lpg/petrol switch over not working??

[two1/4jim]

Hi. Went to start the 110 pickup a couple of days ago and it wouldn't start. Had a good spark, so checked fuel flow and non coming though... checked fuel pump using a spare battery and it was fine so clipped a bulb to the electric supply to the pump and there was nothing. ? so I'm guessing that theres a gas to petrol switch/ solonoid which has gone kaput when I switched to petrol when I turned the landy off last. or is there another possiable explanation... poor dogs sick too but I don't expect anyone can help with that, he's probabally just eaten too much rubbish...

 

[two1/4jim]

forgot to say that I have no previous experience with lpg so any advice greatfully received

 

[psychoideas]

I don't know what system you blokes use over there.....but....If you have an electric fuel pump, the LPG safety switch may be connected to it. This will stop your fuel pump from operating in the event that you crash, the engine stops, a fuel line is ruptured but the ignition is still on. It's hooked to the coil wire and can tell if the engine is running or not.

This safety switch is mandatory down here for the LPG side of the system.



So.......you need to have someone crank the engine with the key while you put a test light on the fuel pump supply.

Also just check that all the spade connectors are tight on the fuel and gas lockoffs. My mates car wouldn't start one day and it turned out to be a loose connector.
Good luck

 

[two1/4jim]

Well it makes sense to have a fuel pump cut off like you say psychoideas so I would expect that theres one fitted. I'll have a closer look at the coil tomorrow. I did check the fuel pump supply whilst cranking with the key and had the lamp where I could see it and there was nothing. Loose connectors!!! I shall go though them all in the morning... cheer for the ideas mate.

 

[jasper110]

on my lpg set up, you can hear the petrol pump running even when on lpg with just the ignition on. i'm off outside to investigate.

 

[jasper110]

on my lpg set up, you can hear the petrol pump running even when on lpg with just the ignition on. i'm off outside to investigate.

yep. on either lpg,petrol or the middle (both off) the petrol pump still runs. the wire from the coil tells the cut off solenoids if there is power to the coil and the engine is running, in order for them to open (or close). can you still run on lpg? can you hear the solenoids clicking if you toggle the fuel switch from one to the other? if not this may suggest a faulty cross over switch, though this shouldn't affect the fuel pump.

still thinking, when checking the fuel pump with the spare battery, did you check for flow (petrol)at the carbs? if not, do you have a flow of petrol on the tank side of the cut-off solenoid thats most likely under your bonnet.this will tell you if the solenoid is at fault. if the solenoid is at fault, it has a knurled knob (small) underneath it which is a by-pass,screw it all the way in (or out) and check again.

if it's none of the above it's perhaps down to the wiring to the pump from the ignition.

in summary, my lpg system has no effect on the fuel pump, its switched from the ignition via the key. the lpg does controll a fuel shut off solenoid and if the lpg system has no power (it comes from the coil, or a switched ignition) the solenoid will be shut and no fuel will come through.

hope this is of some help.

 

[two1/4jim]

Thanks for taking time to have a look for me there jasper110. I did check the flow into the carb' when I tested the pump and it was fine. Thinking about it now though I did have to turn a flow tap under what I presume to be the solenoid to the postion "open". It had prevoiusly been in the fully closed postion. So that will be the bypass then next to the vapourizer? See pics. There's electric via the yellow cable so I guess it must be this thing however when flicking the dash switch from Gas to middle to Petrol you can hear the thing clicking on the bulkhead. Would it make that sound if it wasn't working? Maybe its sticking... Guess the only way to see is to swap it and see...?

 

[Tommo32]

shouldnd the lpg system cut the fuel pump off as well as the solonoid valve? otherwise wouldnt the pump burn out or something?

 

[LandyV8]

Mine had a similar problem. I couldn't get gas or petrol. There is an inline fuse in my system that had blown and it wouldn't power the pump for petrol or gas. Replaced and working fine again.

 

[two1/4jim]

Mine had a similar problem. I couldn't get gas or petrol. There is an inline fuse in my system that had blown and it wouldn't power the pump for petrol or gas. Replaced and working fine again.

Well that sounds more like it! I've just been out and had it running off petrol by using a spare battery to power the fuel pump with the hope that I could switch it over to gas once she was warmed up. however there doesn't seem to be any gas coming though either. I originally thought that something must have fused but I couldnt find one. Wish I was a bit more mechanically minded. I'm off to have another look now. fingers cross that I find something... supposed to be using the pickup this weekend to collect a load of building materials.

 

[LandyV8]

Well that sounds more like it! I've just been out and had it running off petrol by using a spare battery to power the fuel pump with the hope that I could switch it over to gas once she was warmed up. however there doesn't seem to be any gas coming though either. I originally thought that something must have fused but I couldnt find one. Wish I was a bit more mechanically minded. I'm off to have another look now. fingers cross that I find something... supposed to be using the pickup this weekend to collect a load of building materials.

the way my switch system works is it shares a live between the petrol pump and the LPG pump. The live goes to the switch and if the switch is in the petrol position it sends the live to the petrol pump. If it is in the LPG position it turns the Gas system on. Also if it is in the middle it cuts power from both. I hope this helps

 

[two1/4jim]

Traced wires and can't find a fuse. however it now seems to start on gas (something which it doesn't normally do when cold!!) but stops as soon as you turn it onto petrol. You then have to flick the switch a couple of times with the ignition key in the right place to get it the gas back on and start it up again. Gonna have to book it in for an lpg checkover. Hopefully I can drive it to the garage now. wierd...

 

[jasper110]

when you flick the switch from gas to petrol, the engine will stop instantly as the gas supply has be shut in an instant. it takes a while for the float chambers in the carbs to fill which is why you need to wait a few seconds before it will start on petrol. if you are running on petrol and suddenly switch all rthe way to gas, you will flood the engine as it now has to run the carbs dry of petrol as well as having gas going into it. this is why the switch is 3 way, middle position being all off to use up residual petrol in the carbs.
others are right i also have a 10amp fuse from the coil feed to LPG system (its about 2 inches from the coil) as you have no doubt gathered, all systems are slightly different. my constantly running petrol pump is still going strong after 3 years.

 

[two1/4jim]

when you flick the switch from gas to petrol, the engine will stop instantly as the gas supply has be shut in an instant. it takes a while for the float chambers in the carbs to fill which is why you need to wait a few seconds before it will start on petrol. if you are running on petrol and suddenly switch all rthe way to gas, you will flood the engine as it now has to run the carbs dry of petrol as well as having gas going into it. this is why the switch is 3 way, middle position being all off to use up residual petrol in the carbs.
others are right i also have a 10amp fuse from the coil feed to LPG system (its about 2 inches from the coil) as you have no doubt gathered, all systems are slightly different. my constantly running petrol pump is still going strong after 3 years.

Yes I know about the three-way switch and give the switch over between fuels the time they need but it still stalls and then won't restart on petrol. I still can't find a fuse. given up on that one. 'reckon you're right about them all been different too... makes it hard to pin down whats up when you haven't come across lpg before.

 

[Rust_Spot]

If the lpg switch fuse was blown it wouldn't run on gas either so it can't be that. But if you really can't find one I'd add one for safety - 7.5 amps is the correct rating.

If it's wired correctedly when you switch to petrol this should energise a relay. The lpg switch shouldn't directly power your fuel pump. When I was fitting mine the LPGA man said it can cause the switch to burn out.

So perhaps you could check if there is a relay in the wiring going to the fuel pump? That could be faulty.

 

[lozzd]

Only slightly related, but I once solved a problem on an LPG system because the tank had bounced on the earth wire for the solenoid, slicing it in half. So if you have any wires running anywhere where they could get damaged, or somewhere where the earth could be dodgy, that might be it. Unfortuntaely your system will probably have rather a lot of wires.. Good luck anyway!

 

[ANTOFEM]

All my switch indicator is off. Not showing petrol or LPG, and vehicle will not start.

 

[mikeau]

16 1/2 years...

 

[woodnet]

Well I'm still running my 1986 LR90 on dual fuel, or did until I had the same changeover switch issue! It runs OK on petrol, but when switching over to gas no green light and no solenoid click from the tank behind me either. It is a primitive BRC Bristol 42 system, and I can't find a matching 6-pin 3-way switch to replace with. Very difficult to find any LPG technical support these days, so may be time to remove it? - if I can find anyone in SE England prepared to extract it!