Need CIS Bleeding Advice - Please
 

From what I have read to bleed the CIS fuel injection system:
1. turn on the ignition
2. lift the air flow sensor in the air box

Does the relay need to be jumpered when performing this procedure?
When the air flow sensor is lifted, fuel cannot be heard. What could be the cause of this?

Thanks

yes you have to jump at the round relay. I think procedure is in the bently if you have it.

Thanks!

pchinen: you got it right -- you do NOT have to jumper the relay to do what you want to do.

Just for my information: why do you perform a fuel bleeding? Do you simply unplug the injectors and let the fuel goes out?

Thank you.

When you change the filter or accumulator you need to bleed the line. I have always done this by turning on the key (not cranking just on), taking out the air filter, and lifting the air flow sensor in the top of the air box.

You should be able to hear the injectors 'sing' as they bleed.

Thanks everyone for your advice. On my 1974 911 the injectors only sing while bleeding if the relay is jumpered. If the relay is not jumpered, there is no fuel from the injectors. Is this functioning as normal or is my problem more electrical related?

Fuel Pump Relay Wiring....
 

pchinen,

'74 & '75 (911) US models wiring diagrams do not show any fuel pump relay. The fuel pumps ('74 & '75) will run when the ignition switch is turned to ON position. FP relays application started from 1976 to '83SC. I'm interested to know why you supposedly have a FP relay when the car is a '74 model. Are you sure your car have a FP relay? Keep us posted. Thanks.

Tony

Dont over blled it or it will flood and potentially hydrolock. Only do it for a few seconds