Chmack 400 Posted May 11, 2017 Share Posted May 11, 2017 I have a ch mack 93 with 400 hp bosch german injector pump style engine . it misses now and then under load . we have put an electric lift pump on main fuel line it makes it a little better but still plays up and bypassed lift plunger on pump but still does it .am guessing injector pump is buggered and can i put i higher rated hp pump from same model engine and not have to change anything ? I been told a 427 one will work Quote Link to comment https://www.bigmacktrucks.com/topic/49796-ch-mack-400-problems/ Share on other sites More sharing options...
mike69mackman Posted May 14, 2017 Share Posted May 14, 2017 Check your tps function Quote Link to comment https://www.bigmacktrucks.com/topic/49796-ch-mack-400-problems/#findComment-369775 Share on other sites More sharing options...
Mackpro Posted May 14, 2017 Share Posted May 14, 2017 I remember replacing lots of the copper pump washers on the early Robert Bosch pumps. The new replacement washer was steel. I still have the socket for it. The later pumps had no washers at all Quote Link to comment https://www.bigmacktrucks.com/topic/49796-ch-mack-400-problems/#findComment-369782 Share on other sites More sharing options...
Mackpro Posted May 14, 2017 Share Posted May 14, 2017 Quote Link to comment https://www.bigmacktrucks.com/topic/49796-ch-mack-400-problems/#findComment-369783 Share on other sites More sharing options...
fjh Posted May 14, 2017 Share Posted May 14, 2017 Yup me too however ,this being an intermittent miss makes me doubt ! vthings happen thou Quote Link to comment https://www.bigmacktrucks.com/topic/49796-ch-mack-400-problems/#findComment-369784 Share on other sites More sharing options...
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