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Cat Man
Cat Man, Cat Engine Expert
Category: Medium and Heavy Trucks
Satisfied Customers: 8813
Experience:  I am ASE Master Truck Certified.
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My 07 c15 will crank but won't start, 07 freightliner

Customer Question

My 07 c15 will crank but won't start
JA: What is the complete model and serial number of your machine?
Customer: 07 freightliner classic 1fujf6avx7dx67365
JA: Are you fixing this yourself? What have you tried so far?
Customer: I shut it off 3 hrs ago I have power to the ecm there is a solenoid top left corner of the engine with the key on I just keep clicking plus the check engine light doesn't come on when I turn on the key
JA: Anything else you want the equipment mechanic to know before I connect you?
Customer: No hopefully this will be enough for them
Submitted: 9 months ago.
Category: Medium and Heavy Trucks
Customer: replied 9 months ago.
Sorry solenoid on the right
Expert:  Cat Man replied 9 months ago.
Thanks for asking your question. I will try and help you out.
So the yellow check engine light does not come on when the key is turned to the on position?
Expert:  Cat Man replied 9 months ago.
If the yellow check engine light comes on, this indicates the engine ECM is receiving power and functioning. There are several things that can cause a crank no start on this engine.
The first is a low or no fuel pressure condition. The engine needs at least 35 psi to start. If it is low, the injectors will not get filled and it will not start. If the engine has a hand priming pump, and it gets stiff when operating it, the engine has enough pressure to start. If there is no hand priming pump, I would connect a psi gauge and measure the pressure. If the pressure is low, I would change the fuel filters first if you haven’t already. If it is still low, I would suspect a failed fuel pressure regulator in the secondary fuel filter housing, a weak fuel transfer pump, or restricted fuel inlet line. The pump is located on the front of the engine.
Second is a failed engine speed timing sensor. Some engine have one, some have two. It depends on your engine serial number. If the engine speed timing sensor has failed, the ECM gets an RPM/TDC signal and will not send AC to the injectors.
Next is low battery voltage to the ECM while cranking. The ECM must have at least 7.5 volts DC to operate. I have seen weak batteries or a poor connection cause low voltage. You could have a poor connection at the batteries or starter.
Next is a faulty engine ECM. The ECM has an injector driver module inside. This is what powers the injectors. If it fails, the ECM will log injector codes for all the injectors.
Lastly are worn injectors. Over time the injectors can wear if they have a lot of hours on them. To verify, I like to check AC to the injectors while cranking. You should have between 20-40 AC while cranking. If you do, and you have good fuel pressure, the injectors are worn. If you do not have 20-40 AC while cranking, you have either a failed engine speed timing signal, low power to the ECM while cranking, ot a failed ECM.
Most often when these things are happening there will be diagnostic codes in the ECM. If your engine has cruise control switches, you can pull the codes. If you have never done this, let me know. I can get you the procedure.
Please reply back if you need more help or have more questions. I am happy to assist.
Expert:  Cat Man replied 9 months ago.
Hey. I just wanted to see how things were going. Please let me know if you need more help. I am happy to assist. If my information was helpful, please leave a good or higher rating so that I receive credit. Thanks.

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