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I have a 1998 Freightliner FL70 with a cat 3126, cel on, no…

Customer Question
I have a 1998...

I have a 1998 Freightliner FL70 with a cat 3126, cel on, no power, stalled out. Did restart and dron

Mechanic's Assistant: What is the complete model and serial number of your machine?

1998 Freightliner FL 70, Cat 3126. Codes are 15 17 39 and 71

Mechanic's Assistant: Are you fixing this yourself? What have you tried so far?

Yes

Mechanic's Assistant: Anything else you want the equipment mechanic to know before I connect you?

Last month it did not start found oil pressure sensor bad. Replaced it and started. No problems until now

Submitted: 8 months ago.Category: Medium and Heavy Trucks
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10/2/2017
Technician: Cat Man, Cat Engine Expert replied 8 months ago
Cat Man
Cat Man, Cat Engine Expert
Category: Medium and Heavy Trucks
Satisfied Customers: 9,363
Experience: I am ASE Master Truck Certified.
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Thanks for asking your question. I will try and help you out.Codea 39 is defined as an Injection Actuation Pressure System fault. Code 15 is defined as injection actuation pressure erratic. I see this a lot on these engines. These code indicates the ECM is not seeing the correct Injection Actuation Pressure. These codes and problem is caused by several things.The first and most common is a faulty Injection Actuation Pressure Control Valve. Also known as an IAPCV. It has two wires connected to it and is screwed into the High pressure HEUI pump.
Second is a Faulty HEUI pump. To test a high pressure 5000 psi gauge is needed to connect to the outlet of the HEUI pump.
Third is a faulty IAP sensor
And lastly is a leaking injector.Code 17 is defined as excessive actuation pressure. This can only be caused by a bad iapcv or Heui pump.Code 71 is a low power to ecm code. I would not worry about this one. It's on most of these engines when I see them.Please reply back if you need more help or have more questions. I am happy to assist.
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Customer reply replied 8 months ago
I replaced the GP-Solenoid a month ago. The nut on the back side fell off. I replaced sensor and it started and ran for a month.I did not clear codes. The other day when the cel came on it lost power, made it back to shop. Now it won't start.
Technician: Cat Man, Cat Engine Expert replied 8 months ago
Thanks for the information.
So the engine is a cracked and no start ? And the yellow check engine light comes on when the key is turned to the on position?
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Technician: Cat Man, Cat Engine Expert replied 8 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 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 8 months ago
I gave you all the codes 15, 17, 39, 71.
Technician: Cat Man, Cat Engine Expert replied 8 months ago
I know. Thanks for the information. I suspect you have a faulty iapcv or Heui pump. I see this a lot.
Please reply back if you need more help or have more questions. I am happy to assist.
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Customer reply replied 8 months ago
How would I test these 2 components
Technician: Cat Man, Cat Engine Expert replied 8 months ago
To test you must connect a 5000 psi gauge to the outlet of the Heui pump. While cranking. The Heui must make a minimum of 4000 psi steady. If it does not. You change the iapcv and retest. If it still below 4000. The Heui pump is bad.
Please reply back if you need more help or have more questions. I am happy to assist.
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Customer reply replied 8 months ago
Like I said before I replaced the iapcv a month ago. Part #(###) ###-#### It started and ran fine after I replaced it,
Technician: Cat Man, Cat Engine Expert replied 8 months ago
I see. You may have a bad Heui then. I have seen new iapcv go bad soon after replacing but not often.
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Customer reply replied 8 months ago
Kind of a expensive procedure if iapcv is not bad. Is there a way to test the iapcv out of pump.
Technician: Cat Man, Cat Engine Expert replied 8 months ago
Unfortunately not. Sorry. I wish there was a way.
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Customer reply replied 8 months ago
This test gauge, is it the same for testing hydraulic pump pressure.
Technician: Cat Man, Cat Engine Expert replied 8 months ago
it is.
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Technician: Cat Man, Cat Engine Expert replied 8 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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Customer reply replied 8 months ago
Waiting for my test gauges to arrive.
Technician: Cat Man, Cat Engine Expert replied 8 months ago
10-4
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