Yellowshark
Well-known user
During diagnostics of my recent backfire problem I noticed that my fuel pressure was not quite right. The FSM spec is low 50s to 62 psi with a drop in the first minute of the pressure test of no more than 5psi. Whilst I was registering a healthy 58psi I was dropping 6psi. I am finding it difficult to get excited about that, but maybe it is could get worse and go phut when I am 400 miles from home an so I probably out to look further.
So it seems to that an early test is to test the pressure at the inlet manifold which will either place the problem at the rear of the car or at the front with the fuel rail and injectors.
The FSM solution is to fit a GM tool which connects in between the fuel line and the inlet manifold and lets you turn off or on the fuel supply. BUT whilst I have found this tool on ebay it is 150-200 USD (plus freight/customs) which is just too expensive for what would probably be a one of use.
An alternative is Amazon which has plenty of plastic on/off valves for £20 but all seem to be used with lawnmowers etc. and my brain is telling me they will not work with the C5 fuel pressure.
One solution that occurs to me is to unhitch the fuel line from the inlet manifold and fit my pressure gauge into the fuel line but I have never worked on a fuel system before (apart from carburettors on the old cars) , know nothing about these quick connectors that are used on the C5 and no idea at the moment if I have a suitable connector in my pressure gauge box that would allow to do that.
So has anyone had to confront this on their C5/C6 and what did you do?
So it seems to that an early test is to test the pressure at the inlet manifold which will either place the problem at the rear of the car or at the front with the fuel rail and injectors.
The FSM solution is to fit a GM tool which connects in between the fuel line and the inlet manifold and lets you turn off or on the fuel supply. BUT whilst I have found this tool on ebay it is 150-200 USD (plus freight/customs) which is just too expensive for what would probably be a one of use.
An alternative is Amazon which has plenty of plastic on/off valves for £20 but all seem to be used with lawnmowers etc. and my brain is telling me they will not work with the C5 fuel pressure.
One solution that occurs to me is to unhitch the fuel line from the inlet manifold and fit my pressure gauge into the fuel line but I have never worked on a fuel system before (apart from carburettors on the old cars) , know nothing about these quick connectors that are used on the C5 and no idea at the moment if I have a suitable connector in my pressure gauge box that would allow to do that.
So has anyone had to confront this on their C5/C6 and what did you do?