Depressurising system running lpg and petrol?

[FlatTyre]

So I need to replace the fuel filter on my vp commodore.

I jacked up the car, removed the fuel pump relay from the fuse box and started Up the car, expecting the engine to stall in about 10 seconds.
The car ran for over 10minutes without stalling?!
Although I have been running the car solely on petrol for a couple of days, I think it has to do with the lpg, maybe. After the engine didn't stall, I flipped it over to lpg, ran for a few minutes then switched it back to petrol again. I didn't think it would help but I did it anyway.

My main problem is, if it's not depressurised, would that pose a big problem when I take the old filter off? There is about 12l of petrol still in the tank and about 15l of lpg.
Is it possible if I clamp vice grips to the hose that runs between tank and filter to stop petrol going everywhere?
Or is there another way of depressurising the fuel system?

Thanks all.

 

[lowandslow]

Are you sure you removed the correct fuse/relay?

 

[FlatTyre]

I'm sure it was the correct one. A 30amp Bosch stating it was for the fuel pump?
That's the only one that made sense to pull out.

 

[FlatTyre]

Ok turns out I am an idiot.
I pulled the wrong one out, it should have been the fuse labeled efi.

 

[Jxfwsf]

You need to pull the fuse not the relay.
The pump is also controlled by the oil pressure switch which basically bypasses the relay when it's running.

And yes you should depressurise it otherwise it'll spray petrol everywhere when you disconnect the filter.

 

[bundybear75]

You need to pull the fuse not the relay.
The pump is also controlled by the oil pressure switch which basically bypasses the relay when it's running.

And yes you should depressurise it otherwise it'll spray petrol everywhere when you disconnect the filter.

Ah that's why mine never stalls, I have been pulling the relay and have run it for 20 minutes without stalling. I invested in some fuel line clamps and made sure to wear safety glasses and have rags ready every time I change the fuel filter. So its the fuse labelled EFI? Is this under the bonnet or under the steering wheel?

 

[defecat0r]

Under the bonnet. "15A F/Pump" is written on the fuse panel cover above the fuse on my car. It's the far left fuse when standing in front of the car. I remove the fuse, and not the relay when i'm doing this. With the car running, pulling the fuse results in the car dying in about 3 seconds, i then crank it over for another few seconds. Have fun ^_^

 

[strgas]

disconnect the fuel pump power at the tank start the engine allow it to run until it stalls .
Changed many fuel filters without depressurize the fuel lines . loosen the clamps then using a rag around the fuel hose wriggle the hose off the filter and the rag will catch any petrol spray