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Cat c7 serial #71176 wont run will start with ipr unplugged…

cat c7 serial #71176 wont...
cat c7 serial #71176 wont run will start with ipr unplugged and a shot of either dies out when i plug in the ipr new heui pump
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Answered in 3 minutes by:
12/29/2016
Technician: Cat Man, Cat Engine Expert replied 5 years ago
Cat Man
Cat Man, Cat Engine Expert
Category: Medium and Heavy Trucks
Satisfied Customers: 10,344
Experience: I am ASE Master Truck Certified.
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Thanks for asking your question. I will try and help you out.
Sounds like you have an injection actuation pressure problem. Could be a leak at an injector, a faulty heui pump, or faulty iap sensor.
When you turn the key to the on position , does the yellow check engine light come on?
Do you know what codes are in the ecm? I'm sure if you have this problem there should be codes.
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Customer reply replied 5 years ago
no codes yes the eninge light comes on
Technician: Cat Man, Cat Engine Expert replied 5 years ago
Thanks for the information.
I would like to try and pull the faulty codes by using the cruise control switches. If you have never done this. Here is how.Use the following procedure to retrieve the flash codes from the check engine light:
Turn the ignition key switch to the On position/ Engine OFF.
Turn the cruise control ON/OFF switch to the OFF position.
Move the SET/RESUME switch to either position. Hold that position until the yellow lamp begins to flash.
The yellow lamp will flash in order to indicate a two digit flash code and the SET/RESUME switch may be released. The sequence of flashes represents the system diagnostic message. Count the first sequence of flashes in order to determine the first digit of the flash code. After a two second pause, the second sequence of flashes will identify the second digit of the flash code.
Any additional flash codes will follow after a pause. These codes will be displayed in the same manner. Flash Code 55 indicates that No Detected Faults have occurred since the ignition key switch has been turned to the ON position.Let me know what two digit code you get and I can tell you what the problem is.
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Customer reply replied 5 years ago
i have a labtop with cat software im not getting any codes
Technician: Cat Man, Cat Engine Expert replied 5 years 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 25 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 on the back of the head or a weak fuel transfer pump. The pump is located on the back of the HEUI pump.Second is a low injection actuation pressure. This is the high pressure oil system that activates the injectors. The engine needs at least 870 psi to start. If it is low, you have either a failed Injection actuation pressure control valve in the HEUI pump, a weak HEUI pump, a high pressure oil leak at an injector, or a faulty Injection actuation pressure sensor. To test the sensor, just unplug it. If the engine starts, the sensor is bad. It has 3 wires and is located on top of the engine near the front and screwed into the head.Third is a failed engine speed timing sensor. Your engine has two. They are located on the driver’s side of the engine on the back of the engines front cover under the HEUI pump. The bottom sensor is the primary start sensor. If it has failed, the engine will be hard to start. The top one is the primary run sensor. They come as a pair.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.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.
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Customer reply replied 5 years ago
installed a new huei pump with fuel pump and ipr
Technician: Cat Man, Cat Engine Expert replied 5 years ago
How much actuation pressure do you show on ET while cranking?
Have you checked AC power to the injectors while cranking?
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Customer reply replied 5 years ago
with ipr plugged in around 3000psi ipr unplugged 500
Technician: Cat Man, Cat Engine Expert replied 5 years ago
If you have 3000 psi while cranking. That's way too high. Sounds like the heui pump pressure is stuck high.
Was it doing this before replacing the heui pump?
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Customer reply replied 5 years ago
no it wasnt
Technician: Cat Man, Cat Engine Expert replied 5 years ago
Thanks for the information. I believe the new pump you have is bad. I am sorry. But is see this from time to time.
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Customer reply replied 5 years ago
ok ill have to see if i can get another one what should the pressure be while cranking
Technician: Cat Man, Cat Engine Expert replied 5 years ago
The pressure should be around 1500 psi.
Cat Man
Cat Man, Cat Engine Expert
Category: Medium and Heavy Trucks
Satisfied Customers: 10,344
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Customer reply replied 5 years ago
ok thanks
Technician: Cat Man, Cat Engine Expert replied 5 years ago
You are very welcome my friend. I am happy I could help.
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