Medium and Heavy Trucks
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Hi Tammy. My name is***** will be glad to help. What is the make , model and serial of the engine?
For initial checks, check the fuel lines between the tank and pump for leaks or restrictions indicating a loss of fuel supply pressure and sucking in air. Install a sight glass or clear hose to check for bubbles indicating air in the system. Let me know what engine make and model so I can give you details on the engine checks whether it is Cat C15, Cummins ISX, Detroit...??? Let me know
Hi, It appears there is some technical difficulty. Let me know if you can see my responses
I can provide with some schematics and troubleshooting info to help once I get your engine information.
What are the first three characters of the engine serial number?
Is the check engine light coming on at all?
Click here for your schematics.
Check your fuel pressure with a gauge. Should be 75-90 PSI consistent even under a load. If low your could have a faulty pressure regulator or transfer pump. The other cause is faulty injectors if high mileage. You can have an injector test done with Cat ET connected. Let me know
That is in range for boost. Are you getting any fault codes? Check engine light come on? Hard starting? you mention when the air compressor is pumping/cut in the symptoms are worse? Or are the symptoms only present when the air compressor is cut in? What is the complete engine model and serial number from the ID tag?
If the fuel system checks out ok and there is no codes then check your throttle position sensor for loss of signal and corrosion/poor connections in the harness, Check the ECM power connections between the battery box and ECM for corrosion or loose connections, Check the cam sensor and harness for loss of signal or erratic signal and it would be worth while to read live data with Cat ET connected to monitor what is happening with the sensors etc when this problem occurs. Also reflashing and updating the ECM software for test purposes might not be a bad idea or if you have access to a test ECM. Be sure to check all grounds which could cause a lot of odd things to happen. Let me know
Cat ET is the diagnostic software for Caterpillar programmed into a laptop that plugs into the diagnostic connector using a communication adapter between the truck and laptop. If you know a shop that has this or a scan tool that will read live data. The Cat ET setup is pricey. You can go on Ebay and buy a Launch brand reader and if you have time to wait buy it from a China seller to get it at half the money. I got one on my road truck and it works great.
Thanks for the update. Check the engine brake circuit as well. It sounds like you might have the engine brake coming on or sticking when it should not be. Watch to see if this happens with the engine brake turned off.
Thanks for the update. I think you have multiple things going on. For the engine, if the fuel system tests good and the injectors test good after being tested with Cat ET software plugged in and they pass then I recommend having the valves, injectors, and jakes adjusted and the jake housings inspected for leaks and possible sticking plungers, etc. With the valve covers off and engine idling you can test the jakes by pressing the center of the solenoid one at a time to see if they are sticking or working properly. As far as your vibration, Check your suspension and steering components, driveline components and input and output yokes for looseness, center bearing, engine and transmission mounts.