Hi

I am working on what I believe to be a mid 2000s Clark CMP30, though I am unfortunately uncertain on the model number.

The forklift has 8300 hours on it and has been operating in an extreme manufacturing environment for the past few years so any model numbers or plates containing that information are worn off and / or covered by grime.

I'm quite sure the engine is a Mitsubishi 4G64 with propane EFI. It runs and drives normally (no misfires or anything like that) but it runs rich enough that there is a constant fowl smell from the exhaust and increased propane consumption.

To start, the oxygen sensor was replaced to no avail (even when allowing the engine to fully warm up).

I have done my best to test some other sensors including the 4 pin sensor on / just below the throttle body, as well as the 2 pin sensor near the throttle body on a hose canister, but all show power and the 2 pin sensor shows a change in voltage when using the throttle with the engine running. The 4 pin doesn't seem to change when running the engine, however unplugging it causes the RPMs to drop and eventually a stall. To clarify though, this is not the connector to the throttle body / butterfly itself as this sensor is slightly below that.

The air filter will be getting changed soon, however removing it and running the engine makes no difference in exhaust smell or RPMs.

As a last resort option, I have considered the possibility of a dirty throttle body but with my lack of knowledge in this area I was hoping to hear from someone more experienced with this configuration before I spend more time working on it. The forklift has plenty of power once the computer sees that it has warmed up though, so that starts to point me away from a throttle body problem.

I am by no means a certified forklift technician, but I know my way around engines fairly well, especially carbureted ones. However, propane EFI on top of the lack of on-board-diagnostics on this truck have got me scratching my head.

Any tips or clues on where I can look would be greatly appreciated.

Kevin