VS commodore CAS or Fuel Pump? Fuel pump new BUT not priming on accessories

[robert422]

Hey guys new to the forum, been checking out related posts and I need a few answers to my questions before i go spending a big amount of money. My car stalled on me whilst driving a few times, and i managed to start her back up again, but after a few times it wouldnt start at all. At first (after it had stalled a few times) I change my fuel filter, it ran fine BUT the next day it stalled again and this time it wouldnt start no matter how many times i tried. I then changed the fuel pump over, and after many many attempts to kick it over it started and ran for about a minute or two and died. Could it be my crank angle sensor? I turned the accessories on, and i do NOT hear my fuel pump turn on, or make a noise (prime) I have thumped the bottom of the tank, changed the fuses in the relay and still nothing. Does the CAS have to be fully operating in order for the fuel pump to prime (start pumping fuel) Or will i hear it prime regardless of the crank angle sensor? I havent got a conclusive answer on this - i would think if the CAS is screwed then the ECU and BCM wouldnt give the fuel pump the power (or go-ahead) to start up. So my main question is: Does the fuel pump prime regardless of the condition of the CAS? Or does the CAS have to be operational (or partly operational) in order for the pump to prime? My worry is, if the CAS has nothing to do with the fuel pump starting up then i may have an electronic gremlin, or fault to worry about as the pump is new and ive checked twice now to see if it was installed correctly. The pump just isnt starting at all.

(ive tried the cold water trick on the CAS - didnt work, but i tired this after the 6th stall and the CAS would probably be beyond resurection at this point - and screwed) so I doubt thatd help make a difference


Thanks guys, any help would be appreciated

 

[VS_Pete]

u need to have the ignition on,
lights on the dash to hear pump priming.

check for errors here is the link
https://forums.justcommodores.com.au/threads/checking-error-codes-vr-vs-revised.22307

I didn`t get any errors but after my VS cut out at 60k/hr I was lucky I got it started straight away while it was still moving I changed my cas haven`t had a problem again.
very common problem do test change cas mate.

PS welcome to JC.
This is my first computer car and I have had a lot of good help on here.
Good bunch of people and very helpful.
Cheers Pete.

 

[hako]

I'd agree with what VS_Pete_1 says above. You can change the CAS yourself if you have a puller and some sockets (not rocket science) and they are under $50 on Ebay. Could also be the DFI module (from wreckers ~$30) but first I'd try the CAS.
Good Luck and as Peter says, welcome.

 

[Brett_jjj]

No,a faulty CAS wont stop the 2 second priming of the fuel pump when the ignition switch is turned to the ON position.Ive ran into problems where I thought it was the fuel pump itself not running, but have then found a break in the fuel pump wiring under the rear of the car near the fuel tank sender etc.Its worth checking this wiring to make sure theres no small breaks in the wiring as its all exposed to the underside of the car near the fuel tank area..If the wiring is all ok,then maybe try replacing the fuel pump relay which is under the bonnet near the fuses etc.

 

[wortus]

Easiest way is to swap the fuel pump relay over with one of the other relays in the engine bay of the same type that you know works. If the pump still doesn't prime/start then remove the fuel pump relay and locate the connections in the realy socket corresponding to the normally open contacts of the relay and jumper them this should make the pump run all the time assuming there is power and the wiring is OK. If the pump does not run then it's a process of elimination working with a test light from the realy base to the connector infront of the fuel pump, when you loose power you have gone past the fault.
If all this is OK then you have to check there is a 2 second signal (+12V) coming from the ECU to the fuel pump relay coil. Power to the fuel pump is maintained via a set of contacts on the oil pressure switchwhich close with oil pressure however this plays no part in the fuel pump priming.

 

[Vee-ard]

Yeah the fuel pump isn't supposed to prime on "accessories", it primes on "on".

 

[robert422]

Hey guys thaks for the handy info! I am still having issues with the car! I have replaced the CAS (and that was a hard job with getting the harmonic balancer on and off) and the car will still not start! I tried to deactivate the imobilizer, that didnt work. I am still hearing NO priming from the fuel pump at all. The fuel level works in the car (showing how much fuel i have) if that can help diagnose the problem? Is there anything else mechanical that will stop the fuel pump from priming (starting proper operation) How can i safely test a relay to see if it is working and recieving power (charge) ? It has to be the connections or electrics to the fuel pump. How do i best test this?

What makes me wonder is the fuel pump level is sneidng a singla back to the car so the connections must be okay to the rear of the car? Which leads me to believe there is a relay problem somewhere? faulty connection or shotty fuse..

- i tried to test for error codes faults, but i had disconnected the battery for to long and the system is reading as OK as it has no codes stored in the memory.

 

[hako]

A rough and ready way to tell if the fuel pump is working is to simply loosen the fuel filter connection - fuel should leak/spray out as the fuel lines hold pressure for quite some time. If not then the pump is not working.

 

[wortus]

Hey guys thaks for the handy info! I am still having issues with the car! I have replaced the CAS (and that was a hard job with getting the harmonic balancer on and off) and the car will still not start! I tried to deactivate the imobilizer, that didnt work. I am still hearing NO priming from the fuel pump at all. The fuel level works in the car (showing how much fuel i have) if that can help diagnose the problem? Is there anything else mechanical that will stop the fuel pump from priming (starting proper operation) How can i safely test a relay to see if it is working and recieving power (charge) ? It has to be the connections or electrics to the fuel pump. How do i best test this?

What makes me wonder is the fuel pump level is sneidng a singla back to the car so the connections must be okay to the rear of the car? Which leads me to believe there is a relay problem somewhere? faulty connection or shotty fuse..

- i tried to test for error codes faults, but i had disconnected the battery for to long and the system is reading as OK as it has no codes stored in the memory.

To test a relay you can remove it from the car and apply 12 volts to the coil terminals and measure the contact resistance with a multimeter, the normally open contacts should read open circuit with the coil de energised and a short circuit with the coil energised.

Just take out the fule pump relay and bridge out the normally open contact terminals in the relay base and this will make the fuel pump run all the time even witht he ignition off. If you don't hear the pump then you have to check fro power at the tank end, this is assuming the fuse is OK and there is 12V at the relay base.
The fuel pump circuit has nothing to do witht he fuel gauge at all.

 

[Kev8]

Hi there, I am having the exact same problem. I changed the fuel pump over, the car ran for a few minutes then cut out again. I have checked fuses and relays and am getting power on the connector plug situated on the tank. There are 4 wires and I'm getting a constant on 1 of them. Still can't hear the pump switching on though which leads me to believe it must be the wires located within the tank itself on the sender unit. Is this at all possible/likely?? I know for a fact it's not the pump as I replaced it and the original wasn't even faulty. Should I have power to more wires then just the one? I have power on a second when cranking the engine. Any advice appreciated!