Howdy Folks. I'm new to this forum, but have been baggin sand for a while. I bought a 311B last Nov. with 4800 hrs on it. Not a bad little rig for what we paid for it. Pretty sure it came from across the pond as under the Cat Yellow it was painted Red, and had a Dozer Cutting Edge welded across the Bucket Teeth. Anyhow I've put 60-70 hours on it since we got it and today it did this weird thing where it won't idle down, (on it's own) or with the dial switch, and it won't turn off with the key switch. So there it sat running full bore, me scratchin my head tryin to figure out what's goin on. I finally took an adjustable wrench, fit it to the size of the throttle piece the cables hook to and pulled it back till it idled down and finally shut off. Turned the key off and waited maybe a minute to restart....started wide open. Can't have that! Up until now, it ran like a champ, started good, no problems. Don't use a drop of oil, and pretty good on fuel. Anybody had a similar issue. I looked back through older posts but couldn't find the idle down problem. Thanks in advance. Cub
Hi Cub, I have had throttle problems with my machine, but it is a 312B L (probably the same controls as the 311). My throttle problems were different from yours. Nonetheless, this is what I would do, and the following is based on the assumption that your 311 matches my 312: 1) Ask a fourm member to send a wiring diagram for this machine. Serial number will be needed. 2) As you turn the speed dial in the cab, does the numerical readout (1-10) change with it? If not, perhaps a wiring or computer problem. 3) Check to see if the throttle control will work in manual mode (two switches on the back of the RH armrest. One switch toggles between manual and auto (computer controlled)mode, and the other switch bumps the engine speed up or down when in manual mode). If the governor is not working, check to see that the cables are not seized. 4) Check and clean the engine speed sensor. It is mounted in the bell housing on the injection pump side of the engine. take it out and clean it, as it gets dirty from time to time. There is a certain reinstallation procedure (screw it back in by hand untill it makes contact with the flywheel, then back it out 1/2 turn or something like that) but I'm not certain of what it is. The engine speed sensor feeds info to the computer to control lots of things on the machine. If it is getting a bad reading, you may have other things acting up?? 5) Inspect the wiring harness all the way from the governor (mounted above the pump) to the controls inside the armrest. If you get the wiring diagram, you can identify the wires related to engine speed and shutoff and run continuity tests. My problems were caused by rodents that chewed through some wires under the floorboard. There are some tight spots under there (drop the inspection panels from underneath). Hopefully your problem will be that simple. Good luck.
Hi dirtdobber1. Thanks for the reply. Will get the wiring diagram asap. The numbers on the display change, but the rpm's do not, runs wide open and won't shut down with the key switch. The toggle switches on the R armrest have no effect. The cables appear to be fine, free and workable. I called Cat yesterday and they sent me a Governor Actuator Calibration pdf. Can't wait to get into that nightmare.......think I'll start with simple, fuses, connections, etc. I got a friend who's pretty savvy with equipment coming over first of the week to look at things. Hopefully, it's something simple. Keep you posted. Thanks again.
I have a 311b That I got a few months ago and I noticed something the other day that may help your diagnostics. On the display where your feul level is and whatnot, the three buttons that you decide what you will be doing with the machine (loading, digging and grading I call them) have different idle speeds especially the bottom one. Its a long shot but see if changing the mode helps with a computing issue.
Hi Rob. Thanks. I'm willing to try anything. I played with it some yesterday. Took out the speed Sensor and cleaned it, put it back in the same number of turns it came out with. Took the R Armrest apart and checked all connections. All tight and appeared to be ok. Going to check with a meter today to see if internally they're acting right. The engine wont shut down with the key......so it seems to me power isn't getting to the Governor Motor Box to tell the thing to idle down or shut off. I'm guessing here. I've checked all the fuses, but need to check power at the Box. Whatever tells the motor to idle down or shut down, the message isn't getting through. Indecently, when the key is turned to the on position before you go to Start, a "U" appears next to the "number" indicating engine speed top right of the display....Error Code???? Also, before this issue happened, after a normal shut down.....a couple of seconds after the motor had stopped you could hear a mechanical "noise" like an electric motor resetting something, (a short "whurr" of sorts), not the click of a solenoid, but a noticeable noise. It Does Not do this now.........Sometimes this electrical stuff can be mind boggling.
Hello , I have a Cat 312B Sn#6SW00281… The throttle is wide open & not shutting down to idle … The display changes from 1-10 .. The cable doesn’t seem to be melted … Had a helper move the control knob with it disconnected from the injection pump & couldn’t feel it try to do anything also checked the fuse & is good…. The next thing I would like to check is the power to the governor, I believe it has a 6 pin connector …. I’m guessing power & ground then power to the accelerate wire to increase rpm then power on the decelerate to slow down rpm’s … Don’t have a service manual to check the schematic… Thanks again Rob
Check your messages for an electrical schematic.