How JustAnswer Works:
  • Ask an Expert
    Experts are full of valuable knowledge and are ready to help with any question. Credentials confirmed by a Fortune 500 verification firm.
  • Get a Professional Answer
    Via email, text message, or notification as you wait on our site.
    Ask follow up questions if you need to.
  • 100% Satisfaction Guarantee
    Rate the answer you receive.
Ask Jason Your Own Question
Jason, Marine Mechanic
Category: Boat
Satisfied Customers: 15674
Experience:  Degree in Marine Technology. Gas and diesel marine mechanic.
Type Your Boat Question Here...
Jason is online now
A new question is answered every 9 seconds

Is there a on/off switch or valve on the Volvo Penta MD7A?

Customer Question

Is there a on/off switch or valve on the Volvo Penta MD7A? I've been trying to start one that has been siting for 3 years and having no luck. I changed all the filters and oil. Sucked out the diesel fuel and add new. Blew out the lines for anything that mat have been stuck in them.
When trying to prime with the fuel pump lever it wont. The fuel won't even get to second fuel filter. We even topped that filter off prior to priming. We also were hand cranking the engine to no prevail.
I spoke to a friend who said there is should be a ON/OFF switch or valve that is holding us back. If there is can someone explain to me where, and if not any suggestions on starting this beast.
Submitted: 1 year ago.
Category: Boat
Expert:  Joe replied 1 year ago.


Thank you for allowing me to assist you, my name is Joe and I will be happy to assist you with your concern today.

"When trying to prime with the fuel pump lever it wont", I presume this has the mechanical fuel pump and that you have removed and are trying to manually work the arm? Disconnect tje output fuel line from the pump and with the pump arm being moved it should come out the output, if not there is a restriction, leak or bad fuel pump, with that said mechanical fuel pumps that sit for years are known to go bad and may need to be replaced. You can simply create a suction on the fuel pump input line and if you pull fuel with no loss and no air (once primed out) and nothing out would would then have shown the problem as the pump.

Thank you!
- Joe

Please rate my answer when ready. Bonuses are appreciated.
If for any reason you are not satisfied please reply back to me for further assistance to which I will be glad to help you. If you have any problems for any reason please reply back and let me know.
Thanks again for using justanswer and have a great day!

If you need any further assistance you can reply back at any time for my help.
I'd be happy to answer any other questions you have even if not related.

Expert:  Jason replied 1 year ago.

Hi Fred, my name is Jason.

The engine needs 2 things to run, compression an fuel. If it will not prime with the fuel pump lever chances are the fuel pump has a bad diaphragm, as it should be pushing fuel through it. These engines will run on WD40, and burn it as a fuel. So start by removing the air cleaner, have a helper turn the engine over, and spray WD40 into the intake and let me know if the engine will start and run on that or not.