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 Dominick Your Own Question
Dominick, Marine Mechanic
Category: Boat
Satisfied Customers: 1009
Experience:  25 Years Experience as Mechanic, 20 Yrs Boat Yard Owner/Mechanic, Factory Certified
Type Your Boat Question Here...
Dominick is online now
A new question is answered every 9 seconds

5L Volvo Pinta starts, but only runs until carb is empty.

Customer Question

5L Volvo Pinta starts, but only runs until carb is empty. Fuel pump relay 85 and 86 gets power only in the start position. So, fuel pump is only energized during starting. What safety feature or switch is preventing power from reaching the 85 and 86 terminals of the fuel pump relay when the engine is running?
Submitted: 1 year ago.
Category: Boat
Expert:  Tan replied 1 year ago.

Hello. My name is Tan.

Once the engine starts the fuel pump relay is energized by the alternator. Check the green wire coming off the alternator does it have voltage when engine is running?

Expert:  Tan replied 1 year ago.
Customer: replied 1 year ago.
I will have to connect the earmuffs and run it to see.
But, if that is the case, then when the alternator goes bad, the fuel pump would stop running. That does not sound logical.
Customer: replied 1 year ago.
Why wouldn't the energy from the battery continue to energize the fuel pump relay and keep the motor running so you could get back to land?
Customer: replied 1 year ago.
I see your logic looking at the diagram. But, it still seems like a poor way to design an electrical system for powering the fuel pump in a key-on position.
Expert:  Tan replied 1 year ago.

The way the relay works is the cranking the engine energizes a coil in the relay connecting battery power to the fuel pump. So you have 2 sources to power the relay start circuit and the alternator. They look at it like if the alternator quits you won't run the boat any way as the battery will go dead. You can blow the ignition fuse and the engine will quit running. There are allot of things that can go wrong and strand you.

To get back to port all you would have to do is use a jumper wire going from a 12 volt source to run the fuel pump. If a mechanical pump quits you are done.

Customer: replied 1 year ago.
Right now, I have the fuel pump off. When I energize it, it runs and creates a vacuum on the inlet side.
I will first pull the alternator and take it to be checked at the local O'Reilly's.
I will get back with you, Tan.
It may be tomorrow.
Customer: replied 1 year ago.
I am in the process of draining and flushing the fuel cell while I have it apart.
Expert:  Tan replied 1 year ago.

Ok keep me posted. I like to do the run test and check voltage at the alternator and the relay you could have a blown diode in the harness. So if the alternator checks good then you have to check for voltage at the relay with engine running. If no voltage then the diode in the harness is bad.

Expert:  Tan replied 1 year ago.

Could I get the engine model number please to be sure I have the correct model please?

Related Boat Questions