| Author | Message | ||
| Andrew Bowey (All2go)
Registered Member Username: All2go Post Number: 22 Registered: 12-2006 Posted From: 72.148.201.161 Rating: N/A |
I always started my 1973 GMC 4905 with the neutral start over-rule switch because after she warmed up I would shut down , put her in first ( spicer) and then restart her and off we went. A couple of days ago when trying to start her she turned over about three times and then was just silent. absolutely no response from the switch, no clicking... no noise at all. After cranking her from the rear switch I thought there was a bad connection in the drivers panel switch. I tested the switch and it works fine, power in and when activated power out. The engine over-rule switch I used is on the side drivers panel, I never ever bothered with any of the other switches. there is also an engine over-rule switch on the dash panel along with an engine start switch and an engine run switch and an engine emergency stop switch... too many switches, but they all have their purpose I suppose. Eight months ago it was a loose ground connection. Now she will start with the rear start switch sometimes and sometimes with the engine start switch up on the dash panel, but not with either of the over-rule switches on the dash or side panel. this means I cannot put her in first gear and start the engine. The piston on the engine stop air cylinder will also not stay retracted. when I can get it to retract it pops back out after a time delay and prevents me from starting the engine sometimes. it does not activate once the engine is started to shut the engine down unless I flip the switch to activate it. it works normally then, but when the engine is off it just pops out on it's own after a minute or two after I have used the run/stop switch in the rear to retract it. I am guessing she is fitted with some sort of time delayed shut down? Is this something wrong with the neutral safety switches? I can't figure out what the problem is. Can someone please give me an idea what to try next to diagnose or solve whatever is wrong? On the occasions she will not start at all I have to wiggle the gearshift lever and then sometimes she will start with the dash engine start switch. when put in first she will not start at all, even with the over-rule switch. I'm lost trying to figure out why she will crank sometimes, and then not crank at all sometimes. always with either the rear start switch or the dash start switch, and only if I am quick before the engine stop cylinder piston pops out.... but never with the over-rule switch like she always used to. Any ideas how to get her started and into first gear? | ||
| Cory hart (Chart1)
Registered Member Username: Chart1 Post Number: 21 Registered: 1-2010 Posted From: 67.184.212.122  Rating: N/A |
Wow that sounds complicated, But I had a similar situation on my mci sometimes it would start and sometimes not sometimes rear switch sometimes front. It ended up being nuetral saftey switch. My shifter was not in the right position to signal the nuetral safety switch. I found it by moving the shifter while pressing the start button at the same time. Good luck these things can be very mind boggling, but I am sure with all the great minds on this board someone will have a solution to your problem. | ||
| Andrew Bowey (All2go)
Registered Member Username: All2go Post Number: 23 Registered: 12-2006 Posted From: 72.148.201.161 Rating: N/A |
That was what I thought because when it does not start there is a click now like a relay energizing. The engine stop air cylinder is not the problem because the engine will not even turn over. The starter is not being energized. The dash over-rule switch does retract the engine stop air cylinder because I wedged the switch on while I went back and looked at the stop air cylinder. There is also no click when the over-rule switch on the driver side panel is used to try and start the engine. Now it does not start at all with any switch. Thanks for your input Cory. | ||
| Buswarrior (Buswarrior)
Registered Member Username: Buswarrior Post Number: 1822 Registered: 12-2000 Posted From: 76.68.134.55  Rating: N/A |
Perhaps all this needs to be removed/rewired/bypassed? Simplify, fresh wiring, ignition switch and starter switch and be done with all the messing around. You routinely bypass the stuff anyway, so just wire it that way? A warning on the rear panel that there is no neutral safety should take care of the busnut who inherits your coach. happy coaching! buswarrior | ||
| Mark R. Obtinario (Cowlitzcoach)
Registered Member Username: Cowlitzcoach Post Number: 207 Registered: 4-2001 Posted From: 173.152.197.236 Rating: N/A |
I agree with buswarrior. You need to start from scratch on your bus starting circuit. You have so many places where an intermittent glitch can occur that it might not be possible to determine for sure where the gremlin is living. And it is always smart to make sure the main cables from the battery are in good condition with good contact points. I have seen cables that appeared to be in good condition on the outside that were solid green underneath the insulation. I have also seen good cables that weren't getting the job done because the grounding point wasn't very good. Good luck and keep us posted as to your progress. | ||
| Andrew Bowey (All2go)
Registered Member Username: All2go Post Number: 24 Registered: 12-2006 Posted From: 72.148.201.161 Rating: N/A |
Thanks Buswarrior, that's a good solution. How does one cut out all the gizmos that stop the bus from starting in gear? If you tell me where to run a wire from point "a" to point "b", and which other wires to disconnect to get the starter energized... and crank the bus in first (with the clutch depressed of course), I will post the "no neutral safety sign" and be as happy as a pig in you know what. That is a great idea, now can you help me implement it with more detail? Mark, what you say is very valid for 37 year old wiring, I will do my best to verify what contacts I can, clean it up and keep trying. Thanks. |