Fuel pump not starting when engine is hot

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  • harold30
    Advanced Member
    • Jul 2011
    • 180
    #1

    Fuel pump not starting when engine is hot

    Hi Guys,

    I have this problem with my car lately when then engine is hot, it will just crank but won't start. What I always do is removed the fuel pump relay and cool it down, put it back again and starts right up. I tried switching with different relay but same thing happen so the relay is not the issue but somewhere else. Could it be a contact or wiring problem? or other else? Can someone point me where to look first.

    Cheers,
    Harold
    Tags: None
    • superj
      Grease Monkey
      • Feb 2006
      • 397
      #2
      like, if you remove the relay and put a spare one in, the car starts immediately? have you tried that or just pulled the relay and let it sit so everything cools off the same?

      that's definitely odd.

        Comment

        • harold30
          Advanced Member
          • Jul 2011
          • 180
          #3
          Originally posted by superj
          like, if you remove the relay and put a spare one in, the car starts immediately? have you tried that or just pulled the relay and let it sit so everything cools off the same?

          that's definitely odd.
          removed the relay and rubbed it with my palms to absorb the heat, after a minute or 2 put it back on and it will start, though most of the time a weak start but still better than just cranking.

          no i haven't tried replacing it with a spare one but instead switching relays from fusebox but since it's warm it won't start.

            Comment

            • Kershaw
              R3V OG
              • Feb 2010
              • 11822
              #4
              Have you tried just waiting a minute or two? Have you verified that your relay rubbing technique is what is causing the car to start?
              AWD > RWD

                Comment

                • harold30
                  Advanced Member
                  • Jul 2011
                  • 180
                  #5
                  Originally posted by Kershaw
                  Have you tried just waiting a minute or two? Have you verified that your relay rubbing technique is what is causing the car to start?
                  I tried waiting 5-10 minutes without opening the hood and it won't start. that's why I always rub the relay to make it start right away. I also tried switching the fuel pump relay with o2 sensor relay without rubbing and they're still warm and it won't start.

                  BTW, I came from a country where it's hot and humid through out the year so the engine won't cool down right away. (IDK if it matters though)

                  Maybe I just too focus on the relay where the problem lay somewhere.

                    Comment

                    • dnguyen1963
                      R3VLimited
                      • Nov 2011
                      • 2648
                      #6
                      If the relay gets that hot then it is drawing way too much current. Check for short in the wire between the relay and the pump.

                        Comment

                        • Seawolf
                          Wrencher
                          • Feb 2015
                          • 270
                          #7
                          This could be caused by other things but it's easy enough to eliminate the fuel pump relay.

                          Make up a short jumper wire with a 1/4" male spade connector on each end, or use a paper clip if you really have to.

                          Next time the car quits pull the fuel pump relay and use the jumper to connect pins 30 & 87 on the relay socket, this will effectively bypass the relay.

                          If the car starts then the relay is the problem, if not then the problem is something else.

                            Comment

                            • harold30
                              Advanced Member
                              • Jul 2011
                              • 180
                              #8
                              Originally posted by dnguyen1963
                              If the relay gets that hot then it is drawing way too much current. Check for short in the wire between the relay and the pump.
                              I always suspected a short somewhere in the wires. Will check it when I have time. Thanks!

                                Comment

                                • harold30
                                  Advanced Member
                                  • Jul 2011
                                  • 180
                                  #9
                                  Originally posted by Seawolf
                                  This could be caused by other things but it's easy enough to eliminate the fuel pump relay.

                                  Make up a short jumper wire with a 1/4" male spade connector on each end, or use a paper clip if you really have to.

                                  Next time the car quits pull the fuel pump relay and use the jumper to connect pins 30 & 87 on the relay socket, this will effectively bypass the relay.

                                  If the car starts then the relay is the problem, if not then the problem is something else.
                                  I'll note and do this next time. Thanks!

                                    Comment

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