Logo
FULL SITE MENU

Fuel Pump Relay Melted

T

Tuff E Nuff

New member
I have a 2009 Volvo Penta 5.7 Gi. Last week I replaced the fuel pump and everything was working fine. After running the boat for a couple hours I turned the boat off and the fuel pump continued to run even with the key off. After turning the battery off it stopped. The fuel pump relay switch was melted. What would have caused this problem?
 
It was most likely caused by a low voltage issue which caused the pump to draw more amperage which over heated the contract points and welded them together. Corroded relay points, dirty contectors at the relay or maybe a low battery. Clean all the connections, be sure the battery is fully charged and install the right relay (marine quality). I assume that the new pump had the same electrical requirements as the old one had. Hope this helps.
 
I put the new relays in the boat yesterday and checked the voltage going to the relay plugs. I am getting 12.6 volts when the battery is on. After I put the new relay in the boat cranked up normally. After running for about 2 minutes the fuel pump starting to whine (this is a brand new fuel pump that I installed last week) After another minute or two of running I shut the engine off and pulled the relays back out. The relays were hot and the fuel pump seemed hot to only be running a few minutes. I also smelled something like electrical burning.
 
A bad "new" fuel pump drawing too much current? I'd exchange or get another. Also, check the leads for their integrity. Make sure the "hot" wires are not shorted to ground, burnt, or corroded along with the connectors/plugs. Not an electronics whiz by any means but I would think the circuit should be fused which should go before taking out a relay.
 
KCJ makes a great point.
If you have a continuity issue (at either the Pos or Neg side), voltage may be lowered.
The same load in Watts will cause an increase in Amperage.
Amperage is what over-loads a circuit.

Tuff E Nuff said:
............. I turned the boat off and the fuel pump continued to run even with the key off. After turning the battery off it stopped. The fuel pump relay switch was melted. What would have caused this problem?
Click to expand...
The N/O oil pressure switch is on the low current side of the relay.
The relay contacts carry the electric fuel pump load.
The melting of the relay would point to too much amperage passing through it.


.
 
I ran the boat yesterday and the relay never got hot and the boat ran perfect. However, the fuel pump operated normally when you turned the key to accessory, (filled the filter up with fuel) then when I crank the engine the pump sounds like it is filling the filter up again and doesn't stop. Just a constant whine. This is on the left fuel pumper under the fuel filter (I believe its the low pressure pump). If I unplug the connector wires to the pump the noise stops and the boats continues to run. Any idea what is causing this sound or what is happening?
 
Also, sometimes when I crank the boat the boat turns over and runs like normal, but when I let go of the key to return it to accessory it shuts off. I have to crank it a couple times and keep the key in the run position for a few seconds then I am able to let go of the key and it continues to run. Would the ignition have anything to do with my fuel pump issue?
 
Back
Top