lpg truck wont rev

[new2zukes]

hi all my winch challenge truck has been sitting outside for 3 weeks without starting and went to start it today and It wouldn't start, then when I finally managed to get it to start it wouldn't rev past 2k. it runs an impco lpg mixer and vacuum shutoff valve and carb. ive pulled all the bits apart and checked for smooth operation and all seems well. nothing has been done since I parked it up so it makes no sense that it wont work now. does anyone know what could be causing this? oh and its a Toyota 4y motor. thanks.

[tweake]

can sometimes be the weights in the distributer being stuck in old grease.
can you squirt a bit of petrol down the spout and see if it revs ?

does it still have factory carb?

[new2zukes]

the dizzy is an electronic dizzy don't know if that matters as for the carb it is the impco carb so no not factory. will try the petrol thing threw one of the vacuum ports to see if it revs

[Campbell.s]

Hi, is it an impco vff30 by chance? Also how old is the lpg your running it on? It can go stale and even be a bad batch of fuel, I've got 3 lpg GM V6s that won't start or run shit all from a crap batch of lpg

[mudlva]

how much fuel do you have?
fire some engine start into the air intake, if it revs good then its not the timing etc
start checking the over condition of the lpg lines pipe work etc, make sure you havent crushed a hose or bent a pipe
lpg can wax up in the heat converter and mixer generally through lack of use and being used for only short runs etc
imho bollix to the fuel going off, i know of an old fj that was stored for over ten years in a barn, we dragged it out and the oil was that solid we used a heat gun to get it to flow out of the sump plug.

new oil and a bit of engine start and it started and ran for over half an hour all on the original lpg fuel.
dont quite know how you get bad lpg as its not like you can pop the top off the gas cylinder and introduce a contaminant, and it doesnt evaporate like petrol???

[Campbell.s]

I'm a forklift mechanic, and Iv dealt with countless bad bottles of lpg, change the bottle for another and they run fine, hence why 3 brand new machines all go down at once, not all gas suppliers are equal.

[mudlva]

I'm a forklift mechanic, and Iv dealt with countless bad bottles of lpg, change the bottle for another and they run fine, hence why 3 brand new machines all go down at once, not all gas suppliers are equal.

humm it has to be how its stored then or willful contamination as its not like somebody could easily introduce a contaminant,
how do you get old fuel out and replace it with new fuel, without have the fire brigade turn up looking for a gas leak?

[new2zukes]

thanks all for the replies, ran out of time today to get anything done so will see how I get on this week.

[3VILC]

You can empty them in a controlled area. Like a customer when I was working at BP in Dunedin (in winter) wanted their modified gas bottle topped up. I said I'd give it a go but if it leaks I'm emptying it.. sure enough had to take it out the back and empty what gas they had got in it. How we will keep warm its freezing? Should've thought about that before you mucked around with your bottle!
The old clip-on coupling, known to leak at the best of times, obviously they'd pinched it off an expired cylinder or something and fitted it to a newer quick-screw bottle, which is ok but they obviously took a while to work out it was a leftie thread and had completely munted the clip on barb haha.
Anyways..sorry for the thread jack