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    1991 Force 90hp starting problem

    Updates: Now I have figured out something. 1. The "POP" when I first run the motor could come from the mis-adjusted timing and linkage. I have strictly followed the stickers and now the "POP" never showed up. 2. The hard-start is due to the idle mixer. It was set as 1 1/4 to 2 rounds, which are...
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    1991 Force 90hp starting problem

    The models is 908F90C. My thought is someone has replaced the fuel pump with a wrong one. But as I dig out, it seems there is no tracks showing they are the replaced one. But about the fuel pump, there are four holes, 1-in, 2-out, 3-air port connected to engine with a hose, 4-another air port...
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    1991 Force 90hp starting problem

    Updates: I rebuilt the fuel pump, but I suspect the pump is not for this engine. The pump shall be installed on the base with a air hole to pump into the fuel pump, as I watched the youtube videos. To me, it seems that someone has just installed a wrong fuel pump to this motor. Please confirm...
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    1991 Force 90hp starting problem

    Big thanks. Exactly what I need!
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    1991 Force 90hp starting problem

    Updates: The unstable idling problem has been identified. It's fuel pump problem. The fuel pump doesn't work or barely work. After idling good for a while, the idle speed rises up and then finally bogs down. If I keep pressing the bulb while it's running, it idles perfectly as long as I want...
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    1991 Force 90hp starting problem

    That's awesome tip, thanks. Will test it out very soon.
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    1991 Force 90hp starting problem

    Thanks Jerry, I think your ways work, although I didn't do the tape and use the clamps instead. The muffs need to be tight and water pressure needs to be high to push water to the pump. Now for updates: The motor runs very good, unless there needs minor adjustment on the idle speed and idle...
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    1991 Force 90hp starting problem

    Thanks everyone for the good points. I followed the sticker again. I don't know what make the difference. But the motor starts normally now. The main changes include: 1. release and re-tight the throttle arm. Make sure they close or open together. 2. Re-do the timing light and make sure it's on...
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    1991 Force 90hp starting problem

    What is a flywheel key?
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    1991 Force 90hp starting problem

    I jumped the engage trigger, to make sure that it can be cranked even if it is engaged in full throttle. This is to set the timing for 28 deg at full throttle. But accident happened. I forgot to put it in neutral, and cranked it started. It started so violently and I shut it down just in time...
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    1991 Force 90hp starting problem

    This is the ignition, it seems not the Thunderbolt? "Idle speed is set as the mark is right below the touch point" - I mean, I set the cam just touch at the stopper with the mark on the stopper. Then I adjust the idle screw to advance the timing and the mark is just below the stopper. This was...
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    1991 Force 90hp starting problem

    These days I am working on my back up engine. 1991 Force 90 HP, 3 cylinder The top piston position is at 0 deg correct. The full throttle is set at 28 deg with help of timing light. The idle mixture is set 1 1/4 turn from touch position. Idle speed is set as the mark is right below the touch...
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    bouncing Tac at idle

    TAC works very good above around 1500 rpm. Very solid and stable, calibrated by signal generator. However, when at idle, it bounces around 800-1000 rpm, not abrupt type but not stable. I was using my multimeter to check the signal too and found the same problem. At idle speed, it reads random...
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    Mercury inline primary pick up 4-6, which is better, 4 or 6?

    Thanks everyone for your feedback, always. Whenever I am not able to get on water, I'd like to find some trouble with my boat. So my boat works good last season. It has 1000rpm idle non-engaged, 650 engaged, 5000rpm at WOT with 17 pitch on a 17 ft boston whaler. The powerhead is new, I mean...
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    Mercury inline primary pick up 4-6, which is better, 4 or 6?

    My motor is 1977 mercury 1150, serving me well, except it has to be set around 1000 rpm not engaged on idle to not bog down. If setting at 800 rpm idle non-engaged, it has 10% to bog down in some certain situation, such has rough water area. When engaged, it's always 650-700 rpm. I've read...
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    Mercury inline 6 distributer rewiring screw plug grease

    It's nothing wrong with the wiring, it's just too old for 40 years. So my question is the grease or whatever in the distributor cap hole where the spark wire crewed in. What is that? I guess its not dielectric grease. It maybe the regular grease to keep water out? It's pretty thick and sticky...
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    Propeller size for 1977 mercury 1150

    Tacho is accurate. Calibrated with a signal generator. Motor running sounds very healthy. Idling trolling very good too. It can jump to run right away. I haven't tried different trim though. Does that play a big difference on RPM? I didn't play with trim very much. Just trim it to bottom and...
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    Propeller size for 1977 mercury 1150

    My boat is 1977 boston whaler montauk outboard: 1977 inline 6 1150 propeller: solas 13.25 x 17 RPM: 4600 Boat runs very good now, no issue so far. So I need to change 17 pitch to 15 pitch, which looks very low to me. Any comments please? Thanks.
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    When opening throttle, inline 6 speeds up for 20 s and then lose power

    hey, guys, found the problem after replacing the fuel pump and filter. It's the fuel line blockage. The original prime bulb fuel line has inner line separated from the outer line and the inner layer stacked up together, which forms a tiny hole allowing fuel to pass by. I replaced the all the...
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    When opening throttle, inline 6 speeds up for 20 s and then lose power

    (typing error, Deleted)
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