Skip to main content ↑ ↓
Topic: unplugged wire (Read 801 times) previous topic - next topic - Topic derived from Coolant Filters

unplugged wire

I'm in the process of replacing the fuel shutoff solenoid on my C8.3 Cummins. I noticed a wire  with a stab-me female terminal that was unattached and having nothing to do with the shutoff unit. Close enough to be where it should attach was a male stab-me terminal on what looks like the back of a switch mounted on the top of the engine about 1/3 from the front. Now the question: apart from the shutoff unit the coach has been running with no problems. I'd had work done on the brakes and fuel pump at a Cummins shop in Illinois a month ago. Do I plug the wire in and see what happens? I can't find anything in the wiring diagram to help me.

Re: unplugged wire

Reply #1 –
Your choice, if every thing is working I'd leave it alone.

Re: unplugged wire

Reply #2 –
Do you have a Pac Brake?

Re: unplugged wire

Reply #3 –
A photo of the "switch" showing its location might be helpful in identifying it.  When you say "mounted on top of the engine" do you mean the switch is attached to the valve cover?  I don't recall seeing any electrical stuff on mine - I'll go out and look later...

Re: unplugged wire

Reply #4 –
No PacBrake. Switch is attached to engine with one connector soldered down. If I knew how to get photos from my phone to the Forum I'd include one.

Re: unplugged wire

Reply #5 –
How about the wire code? Still visible?

Pierce

Re: unplugged wire

Reply #6 –
Can't see a number on the wire. It's about 22 ga. and hooks to a solenoid. there is an insulated pipe from the front side, about 3/8" and then a Tee from the back side with a couple of 1/4" uninsulated pipes. I can't find where they go. This isn't on the rocker cover but right nest to it on the center of the head. If I were twenty years younger and 100 pounds lighter I might be able to  chase some of the numbers down.

Re: unplugged wire

Reply #7 –
Our similar engine has an intake manifold heater with wire connections, also a solenoid that controls fuel flow into manifold during 'wait to start' pre-heat sessions.
FYI, we use Photo Transfer app to wireless transfer smartphone photos to our computer, and it works great...

Re: unplugged wire

Reply #9 –
I think I've got the photo thing figured out. Thanks to Pierce for the PhotoSync suggestion, that works fine.

This is a solenoid. I don't know why I wrote that it was a switch. With the  pipes in and out I believe that is does have something to do with the fuel system. If that is what it is, what's the harm leaving it unplugged or do I re-hook it up?

Got the new fuel shut-off solenoid installed and the engine starts like it should but then drops out like the ignition was turned off. I was at the back and thought the DW had started it and then shut it off. It only stays on for about five seconds then shuts off.

Really stumped.

Re: unplugged wire

Reply #10 –
Does the fuel shut off solenoid drop out when it shuts down.

Re: unplugged wire

Reply #11 –
As I recall, the fuel shutoff solenoid has two stages of operation.  The initial stage is a "higher" voltage signal that pulls the solenoid rod up.  The second stage is a lower voltage signal that "holds" the solenoid rod in the up position, until the ignition switch is turned off.  Then the rod drops and the fuel shuts off.

Sounds like your solenoid might be pulling up, but not holding.  Should be 3 wires going to solenoid.  One is ground, one is "high" voltage signal (only when starter is energized), other is "low" voltage signal (only when ignition switch is in "RUN" position).  Check with multimeter?

Re: unplugged wire

Reply #12 –
OK, found a wire at the remote start switch that was pulled loose and then touching the metal bracket. Separated that and all is well.

Had the coach worked on at a Cummins shop and they managed to pull most of the wires loose from the remote panel. Will address that when I get to Florida and a month. If these guys would watch where they are crawling around this kind of thing wouldn't happen.

I left the "unplugged wire" unplugged. Bruce is right, if it works then leave it alone. Not sure if that will cause a problem down the road but I suppose that's part of the adventure.

Thanks to all  ^.^d

Re: unplugged wire

Reply #13 –
The cold weather start aid maybe partly inoperative without wire to fuel injection solenoid, which may show up on a cold morning causing harder starting.  It could affect how "wait to start" works.

There is a wiring diagram showing the intake manifold cold starting aid that could help.

Fuel shut off wires are:
1) ground
2) pull-up coil higher amperage 12-volts from starter (live only during cranking)
3) hold-up coil lower amperage 12-volts from ignition (live when ignition is on)
Either above 12-volt connections will allow fuel to flow to injector pump.
Without either 12-volt connections, fuel solenoid turns off and shuts down engine.
 

Re: unplugged wire

Reply #14 –
Cold mornings...to us that would be anything below 60. Not sure what the coach would think was a cold morning since it has been so long since she's seen one of those.