Fuel pump not working

Tiny
JUN841NC
  • MEMBER
  • 1995 TOYOTA COROLLA
  • 1.6L
  • 4 CYL
  • 2WD
  • 336,875 MILES
What is the possible causes for burnt fuel wires? Recently had to remove pump because I thought it was faulty just to find out that the wires (positive red and negative black) connected from the pump to the outlet power supply has burnt out. Removed those wires and plug and tested the pump outside of the tank and it worked. Please help. Is this normal or very dangerous?
Monday, October 12th, 2020 AT 9:22 AM

3 Replies

Tiny
STEVE W.
  • MECHANIC
  • 13,324 POSTS
It is somewhat normal, but not a good thing. What usually happens is that the fuel pump starts to fail and draws a bit more current. That in turn causes more heat in the wiring and connectors. Then after a short while the heat causes thermal cycling around the connector and air an moisture get in. The resulting corrosion creates resistance in the connector. That creates more heat and the cycle progressively gets worse until the metal in the connectors starts to get weaker from the constant cycling and the connector gets looser, then either the pump fails or the wiring gives up. When I do a fuel pump I always check the connections to see if they have any heat damage. I also replace the pump unless it was just replaced with a good unit. In this case I would replace the wiring pigtail and then test the current draw of the pump, Common pumps like yours draw about 4-6 amps if they are okay, Higher and I would replace the pump.
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Thursday, October 15th, 2020 AT 11:43 AM
Tiny
JUN841NC
  • MEMBER
  • 18 POSTS
Thanks for the input. I changed the pump about 6 months ago. What causes my pump to go that fast every year? I change it about twice. Also I tested it and it was pumping fine, is it necessary for pump replacement? I put about 3 or 4,000 kilometers on it for the 6 months.
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Thursday, October 15th, 2020 AT 11:43 AM
Tiny
STEVE W.
  • MECHANIC
  • 13,324 POSTS
If this is the first time you noticed the bad wiring it's possible the connector has been failing for a while and finally got bad enough to melt the wiring. I would check all of the wiring that feeds the pump to be sure there isn't another area that is failing. Then there is the issue of the pumps themselves, I don't have much luck with many of the aftermarket pumps when it comes to longevity so I try to get OEM if possible. Another thing is that you don't want to run the pump in low fuel often, the pump uses the fuel going through it for cooling and running the tank down low many times can cause the pump to get warm and cause problems.
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Thursday, October 15th, 2020 AT 11:43 AM

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