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Daniel Wilson
Daniel Wilson,
Category: Car
Satisfied Customers: 5185
Experience:  Owner at DJ Wilson
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2001 freightline mt 45, stalls when hot, (idle one hour)

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2001 freightline mt 45, stalls when hot, (idle one hour) crank no start

Good morning, have you replaced the camshaft position sensor?

Customer: replied 1 year ago.
crankshaft sensor. losing power to ignition relay when dies. ran new wire and no throttle response. wire is fed from ecm.

It could be a short in one of the sensors. I do not have any of the books to help walk you through testing so I am going to opt out and hope one of the heavy duty techs have access to the diagrams.

Hi McCoy, My name is***** see you have installed a used ECM. Was the ECM reflashed with the most current software updates or is it still the original programming?

What is the complete model and engine serial number from the ID tag?

Customer: replied 1 year ago.
No, it was from the guy's scrap yard. used one works. basically nothing has solved this stall and no start issue.
Customer: replied 1 year ago.
4UZAANBW81CH52706 - vin,
56724508 - engine serial
Customer: replied 1 year ago.
2001 Freightliner MT45

Thanks for the update. Do you have the model as it is listed on the ID tag?

complete engine model I mean

Customer: replied 1 year ago.
That I do not have. Could not find tag, so dealer gave me the engine serial

What injection pump is on this truck? Is it a CAPS pump?

Customer: replied 1 year ago.
VP44029x is the part number we put on.

Thanks for the information. First check and verify there is no restrictions or leaks between the fuel tank and pump that would caus the system to suck in air. Also check the fuel transfer/lift pump is supplying the VP44 pump and you have good fuel supply to the pump. Install a clear hose to watch for air bubbles on the suction side and the return side of the system. Excessive air bubbles on the suction indicate one of the problems I listed. You can also try running the suction and return into a separate reservoir to see if the problem exists. Let me know what fault codes you have logged in the ECM

Click on this link for a great publication for extra FYI on this style pump and system to assist in troubleshooting. I will get you a diagram as well.


Customer: replied 1 year ago.
no faulty codes. they wont come up on dash when you push the fault button. so you think after running an hour, it's sucking air?
Customer: replied 1 year ago.
she stalls after an hour when she gets to temp, and wont restart until it cools off, if that helps

As part of troubleshooting installing the clear hose will tell us if there are bubbles there is a supply problem. If that checks out okay then your problem is electrical if it shuts off instantly like turning off the key. Click this link and see page two on how the VP44 relay ties into the system. Have you swapped relays? Check the relay and the powers and grounds. Here are the diagrams to help. Inspect the wiring and VP44 relay. Let me know.


what fault codes is it throwing?

Customer: replied 1 year ago.
relays have been swapped, no change. we lose feed from ecm to relay when it dies. 12 volts comes back when it starts

What fault codes are logged in the ECM when plugged in with a scan tool?

Eiter the ECM is shutting down for low coolant or another reason but there would be a code thrown if it is a shutdown. If no then the ECM circuit board likely has a problem such as a bad solder joint etc and effected by temperature meaning the ECM is the problem.

Customer: replied 1 year ago.
i cant get it to flash a code. same thing happened with used ecm. shuts off when hot. my guy is working on the other steps

Make sure all your power and grounds for the ECM are good, clean, tight and there is no corrosion or damage in any of the connectors. Have him use the diagrams to identify which pins to test with his volt/OHM meter. also see if you can get a hold of a scan tool to see if the scan tool will read the ECM and pull the codes. I am heading out for the afternoon but I will see any replies on my next available login. Let me know

Daniel Wilson,
Category: Car
Satisfied Customers: 5185
Experience: Owner at DJ Wilson
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