Cummins engine not shutting off

[gml]

First let me say that I'm very thankful for all the people who have helped me solve my previous problems and hope that the solutions can be of help to other persons experiencing similar problems. Thank you.

I tried searching this forum but couldn't find anything directly related to this (although seems to be a usual problem in general) so here goes:

1) Cummins diesel B5.9 (1994 or 1995) in Holiday Rambler 1995 (Oshkosh).

2) Engine starts perfectly and the fuel shutoff valve ("stop solenoid" seems to be working), that is it's pulling up to open the valve.

3) When turning key from run to off the dashboard electricity is turned off but engine remains running.

4) Shutoff valve is still in open position so here seems to be the problem. When I manually close it the engine stops.

5) I just now measured the voltages in the harness (black-ground, white-pull up, red-hold up) and while I unfortunately couldn't measure the start voltages it looked likes this:

Key = OFF: Pull up 0.0V, Hold up 0.0V
Key = RUN: Pull up -0.4V, Hold up 11.70V

I realize the battery is pretty low (charging at the moment) but any suggestions?

Q1: How exactly is that stop solenoid supposed to work? Shouldn't it automatically go back with spring power to valve = shut when there is no electricity coming from the wires so bad ground etc should rather prevent the valve from opening than closing? Could the engine+alternator running in some way be generating electricity to energize the solenoid because of some connection error somewhere?

Q2: The Dodge owners with same motor seem to have this problem and the main suggested fixes are 1) Don't replace the solenoid (well, I did that, the old was in pretty horrible shape anyways ) 2) Check the blue cable going to the battery and 3) Replace the relay, so where would I be looking for these in my HR and () what does that relay look like?

Picture of my new (and expensive) fuel stop valve installed

[gml]

Ok, everything started working as expected with a (more) fully charged battery.

Could someone explain to me why this might have been the problem?

[tom chelbana]

Maybe your problem was a low voltage problem from a under charge battery?

[gml]

Originally Posted by tom chelbana

Maybe your problem was a low voltage problem from a under charge battery?

It seems possible but I would be really interested in learning why the low battery is affecting the shutoff since the non-energized state of the shutoff valve is to stop fuel flow?

[dieselbeaver]

Sorry to hear about your issues,

First things first -- charge the batteries.

Second - it takes voltage to hold the shut down solenoid up. So the issue is most likely on the coach side. As it looks from the picture that this isn't a 2010 model I would start by making sure the ignition switch is indeed interrupting the power to the proper terminal at key off. If that is ok, then you really have to start looking at the chassis wiring. There is normally a relay controlling at least the pull in side of the shut down, locate and check the circuit out there.

The way that unit works is that the pull in coil takes quite a bit to pull the lever up (hence the relay - most of the time) and the hold in coil is a low amp draw... So as you turn the key from off to on then to ignition you energize the pull in coil circuit via a relay ( I hope) then as the armature is pulled to its full in position the hold in takes over and as you release the key back to the on position the hold In maintains the armature in position unti such time as you turn the key again back from on to off- at which time the magnetic field collapses letting the armature be pushed back by the internal spring pressure and pulled by the shut off lever spring tension and there for putting the fuel rack in the no fuel position.

So based on what you have said I can say with some level of confidence that your issue is most likely on the chassis side at the above listed areas. Basically it is much, much less likely that the new solenoid is sticking in the run position versus the chassis wiring not killing power to the hold in coil at the appropriate time.

But really to troubleshoot any electrical problem there has to be sufficient system voltage available. Charge the batteries and start looking the rest of the system over starts no at the key switch.

Hope it helps,

Allen

[gml]

Originally Posted by dieselbeaver

Sorry to hear about your issues,

First things first -- charge the batteries.

Second - it takes voltage to hold the shut down solenoid up. So the issue is most likely on the coach side. As it looks from the picture that this isn't a 2010 model I would start by making sure the ignition switch is indeed interrupting the power to the proper terminal at key off. If that is ok, then you really have to start looking at the chassis wiring. There is normally a relay controlling at least the pull in side of the shut down, locate and check the circuit out there.

The way that unit works is that the pull in coil takes quite a bit to pull the lever up (hence the relay - most of the time) and the hold in coil is a low amp draw... So as you turn the key from off to on then to ignition you energize the pull in coil circuit via a relay ( I hope) then as the armature is pulled to its full in position the hold in takes over and as you release the key back to the on position the hold In maintains the armature in position unti such time as you turn the key again back from on to off- at which time the magnetic field collapses letting the armature be pushed back by the internal spring pressure and pulled by the shut off lever spring tension and there for putting the fuel rack in the no fuel position.

So based on what you have said I can say with some level of confidence that your issue is most likely on the chassis side at the above listed areas. Basically it is much, much less likely that the new solenoid is sticking in the run position versus the chassis wiring not killing power to the hold in coil at the appropriate time.

But really to troubleshoot any electrical problem there has to be sufficient system voltage available. Charge the batteries and start looking the rest of the system over starts no at the key switch.

Hope it helps,

Allen

Thank you Allen!

As I mentioned above, after charging the battery it actually worked. I started and shut down the engine several times and the only thing I noticed was that the engine didn't start stopping immediately after turning the key to off but it took half a second for that to happen (compared to manually closing the shutoff valve which, I felt, immediately closed the engine).

I guess I could chalk this up to too empty a battery but it would be really nice to understand why low voltage (or bad ground) would prevent closing the valve. Is there some part of the system (relays?) that can prevent the hold current from switching off because it defaults to wrong state without enough voltage?

[Buford B]

Just to be sure, disconnect the solenoid mechanically from the linkage. Check that the linkage moves freely. It could be sticking???

[jamboree89]

Agree with Buford B check that the fuel linkage moves freely.