Problem – the bubble on the fuel system will not keep firm. It keeps losing prime. I looked at all hoses and connections. They looked fine. I replaced the prime bubble. Then determined the problem is possibly in the fuel pump.
I've then removed the fuel pump and opened it. Inside the fuel pump there are two quarters size clear, thin, plastic parts. These parts are in the middle of the fuel pump between the two diaphrams connected by a little rubber piece. These two pieces were falling apart and useless.
I know I need to replace these parts obviously, but could this be the problem causing my priming issue?
Can I replace these parts without replacing the entire fuel pump?
You must have Adobe Acrobat reader installed to use this manual. If you scroll down to the lower part of the opening page, you will see the various engine components in red. Click on the one you want and when the first page opens, click on the "Save As" icon at the top LH corner of the page and you can save it to your computer.
I would talk to your Merc dealer and question them about the repair kit for the pump as it says in the service manual that the parts are replaceable. See section 3C-38.