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4.3L Fuel Pump will not stop priming - Do I need a new Mechanic?

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  • 4.3L Fuel Pump will not stop priming - Do I need a new Mechanic?

    HI,

    I have a 97' Searay with a 4.3L LXGen+

    I had my mechanic come out to replace the water pump in the I/O, replace plugs, cap&rotor, gas water seperator, gas filter in carb, slave selnoid and oil pressure sensor. After all this, he started the boat and it would run a few seconds and stall. (Prior to his visit I had the boat running and it didn't stall).

    He answer was there's fuel to the carb so the carburetor needs to be rebuilt and he had some fuel in a baggy and showed that I had some particles in the fuel.

    SO.... I agree to have the carb rebuilt and went the extra yard to have the fuel polised.

    NOW... I noticed when I turn the ignition on the fuel pum keeps priming (before all this work, I recall it would humm for a few seconds and stop)..

    I called mechanic and answer I got was ..."Huh..don't know maybe the fuel pump got dirt from the bad fuel"

    The guy who polished the fuel did not find any significant dirt issues with the fuel.

    I now notice that when he replaced the oil pressure sensor there's a sensor right behind it (see pic) and he tied the purple/yellow to another wire (looks purple) - which use to go to the old sensor (looks like he replaced it with one that looks a bit different then the original one).

    Why would he tie these wires together and not put them back on the sensor where they use to go???

    And would this cause the fuel pump to continously prime iteself?

    What issues will I have it I leave it this way?


    Thanks
    CHris
    Attached Files

  • #2
    Re: 4.3L Fuel Pump will not stop priming - Do I need a new Mechanic?

    NOW... I noticed when I turn the ignition on the fuel pum keeps priming (before all this work, I recall it would humm for a few seconds and stop)..
    Coming on for a couple of seconds only happens on EFI engines, you car comes on and shuts off, but not your carbed marine engine.

    The pump only comes on when cranking the engine with the starter and when the oil pressure builts and turns the OP switch on to allow power to the pump.

    Picture is way too small to see any detail, but here is a wiring diagram that shows how the wiring should be set up.

    Click image for larger version

Name:	Fuel Pump Wiring.jpg
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    PS, I don't think I would go back to that mechanic again.
    Don S.


    Please, no PM's (Private Messages) regarding boat/engine problems.
    That is what the forums are for.
    Only forum/moderator issues will be answered in PM's.

    Comment


    • #3
      Re: 4.3L Fuel Pump will not stop priming - Do I need a new Mechanic?

      So why would he have bypassed the oil pressure switch and tie the wires together? I believe this switch is to also help shut the engine off if there was a lost in pressure.

      Before the carb was rebuilt it would run for about 15 seconds and then stall. He came buy and installed the rebuilt carb when I was not home so not sure if after the carb was installed the issue wasn't solved and after some research, I'm thinking now maybe its the oil pressure switch that is bad and he simply bypassed it by tying the wires together (purple/yellow and purple).

      I want to collect as much info here before I call him... my thought is to have him come back and place the wires back on the OP switch.

      Comment


      • #4
        Re: 4.3L Fuel Pump will not stop priming - Do I need a new Mechanic?

        Another question - would bypassing the oil pressure switch cause the fuel pump to continually prime? and is this bad?

        Comment


        • #5
          Re: 4.3L Fuel Pump will not stop priming - Do I need a new Mechanic?

          Originally posted by Chris631 View Post
          Another question - would bypassing the oil pressure switch cause the fuel pump to continually prime? and is this bad?
          It's not just priming, it's running at full output, and yes it's bad. The reason it's setup to not run all the time is a safety issue. If a fire should start and the engine isn't running, you will have the fuel pump running and pumping gas into a fire. Not a good thing.

          The switch is bypassed completely, so the fuel pump runs any time the ignition switch is in the run position rather the engine is running or not.
          Don S.


          Please, no PM's (Private Messages) regarding boat/engine problems.
          That is what the forums are for.
          Only forum/moderator issues will be answered in PM's.

          Comment


          • #6
            Re: 4.3L Fuel Pump will not stop priming - Do I need a new Mechanic?

            Why was the oil pressure switch replaced by the mechanic? I would go someplace else or learn to do it right yourself.
            83 Sunrunner 16.5 120 merc Alpha 1 drive SOLD 8/1/13

            1996 Crownline 202BR
            5.7l EFI 0f791070
            Bravo I drive

            GMC Yukon tow rig

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            • #7
              Re: 4.3L Fuel Pump will not stop priming - Do I need a new Mechanic?

              At the end of the season last year I had no oil pressure reading on my gauge and I asked the mechanic to change the oil pressure sensor. He had a hard time getting it out but was able to replace it and the oil guage worked again.

              After he was done with the job the boat began to stall (did not do this before he touched it). He right away pointed to the carb and I specifically asked if there was anything he might have done to cause the issue - he answer of course = NO.

              Now that I found he bypassed the oil pressure switch (I'm thinking he may have damaged it / cables when removing the oil sensor) - I am wondering if I spent $500 on a rebuilt carb for no reason.

              I called him earlier and confronted him - he played ignorant and claime it was like that and I challenged him since I actually tried to reseated the cable on the pressure switch the day before he arrived.

              Now he says the pressure switch is bad and he'll need to repalce it. I blew a gasket and asked why he would not tell me at the time. His answer was that I was complaining about the cost of the repairs... The switch is $30 , I'm already into $1500 with him for everything what's another $30. I told him it's a safety issue and he started to back peddle. I bet the switch is bad and there was no reason to have the carb rebuilt or the fuel polished.

              Before he changes the switch I will ask him to reconnect the wires to the old one... if the engine stalls and it doesn't after he changes the switch then we now I got had.

              Comment


              • #8
                Re: 4.3L Fuel Pump will not stop priming - Do I need a new Mechanic?

                this guy sounds like a parts changer and salesman instead of a technician. All this stuff is documented how it works and should be wired. You don't misdiagnose and change the wrong part and then bypass things to cover your unsolved issue. It appears that's what your guy did.
                He should have found out what's wrong and fixed it. Now that he has bs'd his way into this position he can't back out. You are not likely to hear much complete truth from this point forward. Although I would love to hear what happens when you confront him with the solution.
                I hope I am wrong and he gets it right for you.
                I look forward to your next post...
                87 Formula F223LS, 2016 383 Stroker, 2019 Davis Unified(HEI) Ignition, Quickfuel Marine 750
                Lake Winnipesaukee, NH

                Comment


                • #9
                  Re: 4.3L Fuel Pump will not stop priming - Do I need a new Mechanic?

                  Oil pressure switch bypassed, owner not informed... That's a really good case to have him charged with culpable negligence. What he did was to put you and your family in a possible situation of grave danger...

                  Ok.. to anwser a few of your questions.

                  It's most probably that he knocked the wires on the switch while changing the oil pressure sender. Not difficult to do. Once that happens and the connection is no longer viable, then the only time the fuel pump gets power is while you're cranking the engine. So for those few seconds the pump is pushing fuel into the carb. Once the engine fires and you release the key back to the RUN position the fuel pump is no longer receiving power, no fuel is pumped. The carb runs the fuel that was pumped during cranking, then stalls (lack of fuel). You crank it again and some more fuel is pumped... and so the cycle goes....

                  DH 'mechanic' comes along and rebuilds your carb (maybe), joins the 2 wires from the oil pressure switch and the problem is solved. Only now the fuel pumps runs continuously whenever the key is in the RUN position. BAD situation, as Don explained.

                  Personally, I'd pay the guy for the other work he did, forget the carb rebuild, and deduce the amount for the new oil pressure switch (which HE damaged). If he challenges it, explain how the MTA (or whatever your equivalent is) would love to hear about his sub-standard workmanship.... I don't think you'd hear from hm again....

                  Chris........
                  xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
                  The world takes on a whole new perspective when viewed from 100’ below.
                  1972 Bertram ‘Bahia Mar’ 20
                  2006 Mercruiser 4.3MPI (0W617679) w/Alpha One Gen II (0W829301)
                  (Original - 1972 '165' In-line 6. Previous - 1994 4.3LX)


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                  • #10
                    Re: 4.3L Fuel Pump will not stop priming - Do I need a new Mechanic?

                    Well I removed the jumper and placed the wires back on the switch and after about a minute the engine stalls and I hear no humm from the fuel pumo when I turn the ignition on.

                    I ordered a new switch and will replace it myself... I'm told the new switch is configured with a harness and will require me to splice the wires (I think I can handle this). I should get the switch tomorrow and I suspect everything will run as it should and I will be calling the mechanic to have it out with him. This is a local guy I used for years... can't believe he would pull this on me.

                    Comment


                    • #11
                      Re: 4.3L Fuel Pump will not stop priming - Do I need a new Mechanic?

                      He may have thought he was saving you the cost of defective oil pressure switch, and maybe is not a safety-first thinker. Or maybe he rigged it for some reason to troubleshoot after noticing the switch did not work and forgot about it.
                      2002 Bryant 188 4.3MPI

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                      • #12
                        Re: 4.3L Fuel Pump will not stop priming - Do I need a new Mechanic?

                        Originally posted by Maclin View Post
                        He may have thought he was saving you the cost of defective oil pressure switch, and maybe is not a safety-first thinker. Or maybe he rigged it for some reason to troubleshoot after noticing the switch did not work and forgot about it.
                        Even if one of those was the case, I don't think I would want them working on my boat.
                        Don S.


                        Please, no PM's (Private Messages) regarding boat/engine problems.
                        That is what the forums are for.
                        Only forum/moderator issues will be answered in PM's.

                        Comment


                        • #13
                          Re: 4.3L Fuel Pump will not stop priming - Do I need a new Mechanic?

                          I agree, shows some gaps in professionalism skills for sure.
                          2002 Bryant 188 4.3MPI

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                          • #14
                            Re: 4.3L Fuel Pump will not stop priming - Do I need a new Mechanic?

                            I was able to install the new oil pressure switch today and she's no longer stalling. Turn the ingnition on and the fuel pumps hums for about 30 secs and stops (can't remember how longer it hummed in the past) - but once she starts she doesn't stall.

                            So... I contacted my mechanic and had it out with him.. He deceived me and placed my family at risk by bypassing the fuel pressure switch. Unlikely he will offer to repay me any of the $700 I spent on unnecessary repairs.

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                            • #15
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                              Re: 4.3L Fuel Pump will not stop priming - Do I need a new Mechanic?

                              I was able to install the new oil pressure switch today and she's no longer stalling. Turn the ingnition on and the fuel pumps hums for about 30 secs and stops (can't remember how longer it hummed in the past) - but once she starts she doesn't stall.
                              You still have a problem.

                              It should NOT run at all when you first turn the key to run. You have something wired wrong somewhere.
                              What was the PN of the switch you ordered?
                              Don S.


                              Please, no PM's (Private Messages) regarding boat/engine problems.
                              That is what the forums are for.
                              Only forum/moderator issues will be answered in PM's.

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