Rough start up
05-14-2015, 06:31 PM
#1
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Rough start up
1985 928s U.S.
Rough start up when cold.
Starts and then RPMs struggle then eventually dies. Start again and runs fine.
Vacuum leak? Or a sensor issue? Suggestions would be appreciated!
Rough start up when cold.
Starts and then RPMs struggle then eventually dies. Start again and runs fine.
Vacuum leak? Or a sensor issue? Suggestions would be appreciated!
05-14-2015, 06:37 PM
#2
could be a bad IAC valve. might be sticking open. check fuel dampener vacuum connections as well. also, try turning on the ignition and waiting a second before you start. could be taking it a while to build up enough pressure.
05-15-2015, 12:26 AM
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Turned the key to on.
Let the fuel pump run awhile.
Turn key off then back on.
Let the pump run awhile.
Started fine.
Fuel pump going bad?
Patience needs elongated?
Just one attempt at playing with it as I didn't have much time. Will mess with it more later. Thanks.
Let the fuel pump run awhile.
Turn key off then back on.
Let the pump run awhile.
Started fine.
Fuel pump going bad?
Patience needs elongated?
Just one attempt at playing with it as I didn't have much time. Will mess with it more later. Thanks.
05-15-2015, 12:57 AM
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Can that be replaced without replacing fuel pump?
Or would it be easier to add an additional check valve down the line somewhere? And if so would it matter where it is placed? As in the volume of fuel in a given side of the check valve.
05-15-2015, 01:06 AM
#6
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Yes, the check valve can be replaced without replacing the fuel pump. No, it would not be easier to add an additional check valve.
Did this car sit for a while? Running the pump for a time may have moved all the varnish around in the system. Your injectors may have been gummed up also. If it has been sitting for a while, add some fuel system cleaner (techroline et.al) and drive your car. It will probably be surprising to you how much that helps wake up the car as everything moves and lubricates and cleans itself.
05-15-2015, 08:47 AM
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Preston,
Yes, the check valve can be replaced without replacing the fuel pump. No, it would not be easier to add an additional check valve.
Did this car sit for a while? Running the pump for a time may have moved all the varnish around in the system. Your injectors may have been gummed up also. If it has been sitting for a while, add some fuel system cleaner (techroline et.al) and drive your car. It will probably be surprising to you how much that helps wake up the car as everything moves and lubricates and cleans itself.
Yes, the check valve can be replaced without replacing the fuel pump. No, it would not be easier to add an additional check valve.
Did this car sit for a while? Running the pump for a time may have moved all the varnish around in the system. Your injectors may have been gummed up also. If it has been sitting for a while, add some fuel system cleaner (techroline et.al) and drive your car. It will probably be surprising to you how much that helps wake up the car as everything moves and lubricates and cleans itself.
The car did not sit for a while. The PO drove and I drive it regularly. I will try the additive anyways! I've been meaning to. Thanks!
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05-15-2015, 09:47 AM
#8
Team Owner
once you notice a hard start issue, and a fuel treatment sequence is tried,
Includes adding Techron 1 bottle,
MMO = 6oz.
Startron 1.5 oz. to the fuel
and no improvement noted ,
Then swapping in a new check valve should be tried ,
you also need 3 new sealing rings.
NOTE order the short hard line as well.
NOTE RnR of the capnut could result in crushing the line so it wont seal
If this doesnt cure it then fuel injectors should be swapped out for cleaning or replacement.
If the filter is older than 10 years then a filter is also a good idea
Includes adding Techron 1 bottle,
MMO = 6oz.
Startron 1.5 oz. to the fuel
and no improvement noted ,
Then swapping in a new check valve should be tried ,
you also need 3 new sealing rings.
NOTE order the short hard line as well.
NOTE RnR of the capnut could result in crushing the line so it wont seal
If this doesnt cure it then fuel injectors should be swapped out for cleaning or replacement.
If the filter is older than 10 years then a filter is also a good idea
05-15-2015, 11:15 AM
#9
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once you notice a hard start issue, and a fuel treatment sequence is tried,
Includes adding Techron 1 bottle,
MMO = 6oz.
Startron 1.5 oz. to the fuel
and no improvement noted ,
Then swapping in a new check valve should be tried ,
you also need 3 new sealing rings.
NOTE order the short hard line as well.
NOTE RnR of the capnut could result in crushing the line so it wont seal
If this doesnt cure it then fuel injectors should be swapped out for cleaning or replacement.
If the filter is older than 10 years then a filter is also a good idea
Includes adding Techron 1 bottle,
MMO = 6oz.
Startron 1.5 oz. to the fuel
and no improvement noted ,
Then swapping in a new check valve should be tried ,
you also need 3 new sealing rings.
NOTE order the short hard line as well.
NOTE RnR of the capnut could result in crushing the line so it wont seal
If this doesnt cure it then fuel injectors should be swapped out for cleaning or replacement.
If the filter is older than 10 years then a filter is also a good idea
The fuel treatment you speak of. Do I add that separately or with the same tank? (All at once)
Thanks.