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My 2008 Mack is showing fuel restrictions and running

Customer Question
My 2008 Mack is...

My 2008 Mack is showing fuel restrictions and running poorly

Mechanic's Assistant: What's the make/model/year of your truck? Engine type?

2008 Mack with mp 8 motor

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

Took all lines loose and blow air through, cleaned filter housing , changed filters twice , seen improvements but still stumbling when getting under a load , also noticed that my primer pump want get hard when pumping

Submitted: 1 year ago.Category: Medium and Heavy Trucks
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Answered in 3 minutes by:
2/13/2021
Technician: Curtis B., Technician replied 1 year ago
Curtis B.
Curtis B., Technician
Category: Medium and Heavy Trucks
Satisfied Customers: 43,336
Experience: Technician turned service manager on multiple lines of trucks and engines, used in industry.
Verified

Welcome to JUST ANSWER heavy equipment. With years of experience, I look forward to doing my best to help.

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Customer reply replied 1 year ago
You get my problem
Technician: Curtis B., Technician replied 1 year ago

Did you blow back into the tank outlet line from the filter housing? If all that is good, make a test line and attach it to the primer pump or inlet housing, and run the line back into the tank filler opening for a test, if it still acts up, replace the primer. If it clears, you have a problem from the removed line, back to the tank. The tank line, up to the primer has to be vacuum tight.

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Customer reply replied 1 year ago
I only got half of that , my filter was so tight I had to get big pipe wrench to get off would think I had a good vacuum
Technician: Curtis B., Technician replied 1 year ago

Leak doesn't have to be at the filter, can be on the fuel line or connection or restricted in the tank.

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Customer reply replied 1 year ago
Ok we took the line off at filter housing blow back to tank to make sure no restrictions and all checked out good blow back through filter housing norestrictions changed filter run for a day and shut down that evening next day hard to crank when it did crank run rough gonna take filter off extremely tighthad to get pipe wrench
Technician: Curtis B., Technician replied 1 year ago

Run the fuel test line test.

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Customer reply replied 1 year ago
Ok get a line and go directly from filter housing to fuel tank right
Technician: Curtis B., Technician replied 1 year ago

Yes, from the primer housing.

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Customer reply replied 1 year ago
Ok
Technician: Curtis B., Technician replied 1 year ago

Let me know.

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Customer reply replied 1 year ago
Ok I'm gonna have to get some fittings it has the fuel line that has bolt through it
Technician: Curtis B., Technician replied 1 year ago

OK>

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Customer reply replied 1 year ago
Ok I done that no change
Technician: Curtis B., Technician replied 1 year ago

So the test line attached at primer housing did not help? Replace the primer.

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Customer reply replied 1 year ago
The whole primer housing I can't rebuild it
Technician: Curtis B., Technician replied 1 year ago

The pump portion, with the primer diaphragm needs to be replaced.

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Customer reply replied 1 year ago
Ok will be tomorrow when Mack opens
Technician: Curtis B., Technician replied 1 year ago

OK>

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Curtis B.
Curtis B.
Curtis B., Technician
Category: Medium and Heavy Trucks
Satisfied Customers: 43,336
43,336 Satisfied Customers
Experience: Technician turned service manager on multiple lines of trucks and engines, used in industry.

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