TR Fuel pump relay and wires getting hot | FerrariChat
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TR Fuel pump relay and wires getting hot

Discussion in 'Boxers/TR/M' started by Testarossa Lover, Sep 10, 2013.

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  1. Testarossa Lover

    Testarossa Lover F1 Rookie
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    Dec 31, 2006
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    #1 Testarossa Lover, Sep 10, 2013
    Last edited: Sep 10, 2013
    Hi guys,

    After getting her back I noticed delay in starting her and the following took place:

    1. While driving she died. Pulled over, she cranked over but no start, I reached to the fuel pump relay and it was super hot, I changed it with another she fired up.

    2. I bring her home and tried to start her up and all I got cracks and finally she fired up.

    3. Today in cold start, she started as normal as before, I let run and drive her around and the fuel pump relay got hot again. I shut her off and tried to restart and she struggles again but did fire up after contentious cranks.

    Power is normal and no hesitation. Anyone has this problem before?

    Thanks in advance.
     
  2. Testarossa Lover

    Testarossa Lover F1 Rookie
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    #2 Testarossa Lover, Sep 10, 2013
    I should add that the fuel pump relays have been by-passed and not on the fuse box.
     
  3. Steve Magnusson

    Steve Magnusson Two Time F1 World Champ
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    #3 Steve Magnusson, Sep 10, 2013
    Are the female spade terminals (that attach to the male spade terminals) only crimped, or crimped and soldered, to their respective wires? The current passing thru the terminal 30-to-87 path is HUGE (~10A) -- so they need to be soldered to prevent excessive heating (and even then the relay will run hottish anyway becuase of the non-zero resistance of the switch contacts inside the relay).
     
  4. Melvok

    Melvok F1 World Champ
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    #4 Melvok, Sep 10, 2013
    Are the fuelpumps hot too ?
     
  5. Testarossa Lover

    Testarossa Lover F1 Rookie
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    #5 Testarossa Lover, Sep 10, 2013

    Hi Steve, the socket shows signs of heat. I found two fuses (25 & 30 A). Last time this happened, it shut down one bank. I had fuse wire repaired and fuse replaced. I will post pic.
     
  6. Testarossa Lover

    Testarossa Lover F1 Rookie
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    #6 Testarossa Lover, Sep 10, 2013
    Hi Mel, I didn't reach down below to check things out with the fuel pump. These are the original fuel pumps and she has about 44,000 miles now :)
     
  7. Testarossa Lover

    Testarossa Lover F1 Rookie
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    #7 Testarossa Lover, Sep 11, 2013
    Last edited by a moderator: Sep 7, 2017
  8. turbo-joe

    turbo-joe F1 Veteran

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    #8 turbo-joe, Sep 11, 2013
    let the pumps run and meassure the ampere what they need before changing them
     
  9. Testarossa Lover

    Testarossa Lover F1 Rookie
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    #9 Testarossa Lover, Sep 11, 2013
    I started the overnight cold, she cracked over as usual with no issues. I let her warm up up to the point fans came on. I held both of the relays in my hand, I noticed 7-12 side getting much hotter than 1-6 side. In fact, the red wire and the fuse pocket was so hot that you could not hold it too long. the heat starts at the fuse pocket and to the socket.

    This jut happened to be the side that the body work was done. Are there any ground wires or sockets on the driver side I need to look at since the entire quarter panel was removed and replaced?

    Obviously, if I don't to let her go back to the shop for a minor fixed. The speedometer and the odometer also stooped working within the 1st 20 miles right after I picked her up from the shop.

    7-12 has a 25A fuse, 1-6 has 30A fuse. I am thinking if I put at 10A instead of 25A that is there now, the fuse will blow.
     
  10. Steve Magnusson

    Steve Magnusson Two Time F1 World Champ
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    #10 Steve Magnusson, Sep 11, 2013
    Last edited: Sep 11, 2013
    No, a poor connection at the fuel pump end of things can't cause this problem (because a bad connection there can only reduce the current, or, if the bad connection is there, that is where it would be hot. Either the fuel pump current is high (but I would put a low probability on that) or you have a small resistance near the relay and/or fuse holder in one (or more) of the connections. The heating = I^2 * R -- so, even for a very small resistance (like 0.05 Ohms), the heating can be significant -- because the typical current, I = 10A. As I said before, all of the connections carrying the high current from terminal 30-to-87 need to be soldered (your photos are scary bad :() -- and you should make sure that all of the male-to-female spade connections are clean and tight (even inside the fuse holders). Since the two sides are behaving differently, you could also swap the relays and see if the problem follows the relay or not.

    You can't use a 10A fuse (too close to the normal operating current and will blow on start-up of the motors) -- the stock fuse is 15A or maybe 20A IIRC. 25A or 30A are too high to use, and suggest that this was a bad solution for the real problem of the heat (these fuses are thermal devices so a really hot 20 A fuse will blow well below 20A).


    +1
     
  11. Testarossa Lover

    Testarossa Lover F1 Rookie
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    #11 Testarossa Lover, Sep 12, 2013
    Thanks so much for your help!

    It was the fuse pocket. Before installing the new socket, I soldered the ends before crimping them together. She is back to normal with no issues... :)
     
  12. ozziindaus

    ozziindaus F1 Veteran

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    #12 ozziindaus, Sep 12, 2013
    Another notch on the belt for Mr Steve Magnifisson
     

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