csi Fuel problem

[Bassethound]

My car for 12years 1977 2.7 911

Hi all,heres a good one for all you brainboxes out there.

1. Turn Key Pump runs, no pressure build up.No start.

2. Connect test gauge setup to line from FD to WUR
turn key,Pump runs,pressure builds up after 10 secs.
Engine starts

3. Remove gauge .Engine starts

4. leave overnight.

5. Same problem ,same procedure.engine starts.

If it helps there is zero residual pressure as soon as the pump stops.

I am starting to wear a groove in my head through scratching it so much
any ideas. Anybody ??
PS It has a new pump and check valve.

[jess p]

Sorry it’s Cis

This is the 914 forum but that’s ok. I have a 76 911s so maybe I can help you.

Are you using a Bosch tester? It sounds like you have a bad WUR.

You should have at least 66psi to the WUR.

Some things to consider, check your fuel filter. I doubt it’s the one way check valve or the fuel accumulator. With the key in the on position do you hear the fuel pump run when you lift the sensor plate of the FD.
1) if you can replace the fuel pump relay
2) check the fuel filter
3) check fuel pressure to the WUR

Reason I say the fuel pump relay is that pin 30 from the fuel pump relay powers the warm up regulator, thermal valve and the auxiliary air regulator.

Additionally, make sure no vacuum leaks from the throttle valve to the thermal valve to the WUR.

The car starts when you bleed off pressure and that leads me to think it’s the WUR. They can be adjusted.

[Dave at Pelican Parts]

You may get more responses in the 911 forum. I will move this thread over there.

--DD

[boyt911sc]

Originally Posted by Dave at Pelican Parts

You may get more responses in the 911 forum. I will move this thread over there.

--DD

Dave,

You have moved this thread several days ago and there is a discussions going on already.This is a redundant thread. Thanks.

Tony