I have a 2010 Manitou CG-18 S1 forklift fitted with a Nissan Engine. The forklift was running fine and then started to cut out and idle/run erratically.
The forklift runs on LPG Bottles via the following:

Tecalemit 3 way Electrovalve
Impco Cobra Vaporiser/Regulator, Impco VFF30 Vacuum and Fuel Lock Off/Filter
Impco External Cartridge Filter (F-830).

The Carburettor is a Impco CA55 173-3.

The Carburettor, Vaporiser/Regulator and the Vacuum and Fuel and Lock Off/Filter Assembly
and External Cartridge Filter (F-830) have all been stripped down, cleaned and rebuilt.

The External Cartridge Filter (F-830) housing was stripped and found to be empty.
There was no fuel filter present ?
Is this fuel filter required on a forklift running LPG ?

All rubber hoses were clear of foreign matter as was the Tecalemit 3 way Electrovalve that connects to the Vaporiser/Regulator.
What is this for ?
Recirculating unused LPG into the inlet manifold ?

No damage was found on any parts, although their was some dark grey dust and metallic/metal particles over all the internals and choking up the Vacuum and Fuel and Lock Off/Filter assemblies.

What could these be ?

Dirty LPG ?

This has all been refitted to the forklift.

Since refitting these parts the forklift will not run properly when you put load on on engine with the accelarator pedal whilst stationary.
The engine backfires and then cuts out.

The engine will idle, albeit sounding like it is misfiring which seems to clear when accelarator pedal is pushed whilst the forklift is stationary and when the pedal is released the engine backfires and cuts out.

Could this be due to a lean LPG fuel mixture ?
Weak spark, distributor timing ?

The rotor arm, spark plugs, HT leads, throttle cable, and all vacuum hoses have been checked found to be in a servicable order.

Ideas welcome as I am at my wit's end with the **** machine.

Please see attached pics.

Regards

Richard