I have a 2005 bobcat s175 that wont start. What i found out is that the fuel shut off solenoid is not opening. I bought a new one and it seamed to work for a few days but now im back to the same prob with the solenoid out bobcat starts and runs great. I checked the fuel fuse and it is good i switched the fuel relay with a different one and still doesnt work. When you turn the key on with the fuel relay out there is power to where the post that is turned a differrnt way plugs in but none of the other terminals have power. I would think there should be a trigger wire to make the relay work it doesnt click so i would say its not working. All three wires going to the solenoid are grounded when checked. The solenoid does work when hooked up to a battery. Is there any other safety swich that might not be working that is not letting the relay work. There is no power to any of the three wires going to the solenoid with the key on or off. Any help would be great. It seems this might happen when its really cold out but that could just be by chance.
The fuel solenoid on Bobcat machines is controlled by the ECU. The three wires at the solenoid (not the Bobcat harness wires) are red, black, and white. Red is the hold coil inside the solenoid, black is ground, white is the pull coil inside solenoid and can only have power for a few seconds or it will short out. When you power up ignition, the ECU does two things, it sends power to the red wire (hold coil) and it powers up the fuel relay in the fuse box. When the fuel relay is activated, it relays battery power to the white wire of the solenoid. After a few seconds, the ECU takes power away from the fuel relay which disconnects battery power to the white wire at solenoid. By that time the solenoid has had time to engage and the red and black wires hold it engaged.
Maybe I need to look at the harnes at the ECU because with the key on there is no power geting to any of the wires. In the cold there sometime is a prob with electronic parking brake that has the same color wires going to it black white and red. The brake won't disengage when it's realy cold. I switch the relay and it seems to be working now. I'm not trying to get side tracked just thought maybe they had something to do with each other. Where is the ECU on the s175. Does anyone have a wire diogram so I know where to follow the wires to. Thanks for your help.
The parking brake solenoid works the exact same way, controlled by the ECU in the same manner as the fuel solenoid. I'm not sure what's causing your problem as I've never ran into this, both fuel solenoid and brake solenoid acting up, even in cold temps. I just know how Bobcat controls them as stated previously. As for the ECU, if you're sitting in the seat, the ECU is located behind the panel to the left of your left foot. The only thing I could advise would be check your wiring harness closely looking for rubbed spots, it's a common problem on Bobcat machines the way the harness has to be routed over various machine components. And it's not an easy task to check all of the harness the way it's routed. As for the diagrams, you should be able to go to Tradebit website and download a service manual for your machine for very little money.
The fuel cut solinoide wire connection is a lot of times bad.... Do you have a wiring diagram? You should have power at the connection at the rear by solinoide ... To open cut off solinoide I have the same issue and had the machine tore down to the ecu. Did continuity tests. Found broken wire in the rear of machine close to the connector to the fuel cut of solinoide so I just cut it back and hard wired the solinoide in... Worked great. Let us know how you work out...
Today when I got out of work it was a little warmer out so I did a little more checking out. I pulled the fuse block out and when I put power to the tan single wire of the fuel relay the solenoid opens then closes when power is taken away. I also unplugged and reconectrd the ecu plugs everything looked good there. I started the bobcat with solenoid out and a cover over the opening when I went around to the rear the solenoid is working. I guess you have to turn the key to crank the motor over to get power back to the solenoid I have been testing everything with just the key turned to on. So now I have no idea why it doesn't start when it's really cold but if the solenoid is removed it fires right up. Would the cold like around 14F make the solenoid not work. Or it could have been a lose conection somewhere. Thanks for you ideas I'm not convinced it's fixed things don't just fix them selfs.
Interesting thoughts Dave, I've never really tested this circuit, but you may be right, the ECU may not power up the fuel solenoid until you hit start. Which would make sense, this gives time for the glow plug relay countdown before you crank the engine. I'm going to have to check that out so I'll no better how the fuel solenoid program works.
I also noticed that it looked like water got into the fuses and relays. I cleaned the conections on the relays and fuses this could have also been the prob with the fuel solenoid and also for the parking brake solenoid. I will have to keep trying to start the bobcat when it gets cold here again in a few days.
Today was about 19F out so I went out to see if the bobcat would start. It did start with no prob. I think my prob could have been a conection at the relay or it could have been the relay it self. I switched the relays around don't remember witch one was orig was in the fuel spot. Today the parking brake worked fine also but the front and rear lights didn't work at first but came on after about 3 min of the bobcat running. Maybe those 2 relays were in the fuel and brake places to begin with and maybe they stick in the cold. Just my thoughts