SEMack Posted May 3, 2018 Share Posted May 3, 2018 We recently bought a 2012 CHU613 with MP8. Started fine the first six months and now we have to pump the accelerator to make it start. Any thoughts? Thanks Quote Link to comment https://www.bigmacktrucks.com/topic/53281-def-mp8-hard-to-start/ Share on other sites More sharing options...
turckster Posted May 4, 2018 Share Posted May 4, 2018 Check for fuel wicking around the plastic cap before the fuel primer pump. If you use the primer pump and fuel leaks around the cap you need to replace the cap--Mack has a replacement kit for it. If it is ok, remove the fuel tank caps, using a flash light check for air bubbling out the fuel return pipe in either or both tanks. If you are getting a consistent amount of air bubbles coming out the return fuel tube it is either leaking injector cup(s) or a faulty 7th inejctor "T"fitting check valve. Remove the air line to the 7th inj. "T" fitting, if it was faulty the air bubbles will eventually disappear. If the bubbles remain then most likely you have a leaking injector cup(s). Quote Link to comment https://www.bigmacktrucks.com/topic/53281-def-mp8-hard-to-start/#findComment-398208 Share on other sites More sharing options...
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