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Old 10-17-2018, 02:00 PM   #11
Bus Crazy
 
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See what the pressure is in the wet tank, the gauges on the dash don't read that. Opening the petcock on it with the bus running is a quick way to tell for air flow/pressure.

After that, find the governor and see if that is stuck causing the compressor not to run.

As far as air pressure and throttle issues, as said by others, the throttle is electronic and is completely seperate from the air system. I doubt the two problems are related.
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Old 10-17-2018, 07:03 PM   #12
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Air systems are not terribly complex ... though they can seem to be. You have:


1. Air compressor (and it's related governor, belt/gears, pulleys, etc.) The function of this is fairly straightforward. The governor's job is basically to turn the thing on/off, typically at 90/120 PSI, respectively.
2. Air dryer (on most systems, a few may not have this). The air from the compressor goes through this. Many have "cartridges" or filters that should be changed about once a year (and rarely are). The most common symptom of a failed air dryer is a failure to build up pressure (and usually accompanied by a very noticeable hissing of air from the dryer). Some designs are proprietary to the vehicle to which it's attached, but so-called universal fit designs work just fine in their place.
3. Air tanks. You'll have at least 1 "wet tank", fed by the air compressor, and at least 2 "dry tanks". Sometimes you'll have 1 tank with 2 compartments, or any combination the builder installed. There is often a "protection valve" which will feed the dry tanks once the wet tank reaches a certain pressure. If a tank looses pressure suddenly, this protection valve maintains pressure in the other system, giving you a chance to stop safely.
4. "Everything else". Air brakes, air-ride suspension, parking brakes (also called spring brakes), air-ride seat, gauges, warning lights and buzzers, brake-pressure sensor (the one that makes your brake lights work), and, you guessed it, everything else. The vast majority of this stuff is past a protection valve, basically meaning none of it will work until the system reaches the protection pressure, typically 60-80 PSI. An air-throttle (if you have one) will be on this circuit. Usually the only thing *NOT* on this circuit is the brake pedal, parking brakes, and gauges/warnings. The brakes *NEED* to work at all times, regardless of how much air is in the system.
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Old 10-17-2018, 08:05 PM   #13
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Year: 1999
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Engine: 5.9L 24V-L6 Cummins ISB
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Quote:
Originally Posted by Tomas View Post
I have a TC1000 with a 5.9L 24V.
Engine starts and idles but there is not throttle. In other words pressing the accelarator pedal won't do a thing.
Front air reads about 40 psi and rear about 30.
I have not been able to identify any air leaks.

Is there a troubleshooting guide I can follow?
What year is your bus? My 1999 TC1000 5.9L 24V will respond to the accelerator pedal with no air in the system (after bleeding the tanks down completely).

Quote:
Originally Posted by cadillackid View Post
gnome,

some busses, generally Rear engine busses with non electronic engines had a throttle that was activated by air pressure.. the way it worked is at the pedal you have an air valve that sends air pressure back to a spring loaded actuator.. the mnore air pressure, the more that actuator essentially activated what would have been the throttle cable. if the bus air brake system pressure was not up then the throttle would fail to operate. there should not be an air throttle on a front engine bus..

Christopher
Are you saying the intake tube was restricted ("throttled") like a gasoline motor has a butterfly-throttle-vavle, or are you saying the fuel injector controls were remotely air-operated? I believe the latter...otherwise why would a rear-engine need to be throttled, but not a front-engine? I totally see a remote pneumatic system for the rear makes sense....


Quote:
Originally Posted by cadillackid View Post
being electronic this one should be an electronic fly-by-wire.. make sure the wiring connector at your throttle pedal is plugged in securely and that none of the wires have been damaged or cut.. these wires should feed into a harness going to the Engine computer.. be sure the engine computer connectors are secure as well..
Christopher
Yea, what he said....
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Old 10-17-2018, 08:16 PM   #14
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Quote:
Originally Posted by Mountain Gnome View Post
What year is your bus? My 1999 TC1000 5.9L 24V will respond to the accelerator pedal with no air in the system (after bleeding the tanks down completely).



Are you saying the intake tube was restricted ("throttled") like a gasoline motor has a butterfly-throttle-vavle, or are you saying the fuel injector controls were remotely air-operated? I believe the latter...otherwise why would a rear-engine need to be throttled, but not a front-engine? I totally see a remote pneumatic system for the rear makes sense....



Yea, what he said....

Gnome - yes air actuated throttle for the fuel pump.. the air tube is unrestricted at all times.. as you say all of a diesel's throttle control is fuel. on RE busses the distance front to back made mewchanical lionkage extremely sloppy and prone to sticking.. so using air elminated this.. the pump was the same.. but the lever which a normnal throttle cable would push / pull. was activated by an air cylinder.. the pressure in that cylinder controlled by the driver'throttle pedal up front..



-Christopher
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Old 10-18-2018, 07:29 AM   #15
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Year: 2002
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Quote:
Originally Posted by Brad_SwiftFur View Post
Air systems are not terribly complex ... though they can seem to be. You have:


1. Air compressor (and it's related governor, belt/gears, pulleys, etc.) The function of this is fairly straightforward. The governor's job is basically to turn the thing on/off, typically at 90/120 PSI, respectively.
2. Air dryer (on most systems, a few may not have this). The air from the compressor goes through this. Many have "cartridges" or filters that should be changed about once a year (and rarely are). The most common symptom of a failed air dryer is a failure to build up pressure (and usually accompanied by a very noticeable hissing of air from the dryer). Some designs are proprietary to the vehicle to which it's attached, but so-called universal fit designs work just fine in their place.
3. Air tanks. You'll have at least 1 "wet tank", fed by the air compressor, and at least 2 "dry tanks". Sometimes you'll have 1 tank with 2 compartments, or any combination the builder installed. There is often a "protection valve" which will feed the dry tanks once the wet tank reaches a certain pressure. If a tank looses pressure suddenly, this protection valve maintains pressure in the other system, giving you a chance to stop safely.
4. "Everything else". Air brakes, air-ride suspension, parking brakes (also called spring brakes), air-ride seat, gauges, warning lights and buzzers, brake-pressure sensor (the one that makes your brake lights work), and, you guessed it, everything else. The vast majority of this stuff is past a protection valve, basically meaning none of it will work until the system reaches the protection pressure, typically 60-80 PSI. An air-throttle (if you have one) will be on this circuit. Usually the only thing *NOT* on this circuit is the brake pedal, parking brakes, and gauges/warnings. The brakes *NEED* to work at all times, regardless of how much air is in the system.
Thanks for the explanation.

Let me see if I understand how its plumbed correctly. From the compressor to the governor to the wet tank. From the wet tank to the drier and from the drier to the front and rear "dry" tanks. Is that correct? I thought I saw a hose going directly from the governor to the drier but may be I imagined it. I'll check again.

Haven't taken a reading of the wet tank yet. Will do soonest possible.



Quote:
Originally Posted by Booyah45828 View Post

As far as air pressure and throttle issues, as said by others, the throttle is electronic and is completely seperate from the air system. I doubt the two problems are related.
Quote:
Originally Posted by Mountain Gnome View Post
What year is your bus? My 1999 TC1000 5.9L 24V will respond to the accelerator pedal with no air in the system (after bleeding the tanks down completely).
It's a 2002.
Are you missing an "AIR THROTTLE & SUSPENSION" petcock/valve on the manifold by the front air tanks like this one?
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Old 10-18-2018, 08:02 AM   #16
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Quote:
Originally Posted by Tomas View Post

Let me see if I understand how its plumbed correctly. From the compressor to the governor to the wet tank. From the wet tank to the drier and from the drier to the front and rear "dry" tanks. Is that correct? I thought I saw a hose going directly from the governor to the drier but may be I imagined it. I'll check again.

Haven't taken a reading of the wet tank yet. Will do soonest possible.
No, the compressor build the air pressure, then sends it to the drier(driers are optional, most have them, a few don't). It then travels to the wet tank, which will either have the governor attached to it, or it will send a small reference line to the governor wherever it is mounted. Sometimes it's mounted on a frame rail, sometimes it's mounted on the compressor. After the wet tank, air should travel through a check valve into the primary and secondary air tanks.

The governor is nothing more then a spring loaded shuttle valve. When air pressure(around 125 psi) overpowers the spring, the valve moves sending air pressure to the compressor and air drier, shutting the compressor off and purging the drier. When air pressure to the governor drops below 100 psi, the shuttle valve closes, releasing the psi sent to the compressor and drier, allowing both of those items to work again.
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Old 10-18-2018, 10:48 AM   #17
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Quote:
Originally Posted by Tomas View Post
It's a 2002.
Are you missing an "AIR THROTTLE & SUSPENSION" petcock/valve on the manifold by the front air tanks like this one?
I do not have that valve. So you have air suspension!?!?! Lucky....or is that for another air-powered accessory? My air-ride-driver's-seat doesn't work. I wonder which system it takes air from?

Note one valve has been replaced. I need to replace another, but it won't budge to unscrew it. It is my slow leak, especially when cold outside...
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Old 10-19-2018, 06:10 AM   #18
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Yes. Leaf springs in the front and air bags in the back.
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Old 10-19-2018, 06:22 AM   #19
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Yes. Leaf springs in the front and air bags in the back.
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Old 10-19-2018, 07:58 AM   #20
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It struck me yesterday that maybe you have a blown fuse. There is a hidden fuse panel on the front-side of the dash-display, behind a screw-on cover with 4 screws on my bus. But none seem related to your issue.
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