# priming a C7 accert after fuel filter change



## ponyboy123

I am about to put a new set of fuel filters on my 2006 M2 frieghtliner. I can't find a hand primer any where on the fuel system. My question, how do you prime this CAT C& accert if there is no hand primer?


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## NICHOLS LANDSCA

Mine doesn't have a primer either, I just fill the filters with injector cleaner or diesel. I'm really anal so I fill them through the outside holes not down the center so it actually gets filtered


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## Sabsan84

i believe you just turn the key and the fuel pump will prime itself, however, there may be a primer switch in the dash board, like on the volvos. But you shouldnt need to prime it if it didnt run out of fuel and you fill the filter up good before you spin in back on


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## ponyboy123

Thanks dudes, I will get back to ya on this. My first time changing fuel filters so this is all handy info.


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## leolkfrm

some filter housings have a bleed screw to let air out....freightliner is known for being differant when putting things together


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## JohnnyU

Pre-filling filters is strongly discouraged as it allows unfiltered fuel past the filters (regardless of if you fill from the outside, it's still not recommended). 

Some engines have an electric fuel priming pump, others have a port where you can bolt on the old hand priming pumps.


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## ponyboy123

Never really thought about prefilling filters to be bad, but will the fuel system prime if it has to expel that much air out of the filter? It makes sense not to prefill filters but is it a necesity?


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## SIWEL

every diesels class i have taken has said to prefill the filters with fuel. You want to start the engine at about half throttle, that way if there is any air in teh system it can pass thru and wont lose the system. if you have an eletric fuel pump, turn the key on and wait 30 seconds or so and shut it off and repeat a few times.


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## JohnnyU

Creek View Prop;1376375 said:


> every diesels class i have taken has said to prefill the filters with fuel. You want to start the engine at about half throttle, that way if there is any air in teh system it can pass thru and wont lose the system. if you have an eletric fuel pump, turn the key on and wait 30 seconds or so and shut it off and repeat a few times.


Were those classes centered around the new high pressure common rail injection systems? The practice of prefilling fuel filters is now strongly discouraged. I fight this batter (debris-caused failures) on a nearly daily basis.


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## SNOWLORD

Every fuel filter we change here gets filled with diesel before being put on our bulk fuel tanks have filters on them, have never had a problem in all the years.


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## SullivanSeptic

Just spin on the new filter. Then open the bleed screw and turn the key to on. It will run the fuel pump and fill the filter. Then start. No need to prefill them


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