Booster Issue

TS87FC3S · 04-30-2010, 11:10 PM

so heres my issue my idle seems fine now except when i hit the brakes it drops lightly if i pump the brakes the car tries to die, is there any weird way of testing booster.. i tried pulling vaccum (vaccum pump) and it wouldnt even build 1 in/hg. But i cant hear where its leaking and brakes feel great.

Kentetsu · 05-01-2010, 11:15 AM

Sounds like a blown diaphragm in the booster, but before jumping to that conclusion I would take a good look at the check valve in the vacuum line.

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TS87FC3S · 05-01-2010, 02:47 PM

i replaced the rusted metal line with a rubber line so i dont have the check valve, i dont think.

Kentetsu · 05-03-2010, 09:05 AM

The check valve should be inline in the rubber hose (at least on 1st gens). If you don't have a check valve, then whenever you go above idle and lose manifold vacuum your booster will also lose it's vacuum.

Max777 · 05-03-2010, 11:34 AM

....and you can also damage the diaphragm under boost, or so I've been told.

04-30-2010, 11:10 PM	#1
TS87FC3S Ask Me About My WANKEL!!! Join Date: Jan 2010 Location: Missouri Posts: 127 Rep Power: 16	Booster Issue so heres my issue my idle seems fine now except when i hit the brakes it drops lightly if i pump the brakes the car tries to die, is there any weird way of testing booster.. i tried pulling vaccum (vaccum pump) and it wouldnt even build 1 in/hg. But i cant hear where its leaking and brakes feel great. __________________ 1984 Rx7 Gs - stripped interior re speed coil overs, tokico blues, re speed crossmemeber and mustang rack, diamond star racing wheels 1988 Rx7 Se - Sold 1988 Rx7 GXL - Sold

05-01-2010, 11:15 AM	#2
Kentetsu RCC Contributor Join Date: Feb 2008 Location: Grand Rapids, Michigan Posts: 530 Rep Power: 18	Sounds like a blown diaphragm in the booster, but before jumping to that conclusion I would take a good look at the check valve in the vacuum line. . __________________ "Learn from the past, or it will become your future...." '85 GS 12a + LSD/Sterling carb/Respeed coilovers/Respeed front swaybar/Respeed adj. rear spring perches/Illuminas/Bilsteins on rear AutoX vids @ http://www.youtube.com/user/Kentetsu1

05-01-2010, 02:47 PM	#3
TS87FC3S Ask Me About My WANKEL!!! Join Date: Jan 2010 Location: Missouri Posts: 127 Rep Power: 16	i replaced the rusted metal line with a rubber line so i dont have the check valve, i dont think. __________________ 1984 Rx7 Gs - stripped interior re speed coil overs, tokico blues, re speed crossmemeber and mustang rack, diamond star racing wheels 1988 Rx7 Se - Sold 1988 Rx7 GXL - Sold

05-03-2010, 11:34 AM	#5
Max777 Pirate Join Date: Mar 2008 Location: Central IL Posts: 1,323 Rep Power: 19	....and you can also damage the diaphragm under boost, or so I've been told. __________________ Rotaries:They are NOT that complicated!

05-03-2010, 09:05 AM	#4
Kentetsu RCC Contributor Join Date: Feb 2008 Location: Grand Rapids, Michigan Posts: 530 Rep Power: 18	The check valve should be inline in the rubber hose (at least on 1st gens). If you don't have a check valve, then whenever you go above idle and lose manifold vacuum your booster will also lose it's vacuum.