LPG and cold starts

[hendrixhc 10,918]

Just thought id ask the question.

 

The XC is a biatch to start when it is cold and being that i know fark all about lpg i have done a bit of research.  It would appear that  a priming circuit maybe be the answer.

 

From what i can understand you hook a a gas solenoid to a press button which you hold down for a few seconds to fill the inlet manifold with gas.

 

Is this correct and if so any tips on where to connect and how to connect? 

 

[adrianphu123 73]

make sure your mixtures are good i.e. get it tuned and try holding the throttle open a little bit. Not a lot, just experiment with it until you get it right

[Lord_fahrquhar 2,580]

Lp can be a bit of a cunt if it's a simple mixer ie Amos ring. a good way to check is to get it started and on the converter fiddle with the idle mixture screw. This is only a small screw nit the big brass one. Usually sits next to the outlet.

 

The big brass one is sensitivity so crew it in to reduce it screw it out to increase. It's like accelerator pump in a carby.

 

The in line screw is fast speed this is the last to tune only if it stumbles up high.

 

Balancing these is a cunt.

 

If its a lovato or impgas system much easier as these adjustments are done on the mixer not the converter.

[dizzy616 183]

i seem to have this weird ass problem with my ute. i tried having the pulse wire connected to the neg of the coil. like you should see on most. but when it was cold. it was a real uber c**t to start. i tried wrapping it back around  the spark leads. i wrapped it around a couple to make sure 1-5 like it originally had. hardly have a drama starting it up. real weird issue but you can maybe try that

[gerg 10,871]

Your gas relay should have a priming function that turns the solenoids on for a second or two when you turn ignition on. Having a separate switch to turn on the solenoids would be illegal as you are bypassing a safety interlock designed to switch off when the engine cuts out. There's either something wrong with the gas relay that's stopping it from giving it a prime or your tuning is a bit out.

 

My LPG Corty would start first kick, winter, summer, stinking hot or icy cold with barely a revolution of the crank. You can get them pretty good if you play with them and all the gear is up to scratch.

 

I didn't get what mixer you have.

[nickd 111]

Are your cars running duel fuel?

 

My neighbour today had trouble starting there falcon (I'm the mechanic for the street), told them to start the car on petrol as LPG will freeze up with cold weather.

Started straight away on petrol as it was -1 where I am this morning.

 

Gas isn't good when its cold but I'm all ears for info.

[dizzy616 183]

lpg shouldn't freeze up if its pure. but with all the impurities in the gas from usual servos. the impurities will freeze up. at least thats my understanding of it anyway. if you fill up at say supergas or something then you shouldn't get all the impurities.

and yes mine is duel fuel but petrol doesn't seem to work so i tuned it for gas. i dont use petrol in it anyway.
problem with my system i tend to think that the negative on the coil isn't all that good. or the negative wire.

i found the wire there where they actually cut the wire. tried re-attaching it and i had problems with starting in the cold. i had problems when i got to 120 'i done it in a quiet spot' then the it start surging a bit.

though getting the pulse feed from the spark plug leads. it starts up with hardly any problems. freezing, cold and warm with only a couple turns. and no surging problems at 120. i figure im not going to bother about it until i need a new coil.

it still gets good spark

[deankxf 20,266]

gas wont freeze up when its cold,

cold does cause issues sometimes, usually with the crap thats in the converter(waxy by product in the gas builds up over time) when its cold, the wax stiffens and valves cant open.

can pour warm water over the converter first up to test if its this.. if its fine, likely needs cleaning.

 

also old diaphrams inside the converter stiffen over time which are worse when cold.

 

Landi converter like my car has is most common for cold start issues(have only had 3 issues in 5 years though) when the wax is an issue, manifold vacuum pulls the valve open as it should and the wax build up prevents it from closing, so it floods with gas and can freeze the converter.. (trick to get going after this is to turn the switch to no fuel.. crank it till it fires meaning all the gas is gone then go get some water and tip it over the converter.. or flick it to petrol instead.. sometimes this is one off, sometimes it must be cleaned.

[hendrixhc 10,918]

Sorry should point out this is an impco system with dedicated gas.

 

I think the engine could do with a good service and tune, which will be first port of call very soon.

 

I recon the next thing will be to piss the gas off and go back to fuel.

 

Thanks for all the suggestions by the way.

 

I was trying to start it when it was about 1 degree outside.

[deankxf 20,266]

Sorry should point out this is an impco system with dedicated gas.

 

I think the engine could do with a good service and tune, which will be first port of call very soon.

 

I recon the next thing will be to piss the gas off and go back to fuel.

 

Thanks for all the suggestions by the way.

 

I was trying to start it when it was about 1 degree outside.

 

could pour warm water over the converter and if it starts fine, you know its the converter.

when in good condition gas shouldnt be an issue in the cold.. mine was cross firing the other morning from moisture on the cap and leads etc.. thats tune related, of which they are way overdue(been on the car 18 months, but came with the motor that sat under a tree for 3 years prior)

[bear351c 10,270]

Agree with deankdx, flick gas/petrol to "neutral" and try cranking the engine til it 'kicks'. Then flick back to Gas. Had this help me in the past.

Also, a GOOD ignition system is imperative for LPG. 9 mm spiral bound leads, good cap/rotor and coil. Plugs generally one range hotter and gap closed down 0.1 may help.

[hendrixhc 10,918]

Ok  so i did a bit of horsing around with this stupid gas system tonight and came up with a result. Directly below the convertor is a solenoid with a thin hose that runs to the bas of the carby.

 

 

 

I pulled this hose off the carby end and plugged it with a bolt. Tried cranking it and it fired up straight away.

 

This is where it goes into the carby. 

 

 

Once it was running i let it warm up for a bit and then shut her off and reconnected the hose, tried cranking it again and it fired every time.

 

Any thoughts on what this hose is?

[deankxf 20,266]

they've set that up as a primer

i would assume it only kicks in when its powered up(some have set these to supply extra gas on start up so check where the wires go on that solenoid you have circled

[adrianphu123 73]

that looks to be a primer. What are the wires from the solenoid connected to? there might only be one, the other is a ground which grounds on the bracket.

[hendrixhc 10,918]

that looks to be a primer. What are the wires from the solenoid connected to? there might only be one, the other is a ground which grounds on the bracket.

 

Ones definately grounded with a green curly wire! They other shoots off into the black mess that is the engine. Where should it go? any ideas? I am going to degrease the motor this weekend and can trace its origin then.

[adrianphu123 73]

i would not recommend wiring it to the starter, which seems to be a real smart idea, but could result in flooding if the motor doesnt need a prime ie. when hot. Try connecting it up to a "momentary on" type push button switch and only giving it a quick prime when needed.

[deankxf 20,266]

Ones definately grounded with a green curly wire! They other shoots off into the black mess that is the engine. Where should it go? any ideas? I am going to degrease the motor this weekend and can trace its origin then.

some people have hooked them to the starter motor trigger(i dont like this because if it doesnt start it can flood with gas... you can check if its flooded by turning the gas off if it has a switch?)

it may have a separate primer button in the car, turn ign on, pressing the button releases some extra gas, and then fire it up.

[hendrixhc 10,918]

will do guys. will have more of a play tomorrow. Thanks for your help!

[deankxf 20,266]

 

adrianphu123  is either a mind reader or a copy cat from the future lol

[hendrixhc 10,918]

I thought you guys were sitting next to each in the same room!