**PLEASE HELP** 69 PD4107 Starts and Idles fine but have NO THROTTLE RESPONSE

[69M4107]

Need your help again guys, my 69 model 4107 Starts instantly, Idles great and airs up like it should but I have no Throttle Response in my air throttle. I checked and the air throttle is working as it should but noting happens when I hit the pedal! Has anyone ever dealt with this problem?

[luvrbus]

If the fast idle is activated you get no throttle response make sure it is off 

[richard5933]

The air throttle works off the auxiliary tank and requires a set PSI level before it will function. Does anything else on the aux tank work?

Are you sure that your auxiliary tank is getting air? It's possible to have pressure show on the gauge but not have pressure in all your tanks. There is (I believe) pressure switch that only allows the auxiliary tank to fill after the main system reaches a pre-set pressure.

Check your manual and chase it backwards. Make sure you have air in the tank feeding the pedal. If not, keep going back till you find the problem. Likely something small but annoying. I'm guessing a stuck pressure switch or regulator.

If there is proper pressure in the aux tank, make sure there are no obstructions in the line feeding the pedal or in the pedal itself. Luckily, most of this stuff is designed to be opened, cleaned/serviced, and put back together.

[richard5933]

Just re-read your other thread...

Is the problem that the air throttle is not moving the rack or that the rack is not doing anything?

Perhaps your injectors/rack is/are stuck?

If so, lucky to be stuck at idle rather than wide open and causing a runaway.

More information needed for us to help you, I think.

[69M4107]

The air throttle works off the auxiliary tank and requires a set PSI level before it will function. Does anything else on the aux tank work?

Are you sure that your auxiliary tank is getting air? It's possible to have pressure show on the gauge but not have pressure in all your tanks. There is (I believe) pressure switch that only allows the auxiliary tank to fill after the main system reaches a pre-set pressure.

Check your manual and chase it backwards. Make sure you have air in the tank feeding the pedal. If not, keep going back till you find the problem. Likely something small but annoying. I'm guessing a stuck pressure switch or regulator.

If there is proper pressure in the aux tank, make sure there are no obstructions in the line feeding the pedal or in the pedal itself. Luckily, most of this stuff is designed to be opened, cleaned/serviced, and put back together.

So my air system is working properly. It airs up quickly and holds. When I press the throttle it moves the throttle lever. I took the governor cover off and everything is free and working as it should. I also removed the valve cover and checked the rack and it too is free. It’s almost like there’s something stopping the injectors from spraying. Are there any failsafes That shut off the fuel pump? And would the motor even Idle if the fuel pump was not working?

[69M4107]

If the fast idle is activated you get no throttle response make sure it is off

My Fast Idle has never worked, the wires are cut and the air line isn’t connected to anything and it has run just fine.

[luvrbus]

 You pulled 1 valve cover are both ?,the governor from idle to full throttle only moves less than a 1/2 inch if the engine idles the injectors are fueling,you check each injector rack on the spring loaded  fuel control tubes not the control tube and make sure the shutdown cylinder is fully retracted ,they hang sometimes and will not allow throttle 

[69M4107]

You pulled 1 valve cover are both ?,the governor from idle to full throttle only moves less than a 1/2 inch if the engine idles the injectors are fueling,you check each injector rack on the spring loaded  fuel control tubes not the control tube and make sure the shutdown cylinder is fully retracted ,they hang sometimes and will not allow throttle

So I noticed that the emergency stop mech on the side of my blower was in the stop position, when I slid the cam lock up and put it into the run position it did just that, started to run away on me. I am at a loss and have no Idea where to even look next.

[luvrbus]

Pull the top back off the governor you missed the slot with the pin 

[69M4107]

Pull the top back off the governor you missed the slot with the pin

What do you mean? The throttle pin is in the fork and the shut down bar sits under the pin to push up and kill the engine. What else is there that I could have missed?

[luvrbus]

You stated you removed the top off the governor,if you did the lever control pin is easy to miss the fork inside 

[69M4107]

So I double check to make sure that I did not miss the fork, I checked both racks and all 8 injectors free and bouncing back. What I don’t understand is number one I have really dark black smoke while idling, and it idles while the emergency stop is in the off position. When I move the cam lock to the run Position it starts running away. I thought with it in the stop position it wouldn’t be able to start?

[buswarrior]

Emergency stop is there to prevent a run-away. Some buses will stall, some will chug, some will idle.

Seen it all, 1600 2 stroke transit buses back in the day.

You've got something totally screwed up and backwards in your fuel controls.

Time to get the manual out and go through it all, piece by piece.

Happy coaching!
Buswarrior

[luvrbus]

Did you fool with the fast idle like taking it out and reinstalling the cylinder, if the buffer is screwed in to far it will make you need a under wear change when it fires up

[richard5933]

Photos??