2009 GU713 MP7 Question

[fg61]

Hi guys I have a 2009 gu713 tandem dump with a mp7. I am having some sporadic starting issues. Happens every so often cold and warm. It cranks cranks . Sometimes it takes 3 of 4 tries for it to start. Truck has 35,000 miles. Any feed back would help. Thanks

[Fran3682821]

I got the same motor in my truck MP7 the first thing you should do is take it to a dealer and get a bubble test done for the injection cups that is a common problem for these motors that causes the motor to loose some power and hard to start. But once what happened to me I had been to the mack dealer for a check up performed the bubble test and everything was fine. The following week my truck on occasion maybe twice a week would be hard to start like yours 3 to 4 tries to get it to start. I left it alone and then the following week a sensor for the fuel pressure installed in the filter housing coming out of the top of my fuel filter it resembles a rubber diaphram completely let go fuel began pouring out the top of the fuel filter housing. Once I changed that I never had a problem with the truck starting. I think air was getting in by a small crack in the rubber diaphram making air bubbles. I'am not a top expert but thats what happened to me.

[shortstack]

As already mentioned, injector cups were a problem on these engines. Once updated they don't seem to give anymore problems. That would be my guess. Trey