I own a vt 1999 3.8 ltr on the dual fuel which seems to run fine on petrol, then whilst on the free way i can flick it over onto the gas and it will run fine until i have to slow back down and it stalls out. can anyone explain what the problem is to me and maybe even let me know how to fix it?

I assume this is dual fuel.... LPG and gasoline??????? Is cooling system full? If so, probably plugged filter on LPG convertor. If you are not knowledgeable with LPG, get someone who is. LPG is highly explosive.

when it is running on gas , the petrol components dry out and rubber bits crack and jam
it is also possible that the change over solenoid is not stopping the gas and opening for petrol either starving for petrol or running both fuels and flooding out
Take it to an accredited service center that works on both gas and petrol and have the problem properly diagnosed and a quote

obviously gas.

My best guess is yes. The computer is probably registered a malfunction in that line. The best way to find out is have vehicle scanned at autozone or similar.

I think you were on the right track with the fuel filter change. I would purge the system. My guess is that you still have some debris in the tank which is causing a FLOW problem. You can have a restricted flow and still have sufficient pressure to start the motor and run for a brief period, but at highway speeds where the amount of fuel is as important as the pressure it seems to be falling off. Reinspect the fuel system for debris and/or restrictions. Good luck.

The fuel system is switched from L.P. to petrol by use of a solenoid.
The soleniod is operated by a relay.
The relay is electrically protected by a fuse.
Check all 3 starting with the fuse and checking back.
Please let me know what you find.

Hi pal, I have been having similar problems with my gas conversion. I have a petrol mercedes sprinter that when it decides to run it runs fantastic, no complaints. However after spending the best part of £800 to solve the problem in several different garages things just seem to be getting worse. Every mechanic that I have spoken to has given me a different cause to the problem and 'fixed it' only for me to find that as soon as I get it home the problem reappears.If I keep it on petrol it runs fine, but if I change over to gas after a warm up period it makes a noise like it is trying to '**** ' the gas through but then the engine starts to sound like (you may remember this sound from childhood!) a lollypop stick clicking against your bike spokes. After a very short period the engine goes in to idle and finally cuts out. I am unable to turn the gas back onto petrol while this is happening.Occasionally if I stop the Sprinter and switch off the engine while on gas when I turn the ignition on again it can , when it feels like it, run absolutely fine again. The lollypop stick noise goes away and its great. Mechanics specialising in Sprinters have so called run diagnostics and have found no problem but they felt the need to change the wiring loom to solve the problem, that didnt work. Auto electricans have looked at it and have said it's possible there could be a dodgy wire somewhere! It has been back to the conversion garage and they say everything is working as it should, it must be a petrol problem. I am tearing my hair out over it. If you have since solved the problem I would be ever so grateful if you could let me know how it was solved. Thanks Helen from St Helens England.

You didn't say if there was an engine light on. I'd check the t.p.s. throttle position sensor. It could be a jumped timing belt,based on the year , it's got milelage.

Whats the difference between petrol and gas? Dual fuel ? lpg