Fuel Pump Diagnosis

[GaryDG]

I am just beginning to go through the process of getting my 83 911 running again as it has been in storage for the last 1 1/2 years.

I was emptying the fuel tank by connecting a long hose to the fuel filter intake hose, and noticed the fuel flow didn't seem a strong as another time I did this.

The 911 101 book says that if the fuel pump stays on for an extended period of time on when the fuel tank is empty (this is what I believe happened the last time I started it and let it idle until I think it ran out of fuel) there is the strong possibility that the pump might fail.

I have been unable to find a thread recommending which fuel pressure gauge to purchase to confirm my pump is putting out fuel at the correct pressure.

Also where would be the appropriate place to test the pressure?

Any recommendations on which to get?

[boyt911sc]

Gary,

Since you don't have a pressure gauge at the moment, you could check the condition of your FP by measuring the volumetric low rate (liter per min.). Do you know how to run the FP by jumpering terminals #87a & 30 (FP relay socket)? With the ignition SW @ ON position (not start) and the 2 terminals are bridged, the FP will run. Measure the fuel delivery before the fuel accumulator. A measured volume of 1 liter per 30 sec. or 2 liters per min. (approx.) indicates good pump. And if you have a pressure gauge handy, a minimum of 90 psi. is required for your CIS. Keep us posted.

Tony

[GaryDG]

Where should the pressure readings be taken? Before the accumulator?

What would be a good pressure tester to buy?

[GaryDG]

I didn't time the flow as I emptied the tank from the hose from the accumulator but it was substantially less than 1litre/30secs. If I took it from before the accumulator I guess based on your suggestion it might be a higher flow.

Where should the pressure readings be taken? Before the accumulator?

What would be a good pressure tester to buy?

[timmy2]

Our host sells a CIS pressure tester.

[E Sully]

You should spend the money and buy the CIS set up. Then you can make sure the system and control pressure are set correctly. Read this link.
CIS Primer for the Porsche 911

[Bob Kontak]

Originally Posted by timmy2

Our host sells a CIS pressure tester.

+1

Go with the PP set. Harbor freight sells a set a few dollars cheaper but many posts say the pelican set is nicer quality.

Pelican Parts - Product Information: TOL-TA33865