at all, it will start. What test for "no spark" have you
run - the usual test is to pull the center wire from dist cap and crank
engine - see spark (if no spark, then you are right --- ) - if there is a
spark, pull #1 plug wire from plug, insert a wire or screwdriver into the
end and repeat - if no spark (and there was in prior test), change ignition
wires, rotor and cap.

> Hi,
>
[quoted text clipped - 24 lines]
>
> Luke

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luke_all@optusnet.com.au - 30 Dec 2007 11:04 GMT

Thanks for your response William,
I have tested from the center of the coil and am getting no spark.
I dont have an oscilloscope to check the reference/speed sensor
output. I have checked the resistances and they are in spec. I have
just ordered new speed and reference sensors which should be coming in
a week or so. Hopefully they will fix the sparking problem.
Then i am left with the fuel pump problem!!
With spraying ether/starting fluid (when i do get it sparking), could
that get the fuel pump to switch on...?

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darthpup - 30 Dec 2007 15:31 GMT

I went through a similiar problem with an 84 944. It finally came
down to a bad connection on the back of the relay/fuse panel.
You will need to take out the seat and get underneath the dash. Have
someone turn the ignition while you move the wires around until you
find the problem. These aging 944s all have this problem. The
electrical connectors corrode and stop conducting.

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William Noble - 01 Jan 2008 07:09 GMT

I an deeply dubious that changing the sensors will help - borrow a scope, or
some way to see a 1V (aprox) pulse and see if the pulses are getting to the
computer. Also, did you test that grounding the low side of the spark coil
will in fact produce a spark?

Re fuel pump - wire directly to the pump and see if it works before doing
much else - the usual culprit is a DME relay, they develop a bad solder
connection - cheap fix if you can solder

> Thanks for your response William,
> I have tested from the center of the coil and am getting no spark.
[quoted text clipped - 5 lines]
> With spraying ether/starting fluid (when i do get it sparking), could
> that get the fuel pump to switch on...?

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