Model 630 Bobcat Fuel Supply Questions

[Tigerhaze]

Good morning-
I have a few fuel supply-related questions on a Model 630 Bobcat. I have been having issues with the engine cutting out when getting hot and have read that vapor lock might be an issue. I have checked when hot and am getting spark so don't think that is it. I took the time last weekend to disconnect all of the fuel lines and wrap them with insulation to see if that improves things.
During that exercise I noticed some bare wires exposed on the carb solenoid and the fuel shutoff solenoid so I replaed the portions I could get to with new connectors and wire. I also replaced the fuel shut off solenoid with a new one from Bobcat. After replacement the 630 would turn over but not start- I pulled the fuel line from the pump to carb and no fuel and the pulled the fuel fitting just after the shut off solenoid and turned the key and it appears that the solenoid is not energizing and allowing fuel to leave the tank by gravity. I shoud mention fuel filter is new so don't think it is clogged and it was leaking fuel when I put the new solenoid on.
I have the following questions:
1) I assume that there must be an open on the wiring to the shut off solenoid? Can I just jump 12V to it to see if it opens when energized? The solenoid says 30 watts so wasn't sure if jumping could short it. Also does anyone know where the positive wires to- the ingition switch? The wire it was connected to ran way up in fron of the motor so not sure the connection and the wiring diagram in the parts and service manuals doesn't appear to show it directly.
2) What is the purpose of the carb solenoid? The service manual does not appear to discuss and it seems it wouldn't be a shut off since there is a seperate fuel shut off solenoid. Could it be a cause of cutting out and should it be replaced? Also where does it wire- again didn't see on wiring diagram.
3) The service manual said vapor lock can happen if fuel pump pressure is too low- I haven't checked the presssure as I don't have a guage and tee but with a significant number of hours on the Wisconsin is it worth replacing the fuel pump anyhow and see if that helps?
Thank you in advance.

 

[SkidRoe]

I would definitely be questioning the fuel pump.
I am not real familiar with the 630. Is the fuel tank below the engine or above? If above, does it rely on a siphon action to get fuel to the engine?
My machine had fuel issues right from new, up until I installed an electric fuel pump. Now, no issues.
I believe that the solenoid valve is an attempt to prevent the fuel lines from losing their prime. I say attempt as no valve has zero leakage, and this only deteriorates over time. The solenoid on my machine makes a definite audible click when I turn on the ignition. Connecting the wires of the solenoid to 12 volts and a ground should not hurt it at all.
My $0.02,
SR

 

[Tigerhaze]

I would definitely be questioning the fuel pump.
I am not real familiar with the 630. Is the fuel tank below the engine or above? If above, does it rely on a siphon action to get fuel to the engine?
My machine had fuel issues right from new, up until I installed an electric fuel pump. Now, no issues.
I believe that the solenoid valve is an attempt to prevent the fuel lines from losing their prime. I say attempt as no valve has zero leakage, and this only deteriorates over time. The solenoid on my machine makes a definite audible click when I turn on the ignition. Connecting the wires of the solenoid to 12 volts and a ground should not hurt it at all.
My $0.02,
SR

The fuel tank on the 630 is above the fuel filter, shutoff solenoid, and the fuel lines to the fuel pump; however the carb I believe is above the outlet of the fuel tank (at bottom).
I have contemplated changing out the fuel pump because if nothing else it is original and could have priming or leakage issues in the future. I probably should test it but would need the gauge and tee. My more immediate issue is getting the fuel shut off solenoid to work as that was working before I replaced it with the new one.
Thanks for responding.

 

[Fabricator]

The fuel tank on the 630 is above the fuel filter, shutoff solenoid, and the fuel lines to the fuel pump; however the carb I believe is above the outlet of the fuel tank (at bottom).
I have contemplated changing out the fuel pump because if nothing else it is original and could have priming or leakage issues in the future. I probably should test it but would need the gauge and tee. My more immediate issue is getting the fuel shut off solenoid to work as that was working before I replaced it with the new one.
Thanks for responding.

Might want to take a look through this thread: http://www.skidsteerforum.com/DesktopDefault.aspx?tabid=54&frmView=ShowPost&PostID=27101

Sounds very similar to what I encountered with mine the other year - right down to the buggered wires on the solenoid.

End result was a new (well, new to the 630) coil. Solved all the problems that were plaguing it.

 

[jerry]

The fuel tank on the 630 is above the fuel filter, shutoff solenoid, and the fuel lines to the fuel pump; however the carb I believe is above the outlet of the fuel tank (at bottom).
I have contemplated changing out the fuel pump because if nothing else it is original and could have priming or leakage issues in the future. I probably should test it but would need the gauge and tee. My more immediate issue is getting the fuel shut off solenoid to work as that was working before I replaced it with the new one.
Thanks for responding.

the 630 is air cooled wisconsin engine isn't it? I think the fuel solenoid is there just for safety and you still have the manual valve on the tank base don't you? Never seen a wisconsin with a solenoid on the carb though, are the cooling fins clean and under the carb in the valley dirt collects and holds heat. The electric pump is a good idea also.

 

[Tigerhaze]

the 630 is air cooled wisconsin engine isn't it? I think the fuel solenoid is there just for safety and you still have the manual valve on the tank base don't you? Never seen a wisconsin with a solenoid on the carb though, are the cooling fins clean and under the carb in the valley dirt collects and holds heat. The electric pump is a good idea also.

Thanks for all the replies.
The engine is an air-cooled Wisconsin 4 cylinder, 28 HP (VH4D).
I bought a new coil, cap, and rotor and had not had time to put on but should give a try.
The fuel shutoff solenoid is for safety during operation- there is a manual petcock valve on the tank.
There is a solenoid on the carb- it was installed factory because it is in the parts manual. However the service manual nor parts manual describe what it does.

 

[Fabricator]

Thanks for all the replies.
The engine is an air-cooled Wisconsin 4 cylinder, 28 HP (VH4D).
I bought a new coil, cap, and rotor and had not had time to put on but should give a try.
The fuel shutoff solenoid is for safety during operation- there is a manual petcock valve on the tank.
There is a solenoid on the carb- it was installed factory because it is in the parts manual. However the service manual nor parts manual describe what it does.

So, have you gotten it running yet? Or still looking for solutions?

 

[Tigerhaze]

So, have you gotten it running yet? Or still looking for solutions?

I've had a number of things going on, so just got a chance this weekend to work on the 630.
I found out that the shutoff solenoid (external to the carb) is not being energized when cranking. I disconnected the fuel line between the solenoid and carb and was not getting flow when cranking. I then took of the solenoid and was getting free flow from the tank so the tank and filter are not the issues. I then took off the solenoid and energized it to 12V and am getting flow when energized and shutoff when not, so it is working properly. I am guessing that the wiring between the solenoid and ignition switch is shorted.
Because the wiring runs way up behind the engine I can't tell where the wiring is shorted. I am thinking about replacing the wiring, and am thinking that instead of wiring through the ingnition switch that I could run it through a push-pill switch near my seat. That way I could have a true "emergency shutoff switch" if tipped. Does anyone see any issues with wiring positive and ground straight to the battery (with a suitable fuse) rather than through the iginition switch? The only issue I see is the 30W max wattage stamped on the solenoid, but not sure that matters whether run through the ignition switch or not. Anyone know?
On another but related note, I found out the issue with fuel stavation to my M610. The fuel filter had plugged, starving the fuel pump and everything after it. It was a fairly new filter so I must really have some dirt or rust in the tank. I installed a new see-through filter so I can monitor how quickly it becomes plugged in the future..