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I have 2000 Gmc with cat engine 3126. We have problem with…

Hi i have 2000...

Hi i have 2000 Gmc with cat engine 3126.
We have problem with starting the truck. Sometime it wont start just cranking and cranking, and we use engine start spray. What could be the problem?

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

2000 gmc c6500

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

We've check fuel line it fine. This engine does not have a manual fuel pump

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Answered in 6 minutes by:
9/28/2016
Technician: Cat Man, Cat Engine Expert replied 6 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.
Verified
Thanks for asking your question. I will try and help you out.
There are several things that can cause a hard start like this.
Let me ask you a few questions.
When it does start off either, does it run great right off the bat? Or does it run a little rough?
Also, do you know if there are any codes in the engine ECM?
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Customer reply replied 6 years ago
When it won't start there is no light or codes on small code screen on drivers left leg side. Once it started there is no issue it smokes little bit once when started and after that no problem.
Today I tried to keep cranking and it started third time after cranking 3-4 seconds.
Technician: Cat Man, Cat Engine Expert replied 6 years ago
Thanks for the information.
There are two things I have seen cause this.
The first is the fuel is leaking down from the head. I see this a lot. Two things hold fuel in the head. The fuel pressure regulator on the back of the head. As the fuel pump on the back of the heui pump. Most often I find the regulator causing the leak down.
Second is a faulty engine speed timing sensor. Your engine has two. They come as a pair and are on the drivers side of the engine on the back of the front cover. Under the heui and behind the air compressor. The lower one is the primary start sensor. It can fail and cause hard starting.
If replacing the regulator does not help. I would next suspect the engine speed timing sensor.
Please reply back if you need more help or have more questions. I am happy to assist.
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Technician: Cat Man, Cat Engine Expert replied 6 years ago

Hey, I just wanted to see how things were going. Please reply back 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 6 years ago
Timing sensor was loose and leak.
Thank you for your help.
Technician: Cat Man, Cat Engine Expert replied 6 years ago
You are very welcome my friend. I am happy I could help.
Cat Man
Cat Man, Cat Engine Expert
Category: Medium and Heavy Trucks
Satisfied Customers: 10,344
Experience: I am ASE Master Truck Certified.
Verified
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