Recent content by Bernt

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    Johnson 3 cyl 70 hp, 1986. No vacuum at one carburator

    Thanks. I have the pulses, pump works fine. So even if that fuel pump pulse connector to the crankcase would be fully open to the atmosphere, it would not affect vacuum for carbs. Same for the fuel spillage line, correct? Desperately seeking easy fixes to my problem 😉.
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    Johnson 3 cyl 70 hp, 1986. No vacuum at one carburator

    Thanks for all wisdom. How is the design of the vacuum tube going to the fuel pump? It extends from the lower part of the block, is it therefore (only) connected to the lower crank case? If it would be leaking, that would explain the issue? Also like to better understand what I assume is a...
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    Johnson 3 cyl 70 hp, 1986. No vacuum at one carburator

    Correct, nothing. The paper is not sucked in, nor pushed out. No impact on rpm. On the other 2 cylinders, it is clearly sucked against the carb air inlet and rpm drops. ( we test without air box installed, but it is very open and no filter, so it makes no impact on engine behaviour I assume?)...
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    Johnson 3 cyl 70 hp, 1986. No vacuum at one carburator

    Ok, now I understand. Thank you. Sorry for not getting it first, but this is why I posted a question. Trying to grasp tech terms in a foreign language doesn't help.....
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    Johnson 3 cyl 70 hp, 1986. No vacuum at one carburator

    Thanks to all. What I don't understand is why issues like spun bearing, leaking crankcase or leaking skirt only ellimate proper vaccum at One carb inlet? Isn't the crank case just one vessel, so a leak would kill suction thru all carbs? Getting back to the Reed valves, assuming I'm wrong and...
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    Johnson 3 cyl 70 hp, 1986. No vacuum at one carburator

    Could that reduce vacuum on one carb? Not an expert but assume it's the rings that seals off and creates vacuum. If compression is good then skirt condition would not relate to my issue?
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    Johnson 3 cyl 70 hp, 1986. No vacuum at one carburator

    Thanks Jimmbo. OK lesson learned in regards to start gas. No, I can't see any sign of leaks there. But I understand your point. We did change the gasket between case and intake plate while we inspected the Reed valves ( thanks, now I know the name of them). Yes, strong spark, tested with spark...
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    Johnson 3 cyl 70 hp, 1986. No vacuum at one carburator

    Hi all, This engine idles Ok but lacks power under load. So after checking zillions of things incl. ignition, spark plugs, fuel system and compression test (even on all 3) we have found the following issue for which we have no explanation: There are 3 carbs/cylinders. Removing the air inlet...
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    Johnson 70 hp 3 cyl / 2-stroke dies when giving more throttle

    Great questions. We replaced some but not all fuel lines. They are not blocked and not leaking, but some are old and stiff. We will replace all. Yes floats and seats/needles are OK. Propeller not changed but the boat is larger, point taken. Propeller is 13,75x 17, but if that would be an...
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    Johnson 70 hp 3 cyl / 2-stroke dies when giving more throttle

    Yes, they are clean. We where certain after first check/ cleaning of all 3 carbs, but after still having issues we checked them one more time. All still clean and in very good general condition. But your question is very valid, dirty carburetors seems to be a likely reason. And the engine worked...
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    Johnson 70 hp 3 cyl / 2-stroke dies when giving more throttle

    Thanks, OK we will try. So the idea is that the air lock from time to time triggers a high temp signal which makes the engine run on low rev /emergency mode only? No overheat alarm is heard from the controller but it might be broken.
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    Johnson 70 hp 3 cyl / 2-stroke dies when giving more throttle

    Thanks. You are right, the spitting stops when throttle opens a bit. And we did check the reed valves and they are in good shape. So I don´t think the spitting is releated to the hesitation/loss of power. About power, I had many engines of this power rating and on similar boats. Alltough I can´t...
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    Johnson 70 hp 3 cyl / 2-stroke dies when giving more throttle

    Thank you! Will investigate. The problem however occurs also with a cold engine, and comes and goes without any obvious link to temperature.
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    Johnson 70 hp 3 cyl / 2-stroke dies when giving more throttle

    Could be, but I,m hesitating since I´ve never done that on a motor like this and might cause further issues. As I asked above, how could my problems be intermittent if the cyliner/piston is dagamed? Sometimes it do not hesitate the same way, the boat accelerates well and the engine deliver good...
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    Johnson 70 hp 3 cyl / 2-stroke dies when giving more throttle

    Hello again folks, Unfortunately I still have this issue. We now did all ignition related tests specified in the service manual, and we are confident we have a good spark at all op conditions and that timing is correct. We are thus pretty sure it's fuel related. The service book does not...
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