2008 hino help injector pump puking

Sutton

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New here and the 2008 7.7 liter to my knowledge the (was told when purchased 3wks ago) the engine has been rebuilt. I have a an issue with the injector pump. I replaced the pump. 4days on the road it puking fuel again from the injector pump. I live in a small town. This problem has perplexed the diesel shop.
 

Hino123

Seasoned Expediter
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Had a coworker replace 3 fuel pumps on a 2009. It finally made it’s way into my bay. I found someone had swapped the fuel supply and return lines at the frame mounted Davco filter. I have also seen people swap fuel lines up at the back of the head when replacing a transmission. The truck will run, but eventually the pump seal blows and leaks fuel. Check all of your fuel lines for proper routing,and make sure the fuel tank vent is not plugged. Good luck.
 

greasytshirt

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New here and the 2008 7.7 liter to my knowledge the (was told when purchased 3wks ago) the engine has been rebuilt. I have a an issue with the injector pump. I replaced the pump. 4days on the road it puking fuel again from the injector pump. I live in a small town. This problem has perplexed the diesel shop.
Where exactly is the pump leaking?
 

Sutton

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They are said it was leaking from the high pressure line to the rack. Replaced the high pressure line. When they started the truck ots missing.
 

greasytshirt

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Misfiring?
Has the leak been fixed?
It was running normally before the leak and the repair?
I'm trying to understand the sequence of events.

Debris in the fuel system can cause a misfire. I've seen a few cases of a spring inside the pump break and the pieces go into the common rail. The flow dampers on the rail have a small hole for the fuel to pass through and the spring pieces block the hole, causing a misfire.
 

greasytshirt

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The common rail has six flow dampers on it. They go between the rail and injector lines. One may have debris in it. Have them figure out which cylinder is misfiring, then disassemble the flow damper for that cylinder(s) and look for debris. If they don't have software that can see cylinder correction, they can look at exhaust manifold temp for each cylinder and find it that way.
 
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Hino123

Seasoned Expediter
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Alternatively you can grab the fuel line with 2 fingers and feel for a “pulse” of fuel. If you feel one( or two) with no pulse I would start by inspecting that injectors flow damper.
 
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