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  1. Kola16

    Carbed Mercruiser 260 5.7L Missing Above 4000 RPMs

    So I realized that the pressure gauge was definitely not calibrated and was reading lower than it should have for delivery pressure and higher for vacuum. The needle sat at an atmospheric pressure at 3 in. of Hg. I first took the inline fuel filter out. I then calibrated the gauge (calibrated to...
  2. Kola16

    Carbed Mercruiser 260 5.7L Missing Above 4000 RPMs

    This is my setup. The Mercruiser fuel pump part number is 86246. I have the diagram attached and a picture of what my fuel pump actually looks like. I Will take it apart tonight to look at the filter, but knowing the history of my boat, I bet it is clogged as can be since when the Rochester carb...
  3. Kola16

    Mercruiser 5.0 wont start without help getting gas to carb. But runs fine once started...

    It would help to know what the specs of your engine are. For example, year, serial number, checking the fuel pressure between the carb and your fuel pump, is this a new problem and it ran fine beforehand or did you just buy this engine, etc....
  4. Kola16

    Carbed Mercruiser 260 5.7L Missing Above 4000 RPMs

    Got it, thanks for the clarification on the fuel water separator and fuel pump fuel filter being enough filtering. The braided flex hose is CG approved. I'll ditch the fuel filter and rubber hose before the carb and remove the fuel pump to check the filter this evening. The majority of my engine...
  5. Kola16

    Carbed Mercruiser 260 5.7L Missing Above 4000 RPMs

    Really get rid of the fuel filter? The Edelbrock carb install manual calls for it since the Edelbrock does not have a filter in the carb like the Rochester had. If I get rid of that one then the only filter would be the one that is supposedly in the pump. How fine of a filter is the one in the pump?
  6. Kola16

    Carbed Mercruiser 260 5.7L Missing Above 4000 RPMs

    I tried to check the vacuum, but the fuel pump had metal lines running to it on the intake from the fuel water separator. So I took the reading between the tank and the fuel water separator. Is that an okay spot to test it at? It said 4 in Hg. Although I question this cause the gauge needle does...
  7. Kola16

    Carbed Mercruiser 260 5.7L Missing Above 4000 RPMs

    So take the fuel pump apart and look for a filter in it? I ran it today to get a video of the fuel pressure. At idle it was between 4 and 5 PSI. But when i hit the throttle it would drop to 2.5-3 PSI as you can see in the video https://youtube.com/shorts/wZyFibjlJoU?feature=share
  8. Kola16

    Carbed Mercruiser 260 5.7L Missing Above 4000 RPMs

    Oh also I know it is not the shift interrupt switch because I held the little lever spring thing open so it would not trigger it and still the same thing. Okay I will try to check this. I have never heard of a fuel system vacuum before so I will have to Youtube that...I checked my tanks air...
  9. Kola16

    Carbed Mercruiser 260 5.7L Missing Above 4000 RPMs

    Okay long story. So I took it to a mechanic just to run it on the hose real quick to see if he notices anything. He noticed there was rubber dust clogging up my flame arrestor. So while it is running, I take the flame arrestor off, and the RPMs pick up a little at idle. I thought it was an "aw...
  10. Kola16

    Carbed Mercruiser 260 5.7L Missing Above 4000 RPMs

    My mistake. It is getting 12v. I will test the fuel pressure as soon as that kit gets to me (shipping says Sunday).
  11. Kola16

    Carbed Mercruiser 260 5.7L Missing Above 4000 RPMs

    That's what I figured. Thanks! My guess is the prop and weight...
  12. Kola16

    Carbed Mercruiser 260 5.7L Missing Above 4000 RPMs

    So I changed the spark plugs and they were gross. I ran the boat for 6 or so hours and no misses. Of course it runs fine when we're watching. We were trying to see if the interrupt switch was being tripped but we weren't having any misses. The boat was; however, not cruising at its normal...
  13. Kola16

    Carbed Mercruiser 260 5.7L Missing Above 4000 RPMs

    I know what you are talking about i will for sure check it out, thanks!
  14. Kola16

    Carbed Mercruiser 260 5.7L Missing Above 4000 RPMs

    "This one comes with .098/.101 jets (primary/secondary) and .068x.047 rods and the orange step up spring as intended from Edelbrock." From the rebuilder...
  15. Kola16

    Carbed Mercruiser 260 5.7L Missing Above 4000 RPMs

    Yikes! I will send the company that rebuilt the carb a message.
  16. Kola16

    Carbed Mercruiser 260 5.7L Missing Above 4000 RPMs

    That is a good idea, I'll have to get a fuel pressure checker and test it.
  17. Kola16

    Carbed Mercruiser 260 5.7L Missing Above 4000 RPMs

    Hmm that could be an option. The wiring harness looks like the original. I thought the ICM was only for starting, but shows you how much I know.
  18. Kola16

    Carbed Mercruiser 260 5.7L Missing Above 4000 RPMs

    Hello all. My Mercruiser 260 GM 5.7L I/O with the MC-1 Drive sounds like it is missing, or starving for fuel at higher RPMs (4000+). It does it when already on plane, and/or out of the hole. It is happy as a clam at idling and cruising speeds (750-3500 RPMs). Here is all the back info: - All...
  19. Kola16

    Carburetor Overheating. 350 Sputters Out After 30 mins

    My recently rebuilt 350 carbed block has had an issue the last 5 times out on the water. It will be running like a champ for about 20 minutes, then it sputters as if it were running bad gas or out of gas. Thinking it was a fuel issue after the third time, I drained the tank, inspected the fuel...
  20. Kola16

    228 Power Trim Down Works; UP & UP/OUT Do Not

    Hello all! First post of hopefully many! This forum has helped me a lot as I've been a long-time lurker just never got around to creating an account. Anyway, my MerCruiser 228 will lower but, not raise. I have the old 3 button control panel style from 1979. The serial number on the outdrive is...
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