VK V8 elctric fuel pump / tachometric relay

[VZ1_60]

Having an intermittent ssue with the electrical connection to the fuel pump in my VK V8.

Have checked the wiring to the pump, and the pump itself, both appear to be working fine.

Power to fuel pump fuse and tachometric relay seem ok, and earth seems ok.

Car will start and run for about 15-20 minutes ( I can hear the fuel pump running), then the pump is losing power.

Sometimes it will re-start after a few minutes.

Any suggestions on fault finding?

My thoughts are:

- relay faulty (anyone know how to test)
- voltage drop somewhere
- coil fault
- wiring issue from the coil to relay
- earthing issue with the relay.

I have put an ad up for a replacement relay, Smithy has been kind enough to reply with detals of a possible replacement if that is the isse.

thanks John

 

[vc commodore]

Courtesy of a post @Fu Manchu posted up to be able to check relays

https://www.ebay.com.au/itm/266002524851

How is the fuel filter if one is fitted? Even the fuel line...Blockages?

Or do you think it is an electrical issue?

If you think an electrical issue, run a temporary seperate power and earth (minus relay), but with a fuseable link and see how that goes....Should help track down if it is actually the loom

 

[VZ1_60]

Courtesy of a post @Fu Manchu posted up to be able to check relays

https://www.ebay.com.au/itm/266002524851

How is the fuel filter if one is fitted? Even the fuel line...Blockages?

Or do you think it is an electrical issue?

If you think an electrical issue, run a temporary seperate power and earth (minus relay), but with a fuseable link and see how that goes....Should help track down if it is actually the loom

thanks.
Has new fuel filter, has plenty of fuel and runs correct fuel PSI.
Highly likely electrical as I can hear that the fuel pump has stopped.

thanks

 

[vc commodore]

thanks.
Has new fuel filter, has plenty of fuel and runs correct fuel PSI.
Highly likely electrical as I can hear that the fuel pump has stopped.

thanks

Just run that temporary power first, then the earth to determine which might be the cause....

Do they they have an internal fuel pump?

If they do, perhaps when it stops, give the tank a wack with the palm of your hand around the area the pump is and see if that jolts it into life....If it does replace the pump...Something I have done with later model cars with internal fuel pumps when they stop working or fail to start first thing on start up...

 

[VZ1_60]

Just run that temporary power first, then the earth to determine which might be the cause....

Do they they have an internal fuel pump?

If they do, perhaps when it stops, give the tank a wack with the palm of your hand around the area the pump is and see if that jolts it into life....If it does replace the pump...Something I have done with later model cars with internal fuel pumps when they stop working or fail to start first thing on start up...

thanks
I have both an internal and external pump wired through separate relays, however relays are triggered by the original wiring from the tachometric relay. Both pumps stop when it loses power which is why I am confident it is an electrical issue.
Will try the wiring bypass to try to chase down the issue.
thanks everyone for their help.
cheers, John