742b hard starting

sshev · Oct 17, 2010

I'm new to this group, so thanks in advance for any advice. I recently bought a clean low houred (1500) Bobcat 742b. Its got the Mitsubishi 4G32 engine. I really like it and it runs well, at least once you get it started and warmed up. Starting it cold is the problem. You have to pump the throttle lever rapidly with it fully choked and eventually it'll pop. After it starts, it takes a long time to warm it up enough so it'll move. Once warm, it idles smooth and runs great. I've replaced the points, plugs and condenser...didn't seem to help much. Carb kit? Fuel filter? Whats the most likely culprit? It does have a hose heater on it, but if it's this hard to start at 50°, I'm really worried about getting it going in an Iowa winter. Thanks

OldMachinist · Oct 17, 2010

Sounds like a fuel problem. Your carb has a sight glass on it to check the fuel level in the bowl, check that the bowl has fuel in it. If the bowl is empty everytime you go to start it the fuel pump has to fill it before the engine will start. A weak fuel pump or clogged filter will take a while to do that. Next I would check the accelerator pump, with fuel in the bowl pump the throttle while looking in the carb throat for fuel spraying. No fuel spray could be ether a bad pump or the check ball is stuck.

jerry · Oct 17, 2010

Also check manually to be sure that the choke butterfly is actually closing completely, the linkage may need adjusting. Had this happen once or twice.

wings5j · Oct 31, 2010

jerry said:
Also check manually to be sure that the choke butterfly is actually closing completely, the linkage may need adjusting. Had this happen once or twice.

I have the same rig. Just cleaning the carburater did a lot of good for mine. I have a soft plug block heater on mine but I don't seem to need it until temps get down around freezing.
The technique described in the operator's manual (I am not at home so just going from memory) is to pump the throttle several times and then place it partly forward with the choke out and apply the starter.
Let us know if you get it figured out.

John

skidsteer.ca · Nov 1, 2010

wings5j said:
I have the same rig. Just cleaning the carburater did a lot of good for mine. I have a soft plug block heater on mine but I don't seem to need it until temps get down around freezing.
The technique described in the operator's manual (I am not at home so just going from memory) is to pump the throttle several times and then place it partly forward with the choke out and apply the starter.
Let us know if you get it figured out.

John

If al else fails get a primer bulb for a outboard (like the diesel Bobcats use to prime the system) and install it in the fuel line, a couple quick squeezes b4 fire up can save a lot of cranking.
Ken