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Cat Man
Cat Man, Cat Engine Expert
Category: Construction and Road Equipment
Satisfied Customers: 8764
Experience:  I am ASE Master Certified.
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2005 c-15 mx motor inframed 50,000 miles ago with new evvas,

Customer Question

2005 c-15 mx motor inframed 50,000 miles ago with new evvas, new twin turbos update bracket,new cylinder head, liners pistons ,ect this motor seems to disconnect from the throttle and studder than slowly pick up. this happens @55mph also if you let it go to idle when it happens and stop the truck the idle surges up and down then stabilizes any ideas
Submitted: 2 years ago.
Category: Construction and Road Equipment
Expert:  Cat Man replied 2 years ago.
Hi. Thanks for asking your question! I will try and help you out.
Does the yellow check engine light come on when this happens?
Customer: replied 2 years ago.
no engine lights red or yellow
Customer: replied 2 years ago.
ps the truck also has a new feul pedal and new t.p.s.
Expert:  Cat Man replied 2 years ago.
Thanks for the information.
Since there is no light. I would first suspect a low fuel pressure problem. I have seen this many times.
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 75 and 90 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 underneath the bottom of the filter housing. 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.

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