Engine won't shut off w/ignition key

[Brad Burgess]

Hello All

Had this problem once when I picked up the coach from the seller.  Now it happens half the time.  Anyone else have this issue and if so, what is the cure?  Engine is 400HP C9.

Thanks, Brad Burgess

[Richard And Babs Ames]

Your fuel cut of solenoid is not shutting off the fuel supply to your engine. Can be as simple as a loose/bad connection or ground to a faulty solenoid.

[Jeremy Parrett]

My C12 would not shut down either until I switched off the dash a/c. !!!!!   I think it is an engine ground issue. There is a ground stud on the C12 cylinder head that is mentioned in the service docs that has to be cleaned regularly,as well as the main ground stud on the starter motor .  

[Keith Oliver]

On mine it is the headlight switch.  If I remember to always turn the headlights off first, the engine always shuts down with the key.

[Brad Burgess]

Hello All
OK, new info.  In desperation (and knowing that you are not supposed to do this) I turned off the battery disconnect switches.  Turned off the chassis battery - still running.  Then turned off the house disconnect (chassis still off) and, after a couple of surges, the engine stopped.  Can anyone help me with what this might mean?

Thanks,

Brad

[Robert Mathis]

It's definately your fuel shutoff solenoid. Check the wires both hot and ground. There should be a little lever on the solenoid itself that you can move to shut it off manually. The solenoid is in the fuel line.

[Edward Buker]

Seems like there is a voltage sensitive stuation when a variation of switched accessories causes the solenoid circuit to work in some coaches. The suspicion is that there is a poor connections somewhere. It may be worthwhile to add a couple of sense wires to the fuel solenoid that can be tie wrapped and led to the engine hatch with some spade terminals on them for sensing and applying voltage or ground to enable an emergency means of shutting down if the solenoid shut off unit is working and this is caused by a wiring issue.  One could put a switch in place to enable an alternate ground or a + if need be to kill the coach. At a minimum this would help diagnose the problem by seeing what voltage is applied when it works and when it does not or adding a redundant ground and see if that kills the engine. The solenoid may pick up its own ground from its mounting location and you may have just a + wire on it to work with.

When you cut chassis power and then house 12V power you may have shut the solenoid down, shut off the fuel pump, disabled some of the engine monitor systems and had the computer shut the coach down, or the alternator voltage with no battery load may have gone high and if it lost the regulator may have finally stopped all voltage/power sources killing the engine. It is hard to know which system caused the shut down. Because of the surges it was not a standard sharp fuel solenoid shut down. I know this was an emergency shut down situation and you did what you had to do, hopefully no damage was caused. Hope you can find the cause before it happens again.

If you can get a voltage measurement on the solenoid lead in the accessory position while it is still connected to the solenoid that should be the fuel off voltage reading. If that is something much less than 12V (assuming powered is the off solenoid position) that may be your problem. In that case I would definately add a 12V fused source wire with a switch to manually be able to bypass the coach wiring to shut down until I could get the wiring sorted out. If I saw approximately 12v I would consider having the solenoid valve changed to eliminate the solenoid being the issue. Hope this helps.

Later Ed

[Ken Sair]

We had the exact same problem with our C9 in a 2007 Beaver Contessa. Turns out the culprit was the Monaco wiring for the US Gear toadbrake. Our coach would not shutoff when the toad was attached and plugged into the coach. Worked fine with no toad. Something to do with feedback. The difficult solution is some wiring work. The easy solution was to install a Diode in the toad so power did not feed back into the coach.

I think a phone call to Monaco Tech Support migh send you in the right direction.

Ken Sair 2007 Contessa

[Ken Buck]

The black "battery" wire on the 7 pole trailer plug must be isolated from return voltage or the 07 Contessa will not shut off as Ken Sair says. A diode is the easiest way to prevent the toad/trailer battery from backfeeding power to the coach. I don't have a US gear toadbrake like Mr. Sair, but ran into exactly the same problem and exactly the same solution while trying to use the pole as a battery tender for the toad.

Ken Buck
07 Contessa