Kalmar C50:
Forklift runs rough at idle

I have a Kalmar C50 forklift. It has a impco ca55 carb and impco kb mixer.

It runs rough at idle.

Here's the description of the problem:

1) Kalmar C50
2) Nissan Engine
3) Impco ca55 carb and impco kb mixer/vaporizer
4) After a day of sitting, it is hard to start
5) Once it starts, it runs rough at idle and often dies when put in gear without pushing on gas first
6) Generally after I push the gas pedal, it runs strong
7) With gas pedal pushed all the way, if I engage tiltback, the engine does not die but slows down (proper response).
8) When it starts running rough at idle, it may even die by itself
9) When it starts acting up and run rough, if I press the PRIME button on the vaporizer, it straightens itself out and runs good for as long as the prime button is pressed
10) There is proper antifreeze level
11) I tried adjusting idle mixture with idle mixture adjusting screw, unfortunately result was no different
12) I took out the air filter (which was very dirty), with no change in idle performance
13) Again, with gas pedal pushed, it hesitates to speed up, but speeds up and runs very strong.
14) The vaporizer is heating properly with warm antifreeze, with no frost forming on it.

I am suspecting the vaporizer unit, however I would like to see what you guys think.

I am specifically interested in a troubleshooting procedure, as opposed to part swapping. I have a lot of forklifts and want to learn how to work with propane systems.

I have various pressure gauges that I can hook up.

Any suggestions on where to begin isolating the problem?

Thanks a lot!
  • Posted 8 Dec 2014 13:06
  • Modified 8 Dec 2014 13:12 by poster
  • Discussion started by ichudov
  • Illinois, United States
Showing items 1 - 7 of 7 results.
Kevin, thanks, I will double check again tomorrow with a good flashlight. I thought I saw "KB" on the vaporizer, it may not be the original unit.

I will try to put some low pressure gauge to see how pressure behaves with and without load, and idle or governed speed.

I will post an update,
  • Posted 8 Dec 2014 14:13
  • Reply by ichudov
  • Illinois, United States
Should be a plug in the vaporizor,probably a 1/8 pipe plug......put a pressure gauge in there,should run around 2 PSI check at idle and at full throttle and in tilt bypass see if it is dropping.......are you sure this is a KB impco vaporizor??? That modl,dosent sound familiar,am thinking it is either a model,J or a COBRA???
  • Posted 8 Dec 2014 14:07
  • Modified 8 Dec 2014 14:08 by poster
  • Reply by kevin_t
  • Pennsylvania, United States
Thanks, it is great to talk to someone with experience. I just want to learn something so I can troubleshoot those things in the future.

What, in this case, would make me think that it is the vaporizer?
  • Posted 8 Dec 2014 13:59
  • Modified 8 Dec 2014 14:06 by poster
  • Reply by ichudov
  • Illinois, United States
15 YEARS EXPERIENCE!!!!
  • Posted 8 Dec 2014 13:52
  • Reply by kevin_t
  • Pennsylvania, United States
EXPERIENCE!!!!
  • Posted 8 Dec 2014 13:52
  • Reply by kevin_t
  • Pennsylvania, United States
Kevin, how do you know that the vaporizer needs to be rebuilt? What line of thinking led you to this conclusion? Thanks
  • Posted 8 Dec 2014 13:47
  • Reply by ichudov
  • Illinois, United States
Sounds like the vaporizor needs rebuilt....wouldnt be a bad idea to rebuild the ca55 at the same time.
IF you have no experience with propane sytems them it would be best if you had a forklift tech from your local repair dealership do the work,not doing the job right can cause a fire and or injury or even death to someone......
  • Posted 8 Dec 2014 13:44
  • Reply by kevin_t
  • Pennsylvania, United States

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