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  1. #1
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    Mercury 150 XR6 lost 600 -800 RPM's

    Motor is a 2002 Serial # 0T556067. Boat started to act up with difficulty starting during the summer and one morning felt sluggish out of the hole and at WOT would only get about 4800 RPM at 49MPH. Boat typically will run 60MPH at 5600RPM. Compression is 115 on all 6 cylinders. Took the boat to the dealer who thought it was a fuel starvation problem so after a $1,500 bill I took it to the lake and immediately had the same problem. Took it back to the dealer and they said they could not find a problem after testing everything. I talked to another marine shop and they thought it could be the coils so I swapped all 6 and ran her again this weekend with no change in performance. When accelerating it feels like it doesn't have the power it used to and can feel the engine surging or struggling at times. Frustrated to say the least and hoping someone can point me in the right direction on how to fix this problem. BTW, Motor was rebuilt 2 years ago.



    AL Greco

    Triton TR-186

  2. Member
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    #2
    I had a similar problem a few years ago. Started checking the obvious and replacing the easy things. Same problem. Asked around and guys said it sounds like a bad fuel line. Changed it out 2 times. Same problem. What my problem was, a tiny air leak it the tap off my fuel line that goes to my kicker. They both use the same gas tank. The piece of fuel line was 2 inchs long. Replaced that and all was fine.

  3. Member
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    #3
    I had the fuel lines replaced and the marine shop put in new hose from the bulb to the motor, i hope your right as this is driving me crazy trying to figure this out. I spoke to another shop and they are going to meet me out on the lake and see what it is doing as they say they might not be able to find the problem with it in the shop bay.



    AL Greco

    Triton TR-186

  4. Mercury 3L/4 Stroke/Verado Moderator EuropeanAM's Avatar
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    #4
    Need to start back at the basics- bound to be Compression, Spark, or Fuel Quality/Delivery.

    Don't overlook the trigger (pretty common to see intermittent trigger problems, actually in the HARNESS for the trigger) on this vintage.


    Dual Mercury Master Technician- for Mercury Outboards, Mercruiser and Mercury Racing at European Marine in Greenville, SC.
    Still consider myself a "Marine Apprentice" after 47 years (learn something new every day).
    Mercury Parts, Mercury Outboards, Smartcraft & Accessories, Injector Service, TDR Reeds- BBC Sponsor

  5. Member
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    #5
    If you still have the quick disconnect at motor do away with the connection and put a hose splice in there as I have seen those suck air.
    Bruce Phillips
    1995 190 DC champion ......1995 200 xri merc

  6. Mercury 3L/4 Stroke/Verado Moderator EuropeanAM's Avatar
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    #6
    Or better yet- straight from the primer bulb, all the way to the pulse fuel pump.


    Dual Mercury Master Technician- for Mercury Outboards, Mercruiser and Mercury Racing at European Marine in Greenville, SC.
    Still consider myself a "Marine Apprentice" after 47 years (learn something new every day).
    Mercury Parts, Mercury Outboards, Smartcraft & Accessories, Injector Service, TDR Reeds- BBC Sponsor

  7. Member
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    #7
    Fuel connection is as Don describes directly from PB to fuel pump. Won't get a chance to run it with mechanic until mid November but will make sure he takes in account all the suggestions received, really appreciate it!



    AL Greco

    Triton TR-186

  8. Member
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    Jan 2013
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    Hamilton, Ontario
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    #8
    Could it be a vent line restriction or a pick up tube restriction? Fuel tank access to check your vent line, and tank

    http://www.bbcboards.net/showthread.php?t=478158
    Last edited by Bob McKenzie; 10-25-2018 at 11:38 AM.

  9. Member
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    #9
    Another thing to check, some boats had it and some don't....Check the fitting that the fuel line connects to at tank as some of them had a one way check valve and it will restrict fuel flow as the spring against the ball goes bad and lets the ball go to far and restrict fuel flow.
    Bruce Phillips
    1995 190 DC champion ......1995 200 xri merc