More on the Won't start Saga
11-05-2017, 04:16 PM
#1
More on the Won't start Saga
She (it's the "MAN" when it is running but a "Bitch" at present) after my last bout of not starting... she has been starting & running fine...I decided to go ahead & clean ground points & replace relays...started & ran fine before & afterwards up to yesterday ...got in it this am & cranked but no run...I checked & is getting spark...any suggestions as to where I should look....??
thanks
Tom Taylor
thanks
Tom Taylor
11-05-2017, 05:32 PM
#2
Chronic Tool Dropper
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Hi Tom --
Help us out... What year is your car?
Help us out... What year is your car?
11-05-2017, 06:45 PM
#3
Team Owner
well without any other info i would say go to the CE panel and re verify the work you did to the relays and fuses.
Maybe you have a blown fuel pump fuse or have a relay in the wrong position.
Dr Bob is right need more info for a more complete diagnosis.
you could put a spray of ether into the intake and crank it ,
if it fires then you are looking for fuel.
Maybe you have a blown fuel pump fuse or have a relay in the wrong position.
Dr Bob is right need more info for a more complete diagnosis.
you could put a spray of ether into the intake and crank it ,
if it fires then you are looking for fuel.
11-05-2017, 07:24 PM
#4
I do apologize 87 928 s4 5spd....I cannot believe it is in the relays or ground pts as it ran fine before & after I replaced the relays...it sat overnite & today would not start at all but I was getting fire.
11-05-2017, 07:37 PM
#5
Team Owner
pull the vacuum lines off the front damper and the rear FPR right side rear fuel rail,
smell for gas in the lines.
If you smell fuel hold the pedal to the floor and crank it till it starts.
I will repeat myself.
I would go to the CE panel and re verify the work you did to the relays and fuses.
Maybe you have a blown fuel pump fuse or have a relay in the wrong position.
Take your time checking the fuses and correct relay positions,
even better let someone else check your work.
Its easier to find a relay in the wrong position if you have not talked yourself into the fact that everything is correct.
Thats why its so easy for savvy buyers to have a new to them 928 running in 15 mins or less after charging the battery and sorting out the CE panel.
smell for gas in the lines.
If you smell fuel hold the pedal to the floor and crank it till it starts.
I will repeat myself.
I would go to the CE panel and re verify the work you did to the relays and fuses.
Maybe you have a blown fuel pump fuse or have a relay in the wrong position.
Take your time checking the fuses and correct relay positions,
even better let someone else check your work.
Its easier to find a relay in the wrong position if you have not talked yourself into the fact that everything is correct.
Thats why its so easy for savvy buyers to have a new to them 928 running in 15 mins or less after charging the battery and sorting out the CE panel.
11-05-2017, 10:27 PM
#6
Rennlist Member
Tom,
I just got one of these, '87 S4 5 speed, running for a sort of local guy to me. After I did my diagnosis, it started in 15 minutes.
I'm not convinced your issue is the same.
A great rule is to go back to the last thing that you did and double check.
I think your issue may be a electrical issue keeping the LH from turning on or the Fuel pump from running.
You said that you cleaned ground points and replaced relays. Did you also do anything with the fuses?
Did your weather change, a temperature change overnight.
A ground that came loose or a poor contact on a relay or fuse could be affected by a temperature change or vibration.
I hope that is all that it is.
Ken
'89 928 GT
I just got one of these, '87 S4 5 speed, running for a sort of local guy to me. After I did my diagnosis, it started in 15 minutes.
I'm not convinced your issue is the same.
A great rule is to go back to the last thing that you did and double check.
I think your issue may be a electrical issue keeping the LH from turning on or the Fuel pump from running.
You said that you cleaned ground points and replaced relays. Did you also do anything with the fuses?
Did your weather change, a temperature change overnight.
A ground that came loose or a poor contact on a relay or fuse could be affected by a temperature change or vibration.
I hope that is all that it is.
Ken
'89 928 GT
Last edited by Ken P; 11-06-2017 at 12:21 PM. Reason: correctioin
11-06-2017, 12:03 PM
#7
Ken...I did not touch the fuses...haven't gotten back to it to recheck relays...the thing bugging me is that when I completed the relay replacement...it started on first crank every time & then the following day it won't ...really haven't had a temp change but have been rainy...it stays garaged & not out in the weather...I am going back over it today & "lick my calf again"!!
Thanks to all for your advice...
Tom Taylor
Thanks to all for your advice...
Tom Taylor
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11-06-2017, 12:07 PM
#8
Burning Brakes
A similar thing happened to my 91. It ended up being the brains. I sent it off to get rebuilt and everything works great now.
11-06-2017, 12:38 PM
#9
Chronic Tool Dropper
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Tom --
Do a little searching on the subject of LH brain failure. This is the fuel injection controller that lives in the passenger footwell behind that cover on the right side. They fail with age, and the failures are often instant. If the controller has not yet been rebuilt with a new "tile", it's a ticking time bomb. Our regular suppliers offer rebuild services.
Follow Mrmerlin's guidance on checking the CE panel. The connectors in that panel for the relays are pretty stiff, as you found out while replacing relays. Sometimes a connector gets pushed back into the plastic socket when you are replacing relays, so there isn't a full connection. Lift the ground strap at the rear apron behind the tool panel to isolate the battery, then carefully unbolt the CE panel. From the rear, make sure that all the connectors under the relays you replaced are still fully inserted into the holders.
Other general guidance: The three critical engine system relays (fuel pump, ignition, injection) plus the cooling fans each has a dedicated power supply wire from the battery positive post clamp. Those connections must be clean and the nut that holds them together needs to be tight. Look for the smaller red wires at the battery clamp, as they easily get loosened accidentally while servicing the battery. Plus they are often exposed to corrosive fumes if the battery isn't correctly vented outside the battery well. I clean them with a brass detailer's toothbrush until things are bright again, reassemble the terminal eyes and snug the nut. Then a thin coating of Vaseline helps keep the battery vapors away.
Except for the LH failure, the diagnostic procedures for no-start follow a common protocol. Check for spark, check for fuel pump run while cranking, check for fuel pressure, check for injectors firing correctly, check for compression. Maybe look at the timing belt first though, especially if at any time in the restart processes the engine backfired. Pull the passenger side cam belt cover, hand rotate the engine to verify that the timing mark on the gear lines up with the mark on the cover when the engine is at top center on #1 cylinder. This takes 10 minutes or so, and may avoid some valve damage if the belt jumped time when the engine turned backwards during a backfire event. It's a cheap insurance check.
Post what you find and the crowd will offer next steps.
Do a little searching on the subject of LH brain failure. This is the fuel injection controller that lives in the passenger footwell behind that cover on the right side. They fail with age, and the failures are often instant. If the controller has not yet been rebuilt with a new "tile", it's a ticking time bomb. Our regular suppliers offer rebuild services.
Follow Mrmerlin's guidance on checking the CE panel. The connectors in that panel for the relays are pretty stiff, as you found out while replacing relays. Sometimes a connector gets pushed back into the plastic socket when you are replacing relays, so there isn't a full connection. Lift the ground strap at the rear apron behind the tool panel to isolate the battery, then carefully unbolt the CE panel. From the rear, make sure that all the connectors under the relays you replaced are still fully inserted into the holders.
Other general guidance: The three critical engine system relays (fuel pump, ignition, injection) plus the cooling fans each has a dedicated power supply wire from the battery positive post clamp. Those connections must be clean and the nut that holds them together needs to be tight. Look for the smaller red wires at the battery clamp, as they easily get loosened accidentally while servicing the battery. Plus they are often exposed to corrosive fumes if the battery isn't correctly vented outside the battery well. I clean them with a brass detailer's toothbrush until things are bright again, reassemble the terminal eyes and snug the nut. Then a thin coating of Vaseline helps keep the battery vapors away.
Except for the LH failure, the diagnostic procedures for no-start follow a common protocol. Check for spark, check for fuel pump run while cranking, check for fuel pressure, check for injectors firing correctly, check for compression. Maybe look at the timing belt first though, especially if at any time in the restart processes the engine backfired. Pull the passenger side cam belt cover, hand rotate the engine to verify that the timing mark on the gear lines up with the mark on the cover when the engine is at top center on #1 cylinder. This takes 10 minutes or so, and may avoid some valve damage if the belt jumped time when the engine turned backwards during a backfire event. It's a cheap insurance check.
Post what you find and the crowd will offer next steps.
11-06-2017, 03:06 PM
#10
I have done a recheck on my relays etc...I jumped (properly! according to the maintenance manual) the fuel pump relay female plug & fuel pump ran...I then unhooked the cross-over fuel line (at front of engine) from the passenger side fuel rai...l cranked the engine & got no fuel....jumped the fuel pump again & got fuel....so something must be preventing the fuel pump from kicking in when I crank it....I am now going to check the back of the CE panel & check the connections I am wondering if the fuel pump relay is getting juice. maybe there is my problem behind the panel....
11-06-2017, 05:44 PM
#12
Removed kick-down relay...no change...why would it ever have been there if that is all it is useful for.... for as mine is 5 spd & why remove it?????? Just wondering..........
11-06-2017, 08:26 PM
#13
Rennlist Member
Tom,
I'm not sure what a "correct" kick down relay would do in that position. But on the other '87 that I just helped with, there was some other type of relay in that spot, not a kick down relay .
What it did, to cause the car to not start, is there is an engine speed signal from the EZK to the LH. This relay is on the electrical path, of that signal. If an incorrect relay is in that socket, it loads down and distorts the engine speed signal to the LH. With this signal incorrect, the LH will not detect that the engine is turning and will not turn on the LH or the Fuel Pump relays.
With a correct relay in that position, a manual transmission car should not have any relay in that position, I assume that the kick down relay senses the increase in engine RPM and energizes the Automatic transmission kick down function.
Someone saw an empty relay socket ans stuffed one in there. Is it the correct relay for that position? I think it is 928.618.108.00.
Ken
I'm not sure what a "correct" kick down relay would do in that position. But on the other '87 that I just helped with, there was some other type of relay in that spot, not a kick down relay .
What it did, to cause the car to not start, is there is an engine speed signal from the EZK to the LH. This relay is on the electrical path, of that signal. If an incorrect relay is in that socket, it loads down and distorts the engine speed signal to the LH. With this signal incorrect, the LH will not detect that the engine is turning and will not turn on the LH or the Fuel Pump relays.
With a correct relay in that position, a manual transmission car should not have any relay in that position, I assume that the kick down relay senses the increase in engine RPM and energizes the Automatic transmission kick down function.
why would it ever have been there
Ken
11-06-2017, 08:27 PM
#14
Chronic Tool Dropper
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When installed in a 5-speed car, the kickdown relay will keep the engine from starting.
The fuel pump relay depends on a signal to close that comes from the LH injection controller via the crank position sensor and the EZK ignition controller. The crank position sensor also feed the tachometer via the EZK, so if you see the tach jumping as you crank, there's a reasonable chance that the crank position sensor is working. Failure modes for that sensor start with wiring and connector deterioration and failure. The sensor itself is under the air cleaner housing on the right side ("right" is right side when sitting in the driver's seat) of the block just forward of the bellhousing split. There's a single Allen-head capscrew that holds the sensor in place, and the wiring comes out the right side over the right fuel rail. Remove the right-side fuel rail cover (two bolts) to expose the wiring and connector for inspection. The connectors disintegrate with age and heat exposure. It's possible to replace the connetcor for the car side of the wiring. By the time the sensor side of the connector fails, the rest of the wire and the sensor itself are due for replacement anyway. If you haven't replaced this critical senor already, now's a good time. There's a long list of other work to do as part of an "intake refresh", none that will keep the engine from starting though.
The fuel pump relay depends on a signal to close that comes from the LH injection controller via the crank position sensor and the EZK ignition controller. The crank position sensor also feed the tachometer via the EZK, so if you see the tach jumping as you crank, there's a reasonable chance that the crank position sensor is working. Failure modes for that sensor start with wiring and connector deterioration and failure. The sensor itself is under the air cleaner housing on the right side ("right" is right side when sitting in the driver's seat) of the block just forward of the bellhousing split. There's a single Allen-head capscrew that holds the sensor in place, and the wiring comes out the right side over the right fuel rail. Remove the right-side fuel rail cover (two bolts) to expose the wiring and connector for inspection. The connectors disintegrate with age and heat exposure. It's possible to replace the connetcor for the car side of the wiring. By the time the sensor side of the connector fails, the rest of the wire and the sensor itself are due for replacement anyway. If you haven't replaced this critical senor already, now's a good time. There's a long list of other work to do as part of an "intake refresh", none that will keep the engine from starting though.