No start 928
#16
Supercharged
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Go to 928GT.com and print out the fuel and relay chart for the car.
I agree with Sean that it could be a bad LH. However, the only thing that I know will cut the fuel pump and the injectors is a bad Crank position sensor. Sometime the connectors can be gnarly and you can accidentally plug them in backwards.
But there are three other relays to check before digging into that stuff again.
These can all be swapped with the horn relay to verify they are working.
Ignition Relay - X
LH Relay - XXV
Fuel Pump Relay - XXVI
One other possibility is the Kick-down relay (if the car is an automatic) can interupt the injector pulse but wouldn't affect the fuel pump - XVII
I agree with Sean that it could be a bad LH. However, the only thing that I know will cut the fuel pump and the injectors is a bad Crank position sensor. Sometime the connectors can be gnarly and you can accidentally plug them in backwards.
But there are three other relays to check before digging into that stuff again.
These can all be swapped with the horn relay to verify they are working.
Ignition Relay - X
LH Relay - XXV
Fuel Pump Relay - XXVI
One other possibility is the Kick-down relay (if the car is an automatic) can interupt the injector pulse but wouldn't affect the fuel pump - XVII
#17
Team Owner
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you need to verify that you have the crank position sender wires correctly connected,
could they be swapped with either one of the knock sensors or the TPS sensor.
Do the relay swap after verifying the connectors
could they be swapped with either one of the knock sensors or the TPS sensor.
Do the relay swap after verifying the connectors
Last edited by Mrmerlin; 09-08-2010 at 12:54 PM.
#20
Team Owner
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CPS turns on the LH and EZK.
if its not connected to the correct plug the car wont run.
Also if the tach, isnt getting a signal from the CE panel the car wont run
Verify connectors then replace.......the relays listed, ... one at a time,
then try to start after each swap out, (this will isolate the bad relay)
XXVI LH jet Fuel injection # 53 Then
XXI Ignition System its a (# 53 with a fuse tester) Then
XX Fuel pump # 53 Then
X Ignition relay # 53,,
note PN for the #53 relay is 141.951.253.B
you can use the horn relay to verify if the relay position is working, its a #53
Smell the old relays for burning or melted solder joints where the pins come out of the bottom of the relays,
any corroded pins or burned relays should be opened.
MAKE sure to also replace the fuel pump fuse
See if the tach is jumping when you crank??
yes then the CPS is working though the signal may be weak.
Fuse relay chart here.
https://www.928gt.com/skin2.htm
if its not connected to the correct plug the car wont run.
Also if the tach, isnt getting a signal from the CE panel the car wont run
Verify connectors then replace.......the relays listed, ... one at a time,
then try to start after each swap out, (this will isolate the bad relay)
XXVI LH jet Fuel injection # 53 Then
XXI Ignition System its a (# 53 with a fuse tester) Then
XX Fuel pump # 53 Then
X Ignition relay # 53,,
note PN for the #53 relay is 141.951.253.B
you can use the horn relay to verify if the relay position is working, its a #53
Smell the old relays for burning or melted solder joints where the pins come out of the bottom of the relays,
any corroded pins or burned relays should be opened.
MAKE sure to also replace the fuel pump fuse
See if the tach is jumping when you crank??
yes then the CPS is working though the signal may be weak.
Fuse relay chart here.
https://www.928gt.com/skin2.htm
Last edited by Mrmerlin; 09-08-2010 at 06:15 PM.
#21
Rennlist Member
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Use Andrew's info and also this - http://www.jdsporsche.com/fault%20find.html
CPS feeds engine rpm to EZK, you should have spark if EZK relay and EZK are good. If you have spark, then tach should flicker when you crank the engine.
EZK feeds modified engine rpm info to pin 1 LH ECU. Unless LH gets this signal, it will not energise the Fuel pump relay or fire the injectors.
So if you have 12v rpm signals at pin 1 LH and the LH relay is good, there is the possibility of a dead LH ECU.
CPS feeds engine rpm to EZK, you should have spark if EZK relay and EZK are good. If you have spark, then tach should flicker when you crank the engine.
EZK feeds modified engine rpm info to pin 1 LH ECU. Unless LH gets this signal, it will not energise the Fuel pump relay or fire the injectors.
So if you have 12v rpm signals at pin 1 LH and the LH relay is good, there is the possibility of a dead LH ECU.
#22
Team Owner
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nice link John