Forklift with IMPCO CA125 - primary locked in position?

[CamaroMan]

Hi everyone, hopefully ill get some help on this forum. I recently bought a forklift toyota FG9 with a propane setup (3P engine 120psi on all cyls). It ran when bought but needed some real TLC, radiator was hanging loose, wire holding things in place etc - so i decided to give it a good once over to use at my shop.

Im a full time marine mechanic fwiw- but kinda new to the propane thing, im in need of someone who can enlighten me on a few things - see a few pics.

First issue is it seems the carb secondary is blocked off via a base plate, ie only first stage is open, is this common on lpg forklifts? it ran ok and i dont see why it would need the 2ndary opening for a forklift.

Can someone fill me in on the below? This plate sits below the throttle butterflies, firstly the primary is locked via a srew or something, cant really move much, and the secondary is totally blocked off? is this standard for forklifts?





I verified the 12v shutoff is working, it gets harder to start when warm, usually requires full throttle, idles good most of the time. I disassembled both vaporizer and mixer - diaphragms were ok, I did order a new mixer and it seems to be working ok- I just wanted to get it sorted and get everything working well so i can get on with work.

I hope someone can chime in and help me - if the 2ndary is not used then ill take linkage out of the way cos currently its interfering with primary linkage and binding up.. it was seized up but I disassembled everything and freed it up - doesnt look like the 2ndary was every used-

[C3H8]

It was quite common to either lock out the secondary or tie it in together with the primary on forklifts. The primary should still function normally though. Forklifts run fairly low HP and the RPM is governed fairly low. @ barrel carbs were common on gasoline but the engine was way over carbureted. Due to adaptor design some of the 2 barrels were disabled. I can't be 100% sure but that broken plastic piece is either part of the original gasoline system or part of an original propane system that was not of the IMPCO brand. It looks like it could have been part of a spud in system originally.

As for the other part that looks like the mechanism for the governor. Usually they are part of a second throttle body below the carburetor. The plate is usually defaulted to a fully open position when the engine is off. Once started vacuum pulls the plate closed and the spring pressure holds the plate at a specific RPM. The spring and vacuum work in conjunction with each other to maintain the desired RPM. I see an adjuster on the side of the casting that would allow you to change the spring pressure and therefor set the maximum RPM.

It sounds like you are getting too much fuel for the hot starts. The 125 mixer has an adjustment screw on it. Large screw, flat blade screw driver slot with a spring. Turn it out CCW to lean the idle and start up mixtures. Turn it in CW to richen. This screw is an air bypass and bleeds air under the throttle plates to set the mixture. A second area to check is the regulator secondary lever height. If it's too high the mixtures will be richer or the lid may even be pressing on the secondary holding it open a little bit. Set the idle by warming the engine up, turn the idle screw out until the RPM begins to drop. Turn it back in to the best RPM and try a hot start.