C-9 occasionally quits running at idle or low RPM

[Albert Balika]

Steve and Fred, As always, your input is invaluable to mechanically challenged folks like me. I actually went to the electrical diagrams mentioned about a year ago based on your suggestions, made copies of all charts therein, laminated them and keep them in the compartment under driver seat. That's the good news. The bad news is I don't know what each of them are for. I will do as you suggest Fred, and replace all of the relays you identified. I actually bought several of these relays last year. It has been suggested that my problem may be related to the "injection accusation pressure sensor" failure. So now, I am looking at the following possibilities, 1) changing the primary and secondary fuel filters, 2) replacing the related relays, 3) possible draining and cleaning fuel tank, 4) possibility of replacing the "low pressure fuel pump", 4) replacing the "injection accusation pressure sensor. Again, all comments and suggestions are welcome. Thanks, Albert

[Eric Maclean Co-Admin]

Albert
The pressure actuation solenoid controls the huei oil pressure on to the injectors the ending ECM  dictates the injection pressure and uses a sensor to read the oil pressure down stream of the pressure actuation solenoid .if for some reason the ECM doesn't see the pressure it has requested from the pressure actuation sensor it will set a fault code .

You may be looking at two different problems
Because as you stated the engine was hard to restart as if it was starved for fuel I would start by 

1) run a scan tool on the engine ECM ( preferably Cat ET software ) looking for fault codes and or any history of derate event or forced shut down) at this time a injection actuation pressure test can be run to verify function.
With cat ET you can also read the ignition source voltage to the ECM to see if that is your problem.

2)changing both the water separator and the fuel filters ( dump the water separator contents into a jar and inspect for water and dirt the cut the filter can open and spread out the filter element to see how dirty it is)

3) run a fuel rail pressure test to see if the primary fuel pump can meet specified rail pressure and that the fuel pressure regulator hasn't gone bad.

4) check for air in the fuel at the fuel rail return ( air can be introduced into the system on the suction side of the primary fuel pump by a back connection or bad suction side fuel line

If your Aladin system is warning you of an imminent ignition system shutting down the only place I can think that it can get that information from is the engine ECM  .
The ECM may do this for several reasons  over heating , low oil pressure , low coolant level are just a few
BTW coolant level sensors are usually add by the coach builder and not the engine manufacturer and are a common fail item.
The hard stat and inability to pick up rpm would most likely be fuel related issues ( air in the fuel or plugged fuel filter)

Sorry to go on so long
Hope this helps
Eric

[Albert Balika]

Fred and Steve, As always, thanks for your help. I am going to change all of those relays. I am also going to change the primary and secondary fuel filters. I understand that the "injection accusation pressure sensor" may be the culprit. Again, our club should be eternally grateful to you folks and others for helping us mechanically challenged owners navigate these problems. I can't imagine what owning one of these rigs would be like without your more than generous help. Any suggestions and comments would be welcomed. Regards, Albert

[Fred Brooks]

   Did you check out "Ask Dave" under technical? Look towards the end under intermittent shut down. Fred

[Roy Boles]

The symptoms you described sound exactly like what I experienced on my 1996 Monterey. When that solenoid fails it kills the power to the ignition side of the power buss. Find and replace that solenoid. That should cure your problem. 

[Joel Ashley]

Problem is, Roy, he apparently doesn’t have the solenoid that most of us do.  Ignition reliant devices are supplied by relays.