KCDShop Posted March 4, 2022 Share Posted March 4, 2022 Hey all! First post for me and hoping yall can help me out. Ive got a fleet of 2021 Mack LR 64 (600) with MP7 engines. We had to drop the tank on a unit for a hole repair and after reinstalling the tank we cannot get the truck primed. We've done the filters, put air to tank and got fuel to the pump. We've used the check valve, ran diagnostics in PTT, we just can't seem to figure it out. Any ideas? Hoping to get some advice on our next direction. Thanks! Quote Link to comment https://www.bigmacktrucks.com/topic/69324-mp7-wont-prime-any-ideas/ Share on other sites More sharing options...
mrsmackpaul Posted March 4, 2022 Share Posted March 4, 2022 There is a on line service bulletin for the MP7 MP8 and MP10 I just typed "how to bleed a MP7 Mack engine" and it appeared right away So maybe do some googling Sorry I cant be of anymore help as I have no experience with these It does sound like the return side of the system isnt letting the air out but I really have no idea Perhaps look for a plug on the pressure side to get some fuel into the pump, just a guess Paul Quote Link to comment https://www.bigmacktrucks.com/topic/69324-mp7-wont-prime-any-ideas/#findComment-490874 Share on other sites More sharing options...
Onyx610 Posted March 4, 2022 Share Posted March 4, 2022 Need more info…will it start and shut off? Will it start and run like shit for a little and quit? Or does it just crank? Make sure there is nothing in the tank since you had work done to it and recheck all the work you did when reinstalling the tank. Could be pulling air at a connection. Quote Link to comment https://www.bigmacktrucks.com/topic/69324-mp7-wont-prime-any-ideas/#findComment-490876 Share on other sites More sharing options...
Vmac3 Posted March 7, 2022 Share Posted March 7, 2022 Fuel lines switched around on the fuel tank?? 1 Quote Link to comment https://www.bigmacktrucks.com/topic/69324-mp7-wont-prime-any-ideas/#findComment-491100 Share on other sites More sharing options...
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