Fuel pump relay getting really hot and burning the fuse box?

Tiny
_.NICK226._
  • MEMBER
  • 2008 BUICK LUCERNE
  • V6
  • 2WD
  • AUTOMATIC
  • 90,000 MILES
Fuel pump relay getting really hot and burning the fuse box not the seat causing the problem like other people have the seat is off with a new fuse box and fuel pump still gets hot not really sure what else it could be.
Thursday, May 1st, 2025 AT 4:44 PM

12 Replies

Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 54,137 POSTS
I checked out the wiring diagrams and it looks like the system is pretty basic, one relay, one fuel pump, I would look at the G403 ground which is at the right front wall of the luggage department and if that looks okay it would replace the fuel pump, also, you may need to clean and enhance the connections at the fuse panel where the fuel pump relay resides. Luckily there is a trap door in the trunk so you can get to the pump without removing the gas tank. Replace the relay as well. Check out the images (below). Please let us know what happens.
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Friday, May 2nd, 2025 AT 10:05 AM
Tiny
_.NICK226._
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  • 19 POSTS
I changed the fuel pump and checked the ground looks good and cleaned the connections and still have the same issue.
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Monday, May 5th, 2025 AT 3:28 PM
Tiny
KEN L
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Did you swap out the relay? Also, relays will get warm but not hot. The reason for the heat is high amperage/voltage draw through the relay. You may have high resistance in the wire which is not common.
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Tuesday, May 6th, 2025 AT 9:55 AM
Tiny
_.NICK226._
  • MEMBER
  • 19 POSTS
I did swap out the relay and didn't fix the issue and the relay wasn't warm I used a temp gun and it was reading 180 ish so im just going to use a bypass kit but I need to find the power wire and single wire to the fuel pump any help finding those 2 wires?
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Sunday, May 18th, 2025 AT 2:34 PM
Tiny
KEN L
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This car has an oil level and pressure sensors what can shut off the fuel pump, the ground for the sensors is G112 lower left of the engine, I would check that ground to make sure it is good, the fuel pump power wire is "GREY", and I would check the ground for the fuel pump which is at the right front wall of the trunk (black) please let me how it goes.
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Sunday, May 18th, 2025 AT 6:12 PM
Tiny
_.NICK226._
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  • 19 POSTS
I checked the ground and it looks good. Do you know what color the signal wire is?
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Monday, May 19th, 2025 AT 10:47 AM
Tiny
KEN L
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Yes, its grey.
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Tuesday, May 20th, 2025 AT 8:40 AM
Tiny
_.NICK226._
  • MEMBER
  • 19 POSTS
I thought the power wire was grey.
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Tuesday, May 20th, 2025 AT 9:09 AM
Tiny
KEN L
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It is, sorry I miss understood, it is the darkgreen/white wire
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Tuesday, May 20th, 2025 AT 9:51 AM
Tiny
_.NICK226._
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  • 19 POSTS
Okay, thank you.
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Tuesday, May 20th, 2025 AT 12:22 PM
Tiny
_.NICK226._
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  • 19 POSTS
How did you find out which one was which?
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Tuesday, May 20th, 2025 AT 12:23 PM
Tiny
KEN L
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I looked at the wiring diagrams.
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Thursday, May 22nd, 2025 AT 9:36 AM

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