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964 Turbo brake booster dont work

Hi my 964 Turbo -91 has been still in the garage for many years.
Now when i start using it the brake booster pump dont work so pedal is firm.

if i conect pin 1 and 4 at presure switch the booster pump is running.
could it be internal problem in the presure sensor? or any tip what i should check up?

Old 08-14-2018, 11:43 PM
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For starters if the car has sat for many years don't start it.

I would flush the brake system with new fluid and drain the fuel tank fill with fresh gas, change the oil and pray. Pull the fuel pump fusses and crank engine until pressure starts to rise before starting after flushing teh fluids.

The brake booster could be many things. If the pump does not start when the key is turned it could be the ignition switch. Once the pump is engaged it should pressurize the bomb in about a minute or less more than a minute and a half it probably needs a new pressure switch.

I would also verify how old the tires are. Porsche recommends replacing after 6 years if they are older I wouldn't drive it. These cars can hurt you with bad tires.

Sorry I can't be of more help but I wouldn't expect to start and drive it after sitting for so long.
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Old 08-15-2018, 05:16 AM
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Quote:
Originally Posted by Cobalt View Post
For starters if the car has sat for many years don't start it.

I would flush the brake system with new fluid and drain the fuel tank fill with fresh gas, change the oil and pray. Pull the fuel pump fusses and crank engine until pressure starts to rise before starting after flushing teh fluids.

The brake booster could be many things. If the pump does not start when the key is turned it could be the ignition switch. Once the pump is engaged it should pressurize the bomb in about a minute or less more than a minute and a half it probably needs a new pressure switch.

I would also verify how old the tires are. Porsche recommends replacing after 6 years if they are older I wouldn't drive it. These cars can hurt you with bad tires.

Sorry I can't be of more help but I wouldn't expect to start and drive it after sitting for so long.
thanks for the tips but no problem barake fluid new, engien rebuild and much more

The pump is not starting when ignition on as it did before.
Old 08-15-2018, 05:58 AM
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Help 1995/993

Does anyone have a clear photo of the passenger door post decal (1995 993).

I would like to see one.
Old 09-05-2018, 01:42 PM
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1989-98 Porsche 911, 964, 993 Turbo ABS Brake Pump 96435505352
Old 09-06-2018, 06:36 AM
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Do you get any brake warning lights( warning buzzer) when you turn on the ignition ? If you start and run the engine? Do get any when you get the pump running bypassing the pressure switch?
Old 09-06-2018, 08:57 AM
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It could be that the pressure switch has stuck/seized in the "maximum pressure" position. This would "fool" the system, no warning lights despite pump not running at all. I believe the switch can be removed from the pump and tested. Could be worth checking/ cleaning all contacts in the pump.
Old 09-06-2018, 09:23 AM
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