broke the ignition terminal?
well that would explain the hissing sound, burning while it was turned on i suppose.

good job finding that :o)

Found the problem. The guy installed the ignition just happened to broke the ignition terminal. The battery ran down because the light switch was on all night and nobody around after dark to notice it. Well, greatly appreciated for your help. Surprisingly after sat more than a year outside and this old forklift started and run smoothly beside the hydraulic is slow.

Btw, last night as the battery is hook up to the forklift, it run down. Do you happen to have diagram for connecting that ignition switch?

No sir, the propane was off. Just trying to crank the engine and there is hissing electronic noise when ignition is put to start. lights for the oil and ignition are lit

Hissing sound ?
Is tbere any noticeable odor of propane when you hear tbis?

Thank you for your reply. The engine starter was not engared. Only the hissing sound when turn the key. Battery is good. The forklift is using propane. We suspect it is the wrong installation part or might be loose connection from corrosion due to the forklift sat outside the whole time and rats might get to the wiring.

it is possible he may have hooked it up wrong
but if the engine turns over and the dash lights light up when turned on then most likely it is hooked up correctly.
there may be another problem since it has been sitting for a year.
the rules we all follow and are taught in troubleshooting a lift are these things.
you have to have:
1- Air
2- Fuel
3- spark

As long as there is nothing mechanically wrong with the engine then it should run based on those 3 basic principles.
If any of those 3 things are not happening then you have to troubleshoot the system relating to the problem.

- pull a spark plug wire at the spark plug and see if it fires when you spin the engine over, if you have spark then go to the fuel system.
- depending on what type of fuel you use make sure you are getting it to the carb for gasoline or mixer if it is lpg.

Note: if lpg there is an electronic fuel lockoff valve that has to open before it gets fuel, if it sticks closed (even if you hear it click when the ignition is turned on), being stuck it will not let the fuel go into the filter lockoff or vaporizer.
If it does work then check the fuel input to the mixer, pull the supply hose at the mixer and spin the engine over, there should be a small amount of lpg fuel that comes out of that, its not very strong but you should be able to hear it and actually smell it coming out of the hose when trying to start the engine.

if you are dealing with a gasoline engine then of course you should make sure it is getting fuel to the carburetor and is squirting fuel into the intake when the accelerator is pressed.

- check the air filter, remove it if necessary to make sure it is getting enough air.

These are just some basic things to do when troubleshooting a no start situation