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87/88 175hp vro Johnson stalling/ flat spot .

S

Stephen 175

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Hi all, 87/88 Johnson VRO is stalling / flat spot at about 2000 revs. More times it dies but when it gets over flat spot will runs fine to 5600 rpm and back to 3000 rpm no problem no alarms.
 
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Yes 6 mths covid lock down. Put new fuel plugs nice colour. Perceived running around for 20 mins at over 3000 rpm went good. But each time it would take up to 5 times to get it over the flat spot. Sometime not starting at all.
 
Yes 6 mths covid lock down. Put new fuel plugs nice colour. Proceed to running around for 20 mins at over 3000 rpm went good 3 times. But each time it would take up to 5 times to get it over the flat spot. Sometime not starting at all.
 
Throttle open is if it's in the water....otherwise it can actually draw from exhaust side. I like to have it warm, but cold test will give similar numbers. Did it have fresh fuel when stored, were carbs run dry? Did it have ethanol fuel in it? So it ran fine when it was last used before standby?
 
timguy said:
Throttle open is if it's in the water....otherwise it can actually draw from exhaust side. I like to have it warm, but cold test will give similar numbers. Did it have fresh fuel when stored, were carbs run dry? Did it have ethanol fuel in it? So it ran fine when it was last used before standby?
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Tim will do compression test tomorrow . Yes new fuel new fuel tank fitted 91 octane gasoline 50-1 mix. It does not have oil injection any longer.
No engine was not ran dry last time 6 months ago it ran fine 6 months ago. It has starting up problem but does start eventually.When it does start it will idle. But flat spots or dies around 2000 revs . If it gets over 2000 it will run at 3000 /4000/ 5000/5500 and everything between and back down to idle. I did this 3 times out on the water for 20 minutes each time 1 hours running all up no cough or missing at revs.
 
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Load test battery even if new.------The starters can not tolerate excessive cranking.-----Take it apart for inspection and ohm test .---Perhaps new brushes.----You are pushing the key in while cranking it over for cold starting ?
 
No more than 15 percent difference between cylinders and preferably 10 percent. These usually run 95 to 105 psi, but I've had some decent motors at around 85 to 90. Head gaskets might be the problem. Could be deteriorating.....cause for worsening symptoms. These weren't real high compression motors. That 75 psi, then 80 and 82 are falling below MY standards....might wait for more advice from others on this motor.
 
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Bring it over ----I think I can trouble shoot your motor.----You have to do the inspection trouble shooting on your motor.----Perhaps invest in a factory service manual.
 
That's a bit of a drive. Might have to do this over the phone. Are head gaskets available there for a reasonable price? I've been to Australia....got friends there near Mackay. Really love Queensland. Probably getting late there now, eh? The summers there are hot, so went in the spring. (Oct)
 
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Yes it's a bit of a drive . Yer been to QLD my self a few times see friends and few fishing trips. Will order gaskets this morning have them tomorrow.
 
We take for granted sometimes our ease of parts finding and reasonable prices here in US and Canada. I am in northern Minnesota....a sweet spot for beauty freshwater parts.
 
Yes sounds like a peace of heaven. And yes if you could private message me your contact details. Do you have a Facebook. I would be able to video call you via messenger.
 
Hi took heads off found 2 bores scored on left bank 2 on right side 1 heavily. 4 piston have the edges burnt to about 1/8 radius from lean out at some stage. Not good at all. I also removed the carburettors and cleaned them out. It start ideals but start to die down the fule bulb goes soft. pump the fuel bulb up it ideals nicely again. Will have to change the bulb and put boat in water to see if it flat spots and Careys on.
 
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