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93 Johnson Fast strike 150- runs great at first start up, then....

S

soonrfish

New member
When I put the boat in the water after pumping bulb , it starts and runs great for as long as I go out to a spot. If I stop and shut it off for a while to fish, it will start back up, but have a difficult time idling and will not accelerate and die if I try to. I go through this cycle of start up, idle, put into to slow gear, then die if I attempt to accelerate to quick. It will go at low throttle for a while. I can sometimes save it from dying if I put it back into neutral.
After about 5 minutes of this, it's as if it snaps out of it. You hear the motor suddenly begin to idle and run correctly and then it is off as if nothing was ever wrong. Yesterday, I primed the bulb before we took off after fishing to see if that would help, but it did not, same issue. It was 95 at the lake yesterday, but it does this and seems like it needs to "warm up." Could it be from sitting in the heat? It doesn't need to " warm up" after initial start of the day from trailer though.
Puzzling and difficult to change fishing spots. Feels like an engine struggling under a load or an engine not getting enough fuel. Puzzling that it will do this and then snap out of it and run great after a short time.
I'm all ears if anyone has an idea.
Thanks
 
Does it smoke excessively on start up? Are you pumping primer bulb pri to cranking? When was engine last serviced? P!ease post compression numbers.
 
Doesnt smoke much at start up. I pump primer bulb on initial start. Tried doing it after sitting out fishing, same problem. Hasn't been serviced this season. (If you mean plugs, carbs) Dont currently have compression numbers, should it be around 110-115?
 
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1.Doesnt smoke much at start up. Dont consider it excessive
2.I pump primer bulb on every initial start. Tried doing it after sitting out fishing, same problem. 3. Hasn't been serviced this season. I do it in the fall before storage(If you mean plugs, carbs)

Dont currently have compression numbers, should it be around 110-115?
 
What happens if you bump the choke when it wants to stumble? While your fishing,is motor tilted up? My first feeling is fuel heat soak,thats why so many questions!
 
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My brother had an outboard (mercury, not Johnson) tha texhibited similsar symptoms. Would start and run great first thing. Get to a fishing spot and fish for a while, and it wouldn't start or was very hard to start. If he could get it going it would "clear up".
In his case, it turned out that there was a very small crack in the water jacket (or block? It's been a long time) that didn't leak when it was cold, but after it warmed up it would let a miniscule amount of water into cylinder.
 
Gas is fresh. Oldest gas in take would have been from first time out in April.
Last time out was the first time I tried bumping the choke while it did this, but I'm not sure it made a difference. It didnt do it as long as usual, so maybe it did help. Motor was left down the whole time.
It is not difficult to start after sitting. It just Boggs and wont stay running.

I could pull kids around in a tube all day with no problems as long as I dont stop for a long amount of time. That's what's weird.

Fuel heat soak hmm.....
 
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