How JustAnswer Works:
  • Ask an Expert
    Experts are full of valuable knowledge and are ready to help with any question. Credentials confirmed by a Fortune 500 verification firm.
  • Get a Professional Answer
    Via email, text message, or notification as you wait on our site.
    Ask follow up questions if you need to.
  • 100% Satisfaction Guarantee
    Rate the answer you receive.
Ask Cat Man Your Own Question
Cat Man
Cat Man, Cat Engine Expert
Category: Medium and Heavy Trucks
Satisfied Customers: 8344
Experience:  I am ASE Master Truck Certified.
Type Your Medium and Heavy Trucks Question Here...
Cat Man is online now
A new question is answered every 9 seconds

I have c 12 westernstar 2000 won t fire up shot of ether

Customer Question

i have c 12 westernstar 2000 won t fire up shot of ether fires up then stops when runs out fuel filters are full
JA: What's the make/model/year of your truck? Engine type?
Customer: c 12 westernstar cat engine year 2000
JA: Are you fixing your truck yourself? What have you tried so far?
Customer: primed the lines filters blew air in line to tank the other day ai started then backed up to fifth wheel hitch slamed kinda like jerk on to hitch it stalled went dead now won t start again
JA: Anything else you want the truck mechanic to know before I connect you?
Customer: looks like might have weak pump took line off and cranked it not much pressure coming thru and lines all checked and blown out
Submitted: 2 months ago.
Category: Medium and Heavy Trucks
Expert:  Cat Man replied 2 months ago.
Thanks for asking your question. I will try and help you out.
Does the yellow check engine light come on when you turn the key to the on position?
Customer: replied 2 months ago.
Expert:  Cat Man replied 2 months ago.
Thanks for the information.If the yellow check engine light does not come on when the key is turned to the on position and the engine will not start, there are only 2 things that can cause this.The first and most common is the engine ECM is not getting the correct power and ground to function. The ECM should have power on pins 52, 53, and 70 of the rear most ECM connector. This is the truck side harness connector. 70 is the key switch wire. The grounds are on pins 65 and 67. You can remove the connector and check for power on these pins. If you do not have power on these pins, you most likely have a blown fuse in the electrical system. I would check all fuses first.If you do have correct power and ground to the ECM, you most likely have a failed ECM. I have seen this many times over the years. To confirm the ECM is bad, you would need to install a known good ECM on the engine or you can take the ECM to the dealer to be tested. Unfortunately the ECM cannot be repaired. Replacement is the only option. I am sorry. I wish I had better news.Please reply back if you need more help or have more questions. I am happy to assist.
Customer: replied 2 months ago.
checked all fuses only light comes on data error what and where is ECM
Expert:  Cat Man replied 2 months ago.
The ECM is the engine computer on the drivers side of the engine. It has two harnesses connected to it. One is the truck harness. The other is the engine harness
Customer: replied 2 months ago.
would low battrie voltage cause problem also
Expert:  Cat Man replied 2 months ago.
it can. If the voltage drops below 7.5 volts. The ECM can not function.
Customer: replied 2 months ago.
ok we found a bad ground wire to battrie but it still turned over pretty good prior to finding loose ground wire
Expert:  Cat Man replied 2 months ago.
I would check power to the ECM. If you have power to the ECM and no check engine light. I would suspect the ECM is faulty.
Customer: replied 2 months ago.
check engine lite is on when turn on key
Expert:  Cat Man replied 2 months ago.
Thanks for the information.Since 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 2 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.

Related Medium and Heavy Trucks Questions