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Cat Man
Cat Man, Cat Engine Expert
Category: Medium and Heavy Trucks
Satisfied Customers: 8421
Experience:  I am ASE Master Truck Certified.
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I have a 2004 peterbilt with a C7 cat esn:KAL23191 the

Customer Question

i have a 2004 peterbilt with a C7 cat esn:KAL23191
the initial problem with this truck was it dying checked codes had active code for actuation pressure replaced actuation pressure sensor ran but started smoking bad and had miss on #2 injector replaced injector ran fine but still smoked after a day of use truck died and would no longer start again had code for actuation pressure replaced heui pump truck still smoking replaced weak injector #3 still smoking and now sputtering about 15 to 20 mins running had peterbilt field tech check recommended injector orings did that problem persisted removed exhaust manifold #1 smoking excessive replaced remaining injectors no more smoke but still acts up with the sputter after running about 20 mins
stumped any ideas
Submitted: 3 months ago.
Category: Medium and Heavy Trucks
Expert:  Cat Man replied 3 months ago.
Thanks for asking your question. I will try and help you out.
When the engine is running , does the yellow check engine light come on? Or does it sputter with no light?
Customer: replied 3 months ago.
No check engine light comes on
Expert:  Cat Man replied 3 months ago.
Thanks for the information.Since the yellow engine light does not come on. I would suspect a fuel pressure issue.If there is a low fuel pressure problem, the check engine light will not come on and the engine will have low power. Your engine should maintain a fuel pressure between 65 and 85 psi. There is a plug beside of the secondary fuel filter that is used to check the pressure. If it is low, I would first try the fuel filters if you haven’t already. If it is still low, you may have a failed fuel pressure regulator, which is located on the back of the cylinder head. I have replaced a ton of these for low fuel pressure. It is kinda a known problem. You could also have a weak fuel transfer pump or restricted hand primer pump, if your engine has one.Please reply back if you need more help or have more questions. I am happy to assist.
Customer: replied 3 months ago.

i replaced fuel filters already then fuel pressure regulator and hand pump but still acts the same the issue acts almost like an injector cutting out just acts up for a few seconds the goes back to a good idle no engine light comes

Expert:  Cat Man replied 3 months ago.
Thanks for the information.
Have you connected a psi gauge to check the fuel pressure?
Expert:  Cat Man replied 3 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.
Customer: replied 3 months ago.

no i have not couldnt find the fuel port you mentioned

Expert:  Cat Man replied 3 months ago.
There should be a quick disconnect or plug at the secondary filter on the engine. Let me know if you need more help.
Customer: replied 3 months ago.

is it the plug by the hand priming pump the only other filter i have is on the frame rail

Expert:  Cat Man replied 3 months ago.
Near the hand priming pump
Customer: replied 3 months ago.

fuel stayed at 75 psi and still acting up no change in pressure

Expert:  Cat Man replied 3 months ago.
Thanks for the information.
I would suspect you have worn injectors. I have seen this before. If the fuel pressure is fine, and no check engine light on, the injectors are most likely causing this. Over time they can become worn and cause low power. Also, the Heui pump can also fail and begins putting very small metal debris in the oil and it will damage the injectors. To verify,just remove the oil dipstick and rub some on your finger. If you see shiney metal particles. The pump has failed and damaged the injectors.Please let me know if you need more help or have more questions.
Customer: replied 3 months ago.

initially engine would not run so changed heui pump and also all injectors due to debris in metal

Expert:  Cat Man replied 3 months ago.
You may want to check for a return line restriction. Especially in the regulator on the back of the head.
This can cause hot fuel and the engine to run rough. I've seen this many times.
Customer: replied 3 months ago.

regulator has been replaced and line was blown thru with shop air

Expert:  Cat Man replied 3 months ago.
You may have something wrong with the fuel. Water or contaminated fuel.

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