LPG forklift fuel consumption problem

[Cmark]

Hey guys. We've just bought a secondhand Crown forklift on LPG. It runs great but it's got bad fuel consumption. We just use it for stop/start work in the workshop but a tank only lasts around 2 hours.

Another problem I think may be related is when you turn off the ignition, it takes maybe 5 seconds for the engine to stop. As the tank starts to run down, (lower pressure?) the engine stops quicker.

Anyone have any ideas?

 

[OFF]

Normally an LPG forklift running hard (loading trucks) will get a full 8 hour shift out one (33lb) tank.

In my experience, how long an engine runs on after you shut the ignition off is all related to idle speed. Does it idle faster when the tank is full?

After first checking all connections for leaks, my next step would be to rebuild or replace the lock valve - (common one here is called an Impco VFF30) and the regulator (common here is Impco Model J). If these units haven't been done for a while, they'll be all gummed up and usually that's usually the cause of a rich mixture. After that, it's the mixer (carburetor) for a re-kit. There is also a large "screw" on the side of the mixer body that adjusts fuel mixture. With it rev'd up with a load on it (brake stand) screw it in until the engine stumbles and loses power. Then just go out enough for it to smooth out.

 

[Cmark]

Thanks OFF.

I've not noticed any change in idle speed. We'll check out the things you mention.

 

[willie59]

I agree with the things OFF said, and add a few other things. Someone may have put the wrong vaporizer/regulator on it as well making it run rich. And as OFF stated, propane systems are bad about getting gummed up inside, maybe it's some kind of oil in propane used to lubricate pumps, beats me, but it will sure muck up the inside of a vaporizer.

I have seen units that don't use a vacuum lock off valve, if yours doesn't have one, you could always fit an inline electric solenoid lock off valve wired to the ignition circuit to shut off the propane when key is turned off.


http://www.pngtechnologies.com/Electric_Solenoids.html

 

[SFSRACING]

Sounds like it may have an electric lock off on it now, could be wired wrong, maybe fix with a diode. The old lock offs work off vacuum.