1999 996 Carrera Cabriolet, no fuel preasure

[jack hulne]

I have been fighting this for to long so hoping somebody may have an idea, thanks in advance for any and all input.

My 1999 996 stopped when I pulled into a store, it wouldn't re-start right away and it drained the battery very quickly so I put in a new battery and the car started and drove home fine. Next weekend took the car out again and it died again after about 20 minutes, would not re-start and to date has not. Checked several sites all pointed to fuel pump so I replaced the fuel pump, next fuel pump relay still no fuel pump run? Crank position switch, replaced, cam position replaced. By now I have become frustrated and starting to second guess myself. When I jump the fuel relay I can here the fuel pump start but do not get any fuel pump when I turn the key on. I can spray starting fluid and engine starts so I have compression and spark. 

[JFP in PA]

35 minutes ago, jack hulne said:

I have been fighting this for to long so hoping somebody may have an idea, thanks in advance for any and all input.

My 1999 996 stopped when I pulled into a store, it wouldn't re-start right away and it drained the battery very quickly so I put in a new battery and the car started and drove home fine. Next weekend took the car out again and it died again after about 20 minutes, would not re-start and to date has not. Checked several sites all pointed to fuel pump so I replaced the fuel pump, next fuel pump relay still no fuel pump run? Crank position switch, replaced, cam position replaced. By now I have become frustrated and starting to second guess myself. When I jump the fuel relay I can here the fuel pump start but do not get any fuel pump when I turn the key on. I can spray starting fluid and engine starts so I have compression and spark. 

 

Welcome to RennTech 

 

Have you checked the actual fuel pressure?  You also have not mentioned the fuel filter or the fuel pressure regulator, both of which could be part of the equation. 

 

I would also be looking at the ignition switch electrical section, a known weak point that causes all sorts of electrical issues when it goes bad.

 

Good luck.

[DBJoe996]

42 minutes ago, JFP in PA said:

I would also be looking at the ignition switch electrical section, a known weak point that causes all sorts of electrical issues when it goes bad.

This!

[jack hulne]

No fuel pressure in the engine compartment as I get no fuel pump run. One question I have, is the fuel pressure regulator controlled by the FRC that some have mentioned located on the relay tray in the rear and if so does it also control power to the fuel relay under the dash? If it switch issue can you replace just the mechanical switch or do I have to have the key reader, ECM and Immobilizer?

[JFP in PA]

1 minute ago, jack hulne said:

No fuel pressure in the engine compartment as I get no fuel pump run. One question I have, is the fuel pressure regulator controlled by the FRC that some have mentioned located on the relay tray in the rear and if so does it also control power to the fuel relay under the dash? If it switch issue can you replace just the mechanical switch or do I have to have the key reader, ECM and Immobilizer?

 

No, it is located on the fuel rail and is a mechanical device.

 

The ignition switch is a cheap  electrical part of the key assembly that requires no programing to replace.  It is a pain to access, but controls ALL electrical functions in the car:

 

 

A DIY how to here: How to change 996 ignition switch electrical section

 

Be sure to buy the factory part, aftermarket versions are notoriously bad..............

[jack hulne]

Thanks! Switch has been ordered and will update when I have it in.

[JFP in PA]

35 minutes ago, jack hulne said:

Thanks! Switch has been ordered and will update when I have it in.

 

These switches are a common electrical fault source in these cars; fortunately they are not expensive and are a common DIY project.

[mdreef]

On 9/14/2020 at 12:56 PM, jack hulne said:

Thanks! Switch has been ordered and will update when I have it in.

Hello Jack and everyone else,

 

I'm in the same exact position with my 2001 996 Cabriolet and I'm getting desperate. The problem started when I got a CEL indicating no voltage at Bank 1 post cat o2 sensor. I replaced it, and since then, I haven't been able to get the car to fire. It started for about 2 seconds and died. It all seems too coincidental.

 

I thought I might as well replace parts, as I have 150k miles on the clock. I have replaced the following:

• Fuel Pump
• Fuel Pump Relay
• Fuel Filter
• Ignition Switch
• Crankshaft Position Sensor
• Battery
• Bank 1 post cat o2 sensor

 

The MAF has about 30k miles on it. I disconnected it to replace the o2 sensor and I thought maybe the harness got damaged, but I read that unplugging the MAF would put the DME in a default program, so I don't believe that's it.

 

The fuses are all good. I tested for spark and confirmed spark. I can hear the fuel pump running when I jump the relay. The car cranks well but no fire.

I have an Autel 2-way computer, and when I ran an active test of the fuel pump relay, I got a message stating "no voltage" so the test failed.  That leads me to believe that something is keeping the pump from coming on, confirmed by the fact that I don't hear the pump running when I try to start the car.

 

What could be causing a no voltage situation at the fuel pump relay when there's voltage when jumped? 

Jack, did you ever figure out your problem? Has anyone else run into this situation and/or have any advice?

 

Thanks in advance!

 

Edited February 23 by mdreef