BarryMckociner Posted 13 hours ago Share Posted 13 hours ago I’ve got a 2003 RB688S with electronic (EUP’s) E7 400 engine in my dumptruck that is low on power and has a miss around 1,200-1,400 rpm. Miss is slight first thing in the morning but gets worse once warmed up. Truck idles fine and runs down the road okay once you get above 1,400rpm but as soon as you hit a hill loaded it slows down quick. Boost lags as well until I get to 1,600rpm. I’m leaning towards fuel return restrictor or lift pump. What are the specs for fuel pressure? Any help is appreciated Quote Link to comment https://www.bigmacktrucks.com/topic/75702-2003-mack-e7-low-power/ Share on other sites More sharing options...
Joey Mack Posted 9 hours ago Share Posted 9 hours ago 60-80 psi. Definitely check that. 1 Quote Link to comment https://www.bigmacktrucks.com/topic/75702-2003-mack-e7-low-power/#findComment-578013 Share on other sites More sharing options...
fjh Posted 8 hours ago Share Posted 8 hours ago Yup check that ! Any other symptoms? Smoke ? Color of smoke at what rpm ect all help with diagnosis! Quote Link to comment https://www.bigmacktrucks.com/topic/75702-2003-mack-e7-low-power/#findComment-578015 Share on other sites More sharing options...
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