Lpg Cutting Back To Petrol 3,000 + Revs

[crispinchurch]

2003 lpg 3.3 

runs fine on petrol a bit low on power 

switches over to lpg ok  

at 3,000 rev+ will cut back to petrol beeping switch back to lpg will run fin untill pushed to between 3,000 + and will cut back again

filter on evaporator changed every 6000 

 

any ideas please 

[Semmysonic]

I have had a similar problem but it happens quite rarely and only under hard acceleration at motorway speeds. I would guess it's a problem with the pump not supplying enough fuel so it switches back as a safety.

Probably best to take it to an lpg specialist to have the system tested thoroughly

[bignev]

Hi guys,

i've not had this problem as yet, anything I can think of is only a guess,

 

Is it when you are a little low on gas so not as much pressure, but they should work down to nearly empty because the stored pressure is way higher than the working delivery pressure, so if it was related it would be the pressure regulator from the tank to the front end, not allowing enough flow. (as there isn't a pump - it works on the pressure of the gas pushing it through, same as a house gas system principle)

 

or the vacuum hose to the evaporator from the inlet manifold, leading it to mis read the suction pressure,

 

but as semmysonic says, lpg tech guys should be able to read why it does it if they take it out rigged up to their kit.

Edited December 27, 2017 by bignev

[crispinchurch]

hi

it happens anytime full or empty but more times when less than half tank

the pressure which over was set at .75 to change back to petrol 

i changed this as i saw on instruction .5

this has improved it a lot 

i have tested the diafram 

 

many thanks for your help

[bignev]

Ah good stuff mate.

 

If the system is a few years old that diaphragm could be getting a little "stretched", it happens frequently on central heating boilers, a regular source of repair work for me on some models! Some have a hot water one, pump flow one, and the fan "air pressure switch" also has one.

 

But good yours is improved!!