The 300 cummins starts and idles fine. Goes into high idle fine and even revs if not under load. Once in gear with brake set or driving it will stumble, rebound and then stumble again in a cycling way like running out of fuel.
My diesel mechanics scan tool shows no fuel pressure from any aux fuel pump, but it does show vac. pressure from hi pressure pump drawing fuel to the engine. Dont know for certain there is an aux pump, but assuming there is because tank is over 20 feet from the engine and seems should be one. Manual makes no mention of one tho?
On top of tank there are number of wires going thru a portal into the tank and seems like more than needed for sending unit.
Two good diesel mechanics believe Cumminns ISB300 engines have an aux pump, but could they be wrong?
Manual does mention that clogged tank vent can give issues and guess id better check it out, but didnt ghink could be culprit.
Hoping might be some good techs on the Monaco group provuded me, but busy next couple days. Thanks much for replies and advice.
