VS commodore poor fuel economy

[HonoraryPants20]

Completely forgot to add but when I did my fuel filter a little over a year ago the fuel tank breather line literally cracked off. It also wasn’t connected at all I literally pulled it out with no effort so that may be the fuel smell but I’m unsure if that would cause the bad fuel economy but I will be replacing that hopefully soon.

 

[grey_hawk]

That would be your fuel smell and you could lose fuel from the breathers.

 

[HonoraryPants20]

Just an update I’ve fitted the aftermarket fuel regulator but I’m not sure if it works yet due to one of the fitting leaking which I’m fixing tomorrow. If it all works fine I will update if this has solved my issue if not I’ll be dropping the tank and replacing all the lines and gaskets.

 

[gtrboyy]

What pressure is regulator set at & do you know what factory setting is?

Check it with a guage to be sure.

 

[HonoraryPants20]

What pressure is regulator set at & do you know what factory setting is?

Check it with a guage to be sure.

The regulator does have a gauge I think VS’s are suppose to be around 43 psi at least that’s what I’ve heard. Also I haven’t set the pressure yet as I can’t turn the car on due to the leak.

 

[stick3]

i fitted a adjustable fpr back in sept and got a mechanic to check the pressure, he found it was a little high from what i had it set at and you dont know how accurate the gauge is
this is pic is after he adjusted it
<a href="https://imgur.com/oj7PwJ5">

 

[VSLesFez]

I made my own gauge.Pressure runs about 44 psi, and up and down a bit...My VS V6 has given me endless headaches since l got it.
One important thing I learnt that causes very bad ecconomy is very low VACCUUM in the inlet plenum.Most v6s Ive worked on run at minus 5 vaccum pressure.Many inlet plenums leak air coming into the plenum between the inlet manifold and the plenum.The best way I got around this was make my own gasket from THICK gasket paper..I bought it from repco or bursons.1 milimeter thich is very good.or make 2 gaskets from half a milimeter gasket paper. Use good heat resistant silastic to seal it .After I did mine, vaccuum went up to between 7 and 8 .The VT /VY gaskets are metal ,and ONE use only.I dont like them ,They leak bad too.I go paper gasket.

 

[greenacc]

Where did you get your parts from? There are lots of fake parts around like spark plugs. If you have ended up with a few such parts they might give you issues with economy.
I used to strip down a lot of old engines and ecotec is getting on in years now. I wonder if you have a huge amount of carbon on the valves or low compression that's sapping power causing you to give it more gas. Does it burn much oil?

 

[VSLesFez]

Low kms engine,fully overhauled about 30,000 kms ago.LPGas heads.and much much more done.Most of the car is new or recod,,Doesnt burn oil.The ecu is the issue with me.VS ecus loose memory..I have to find someone that can reprogram the ecus,,not performance program,just factory settings.Or do a economy program.I lve in brisbane..One commodore wrecker in melbourne did a economy tune on the ecu when it was on duel fuel,The ecu came alive and performed so good.His alteration to the settings rebooted the ecu from sleep mode or forget mode to get up and go better mode.The car ran slower on overtaking on the highway,but better everywhere else.Its too far at the present time for me to drive to melbourne to get it done again there.Im thinking of LPG installers, they might do a resey or lpg program on the ecu and hopefully reboot the bad ecu as it is.

 

[HonoraryPants20]

Just an update I fixed all the fuel leaks and tried turning it on but it refused to. I played around with the aftermarket fuel regulator for quite a while and never got it to work so I ended up putting the factory regulator back in but I put my spare regulator from a 95 VS I got a couple months ago at the wreckers. It now turns on just fine how it use to but will update if this regulator fixes my issues. Also I try to get all my parts from repco but some parts I get from eBay when repco does not have them or doesn’t have them in stock. I did get my o2 sensors from eBay but they were from a seller with thousands of reviews so I trusted them. Also I don’t think it burns much oil as it doesn’t blow any smoke unless it’s really cold outside and the car hasn’t been turned on that day. I was possibly planning on buying the MACE memcal as I’ve heard very good things and it also improving fuel economy. Also I drive it very nicely it rarely does above 2.5k rpm’s unless I need to get up to around 100 which doesn’t happen much.