2000 2.7 no start

[Cayden]

I’m having a no start issue, I am 100% certain that it is because the fuel pump isn’t getting a signal too turn on. I know it works because I have jumped the pins on the relay and the pump runs fine. I have also tested the relay itself. The next step I though I’d take was the CPS but the new one doesn’t seem to have solved the problem. What could cause the fuel pump to not be told to turn on?

 

Thanks in advance for any help, it would be greatly appreciated.

Edited April 10, 2023 by Cayden

[map]

What is a CPS when it is fitted to a 986?

[½cwt]

6 hours ago, Cayden said:

I’m having a no start issue, I am 100% certain that it is because the fuel pump isn’t getting a signal too turn on. I know it works because I have jumped the pins on the relay and the pump runs fine. I have also tested the relay itself. The next step I though I’d take was the CPS but the new one doesn’t seem to have solved the problem. What could cause the fuel pump to not be told to turn on?

 

Thanks in advance for any help, it would be greatly appreciated.

@map Crank (or cam) position sensor.

The ignition switches on these can cause strange things to happen when they start to fail.  Is the key popping out easily when you switch off?

[map]

1 hour ago, ½cwt said:

@map Crank (or cam) position sensor.

Thanks. 
 

@Cayden - is the passenger side (assuming Right Hand Drive) underseat area dry/has it ever been flooded?

If the ignition switch is OK - as suggested above - and the rest of the “electrical switches” in the fuel pump circuit are OK I’d be inclined to look at an immobiliser problem/fault - and that stuff is under the passenger seat. 

[½cwt]

14 minutes ago, map said:

Thanks. 
 

@Cayden - is the passenger side (assuming Right Hand Drive) underseat area dry/has it ever been flooded?

If the ignition switch is OK - as suggested above - and the rest of the “electrical switches” in the fuel pump circuit are OK I’d be inclined to look at an immobiliser problem/fault - and that stuff is under the passenger seat. 

Good call. We've had a lot of rain recently and if the drains in the rear have backed up the water comes down the rear bulkhead and floods the floor pan under the seats....

[Cayden]

5 hours ago, map said:

Thanks. 
 

@Cayden - is the passenger side (assuming Right Hand Drive) underseat area dry/has it ever been flooded?

If the ignition switch is OK - as suggested above - and the rest of the “electrical switches” in the fuel pump circuit are OK I’d be inclined to look at an immobiliser problem/fault - and that stuff is under the passenger seat. 
 

Is there a good way to test the immobilizer? I have a multimeter and a waveforms device. I’ll see if I can find the pin layout for the immobilizer.

It’s never been flooded before, but is has gotten damp. I think the ignition switch is fine because the key doesn’t pop out and the car does crank, it just won’t fire because it’s not getting fuel.

Edited April 11, 2023 by Cayden

[map]

19 minutes ago, Cayden said:

It’s never been flooded before, but is has gotten damp. I think the ignition switch is fine because the key doesn’t pop out and the car does crank, it just won’t fire because it’s not getting fuel.

Sounds like an immobiliser problem - especially as the fuel pump runs with a direct supply or when supplied via a direct connection on the relay.  

[Cayden]

22 minutes ago, map said:

Sounds like an immobiliser problem - especially as the fuel pump runs with a direct supply or when supplied via a direct connection on the relay.  

Okay, thank you. I will look for visible corrosion this weekend. Is there a good way to test it? I have a multimeter and waveforms device. The one other thing is, the car cranks fine. Would it be possible for the immobilizer to not allow fuel but allow the car to crank?

[map]

21 minutes ago, Cayden said:

Okay, thank you. I will look for visible corrosion this weekend. Is there a good way to test it? I have a multimeter and waveforms device. The one other thing is, the car cranks fine. Would it be possible for the immobilizer to not allow fuel but allow the car to crank?

Ideally I would see what a code reader can tell you.  I have a Durametric (it's out on loan at the moment) like others and some have the Porsche factory OBD tool.  These two will read all codes (generic and Porsche specific) which might well be the fastest way to find out if there's a problem with the security/immobiliser.

Can't see where you are so let the forum know and there may be someone nearby who would be happy to travel to plug in their reader (the fee is likely to be biscuits and tea) - that way you can see some real information.

In terms of multimeters and the like - they're a closed book to me so I cannot help.

@Richard Hamilton - can you shed any light on the problem @Cayden has?

Thanks

[Nobbie]

If you can get the pump to work by jumping the relay, why not try this while you crank it over with the key? Could eliminate the fuel pump as an issue?

[Cayden]

1 hour ago, map said:

Ideally I would see what a code reader can tell you.  I have a Durametric (it's out on loan at the moment) like others and some have the Porsche factory OBD tool.  These two will read all codes (generic and Porsche specific) which might well be the fastest way to find out if there's a problem with the security/immobiliser.

Can't see where you are so let the forum know and there may be someone nearby who would be happy to travel to plug in their reader (the fee is likely to be biscuits and tea) - that way you can see some real information.

In terms of multimeters and the like - they're a closed book to me so I cannot help.

@Richard Hamilton - can you shed any light on the problem @Cayden has?

Thanks

Unfortunately I live in the states, so that fee is more likely to be a cheeseburger and a diet coke. I think I am going to buy myself the most basic durametric option, as I’m sure I’ll need it in the future.

[Cayden]

25 minutes ago, Nobbie said:

If you can get the pump to work by jumping the relay, why not try this while you crank it over with the key? Could eliminate the fuel pump as an issue?

I’ve been a little concerned of damage trying that, since the pump will be stuck on until the battery is disconnected.

[½cwt]

3 hours ago, Cayden said:

It’s never been flooded before, but is has gotten damp. I think the ignition switch is fine because the key doesn’t pop out and the car does crank, it just won’t fire because it’s not getting fuel.

The key and barrel should pop out a little when you switch it back to the off position.

[charlieboy2608]

A bit late to the party but am I correct in thinking a 2000 MY 986 has a fuel filter under the car which might also contribute to this issue if its blocked.......quick to check and at no cost.

[½cwt]

3 hours ago, charlieboy2608 said:

A bit late to the party but am I correct in thinking a 2000 MY 986 has a fuel filter under the car which might also contribute to this issue if its blocked.......quick to check and at no cost.

Up to 2001 model year there is an inline fuel filter under the car.

[Richard Hamilton]

I would definitely see if there are any fault codes.

The immobiliser inhibits cranking, fuel supply, and ignition.  If it cranks, it doesn't sound like an immobiliser problem.  Not sure how you tested it, but I think I would be tempted to swap the fuel pump relay.