What is the CIS fuel pump pressure for a '76 911?

[billh1963]

Good morning,
What is the fuel pump pressure for a 1976 911 with CIS? The replacement pump can be set for 3.0 bar or 6.5 bar and I don't know which setting is correct.

The documentation I see online shows test pressures of mid 3's at high idle. Will the 3.0 be sufficient or do I need the 6.5 to deliver the full pressure?

[boyt911sc]

Originally Posted by billh1963

Good morning,
What is the fuel pump pressure for a 1976 911 with CIS? The replacement pump can be set for 3.0 bar or 6.5 bar and I don't know which setting is correct.

The documentation I see online shows test pressures of mid 3's at high idle. Will the 3.0 be sufficient or do I need the 6.5 to deliver the full pressure?

Bill,

There is no such thing as 'fuel pump pressure for a 1976 911 with CIS'. Nor the replacement pumps can bet set to a specific pressure. The FP is rated by its delivery (volumetric flow per unit time). For example, you would need a FP for a '76 with a delivery (capacity) of 2 liters (minimum) per minute. So if you use a FP for your car with only 1.0 liter per minute (flow rate), it would not be able to deliver the needed fuel. And the recorded fuel pressure would be too low.

There are three (3) critical CIS components you have to consider to get the correct fuel pressures (control and system) and they are:
Fuel pump
Warm up regulator
Fuel distributor


Tony

[prschmn]

6.5 bar would be a 930 pump. sc cis runs at 4.5 bar
Don't know what pump you found that's adjustable.
Fuel pressure is controlled by a valve in the fuel distributor.

[75 911s]

He has the Pierburg. It comes with extra fittings for other applications.
The three fittings are not used. Simply remove the banjo connector off the original pump and it should thread into the top (by the electrical connections)

Mine is missing the boots on the connections. I'll be putting those on today.