Duel fuel issues

[helpmefixmybommodore]

Hello everyone, a while ago I posted a thread talking about issues with my 94 vr with a LG2 Duel fuel buick, Turned out to be a weak ignition system. I am currently having a issue with the car now, and am seeking some advice/knowledge from the community, thank you in advance.

So I drive car to work in the morning, knock off and go to start and it rolls over and fire's but no ignition. The car was running fine in the morning (on gas). I believe it is fuel related, have spark n air. But the thing that boggles me is that it doesn't start on LPG or ULP? Are their systems that tie the two together? At this stage am leaning towards taking to mechanic, but would rather have a better idea on what the issues is rather than paying $$$ in order for someone to tell me its a simple fix

 

[Trevor loves holden.]

Duel starts on fuel then switchers over that's why they recommend to keep them above a quarter of a tank of petrol so you don't damage fuel pump, you can try swapping fuel pump relay, can you here the pump working? Is there fuel in the rail? If your getting spark while cranking you will have to figure out if its the key head and contact point around ignition stopping the fuel pump as it tells the pcm to activate earth to the relay or the pump is either stuffed or a crack in the wire somewhere, or does it start after 30 seconds of cranking on lpg? Also test the injectors to see if they are all getting power you can use a test light or a multimeter.
Only other things are the CAS or your cut off solenoids that open and close your lpg and fuel. A bad duel switch also can cause a issue, good luck with the hunt, just start with the basics then work your way through each to cross them off the list.

 

[woteva]

Wow !!??!! Dueling fuels.... Which one will be the victor ?

 

[Trevor loves holden.]

Is the control module lights on to confirm power to module.

 

[helpmefixmybommodore]

Yeah **** after reading about duel fuel set ups I never read that they started on ULP then switched! My fuel pump dying would make sense as their was no fuel in rails while cranking, nor was my fuel pump priming. I didn’t consider this as much due to me not knowing prior to this that the duel fuel systems switch from ULP to LPG when staring. Thank you for this information, very helpful. I’ll get on to it. Cheers!

 

[apollo13]

If you have a changeover button or switch, typically you can hold it for 5 seconds, and the ECU will change over to start on LPG alone. I dunno what system you have. Should fire up in summer easily. Otherwise get an assistant to spray some aerostart into the air filter.

 

[Trevor loves holden.]

30sec of cranking usually gets them going, don't know about holding the switch in never herd that one before cant see that doing any think as their only 2 options lpg and fuel, holding it in is just stopping the momentum between the 2 its not a glow plug lol, change out your fuel filter while your at it.

 

[woteva]

Many many moons ago I used to install VIALLE LPG systems when VN/VP and EB Falcons were new. The systems we fitted had a dual colour led switch where it was red for petrol and green for gas. I am sure it was the VIALLE systems fitted to these new vehicles at the time as we did install many other brands including Impco, Landi Harthog, Lovato.

To reduce the risk of backfire when on LPG, they would start on petrol first and then switch to LPG after a few seconds. There was a "secret" mode where it would start on LPG but were told to only use it in emergency by holding the switch on for 5? seconds just before cranking with increased risk of backfire if the throttle pedal was pressed.

Backfire once or twice with no problems you should buy a lottery ticket, but I did see plenty of split air boxes and vacuum balls blown apart to know it was a big risk.

 

[apollo13]

To reduce the risk of backfire when on LPG, they would start on petrol first and then switch to LPG after a few seconds. There was a "secret" mode where it would start on LPG but were told to only use it in emergency by holding the switch on for 5? seconds just before cranking with increased risk of backfire if the throttle pedal was pressed.
Backfire once or twice with no problems you should buy a lottery ticket, but I did see plenty of split air boxes and vacuum balls blown apart to know it was a big risk.

One of my cousins inherited a small fleet of Falcon taxis. He told me that the shattered air filters was a problem for the GM3800 engine with simple
mixer LPG system, which was why the Falcon became the dominant taxi (until hybrid Jap cars came along).

 

[Trevor loves holden.]

One of my cousins inherited a small fleet of Falcon taxis. He told me that the shattered air filters was a problem for the GM3800 engine with simple
mixer LPG system, which was why the Falcon became the dominant taxi (until hybrid Jap cars came along).

I only blown 3 on mine so far in the 14 years I've owned it, lol, even tried the backfire flap which meant to stop the box from blowing apart, well that never worked.