150 johnson wont start when hot

hartwell

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Sep 7, 2001
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i have a 1996 150 johnson that wont start when hot, it sounds strange like it has no compression,but when it cools off it is fine,it runs just fine,any suggestions?
 

chasem

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Aug 20, 2001
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Re: 150 johnson wont start when hot

hi hartwell i have a 1979 55hp evinrude with the same problem. Is your starter extremely<br />hot . my gets hot and after it cools down it will fire and run good. It just gets so hot <br />i cant figure out what is the problem. I think with mine the heat causes the copper <br />in the starter to expand and when it cools it contracts back to gether and will start
 

JB

Honorary Moderator Emeritus
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Mar 25, 2001
Messages
45,907
Re: 150 johnson wont start when hot

Howdy, Hartwell. One of the things that interferes with restarting the engine shortly after being shut down is poor tank venting. Try cracking your tank cap and/or pumping your primer bulb before you try her out.<br /><br />Another possibility is operator error. Do you choke/prime it when trying to restart when hot? Don't, you may be flooding it.<br /><br />Good luck.<br />Red sky at night. . .<br />JB :)
 

hartwell

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Sep 7, 2001
Messages
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Re: 150 johnson wont start when hot

chasem: i dont think my problem is with the starter,it dont get hot or drag, your problem definitly sounds like starter but thanks anyway
 

hartwell

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Sep 7, 2001
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Re: 150 johnson wont start when hot

j.b. cornwell: my engine soundslike it dont have compression when trying to start it, but i will try what you said, thanks
 

Backlash

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May 16, 2001
Messages
586
Re: 150 johnson wont start when hot

Hey Hartwell, Just to clarify, when you say "it sounds like it doesn't have compression" do you mean your engine turns over faster than normal? :confused: Have you run a compression check?<br />Backlash
 

hartwell

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Sep 7, 2001
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Re: 150 johnson wont start when hot

sounds like it is turning over fast like it has a compression release or something just sounds strange and i cant describe the sound, compression is good
 

hartwell

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Sep 7, 2001
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Re: 150 johnson wont start when hot

am i answering these questions in the right manner im new aT this and not sure im doing it right
 

Backlash

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May 16, 2001
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586
Re: 150 johnson wont start when hot

Hey Hartwell, That answered my question.......I'm at a loss to answer yours though :( . I've never come across anything quite like the symptoms you're describing & I'll be very interested to hear what's causing it. Please keep us posted. In the meantime, let me ask one more question. When you say the engine is hot, do you mean HOT as in overheated? <br />Backlash
 

hartwell

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Sep 7, 2001
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Re: 150 johnson wont start when hot

no not overheating, just through normal use, ive talked to boat mechanic friends and they dont know either, but they all specialize in merc.
 

gregga2000

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Sep 3, 2001
Messages
5
Re: 150 johnson wont start when hot

are you getting spark when it does this could be your ignition power pack a friend had the same problem he had twin outboards so he tried the power pack from his other engine it solved his problem
 

hartwell

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Sep 7, 2001
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Re: 150 johnson wont start when hot

gregga: im not sure, but once it cools off and starts it will run perfect all day if you dont shut it off
 

byordy

Petty Officer 2nd Class
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Aug 13, 2001
Messages
114
Re: 150 johnson wont start when hot

Hi hartwell,<br />Is it possible that the starter bendix is not engaging? The starter motor would spin rapidly and make a stange noise that could sound like the motor is turning with no compression. The motor would not be turning over however. After the motor cools off the bendix could work freely again.<br />To check this out pull the motor cover when the motor is acting up and see if the bendix is actually engaging the flywheel and turning the motor.<br />To lubricate the bendix if this is the problem use a light silcon type lubricant that won't attract dirt. <br />Good Luck,<br />Bill.........
 

hartwell

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Sep 7, 2001
Messages
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Re: 150 johnson wont start when hot

byordy: the bendix on this motor is not out in the open but it is very possible that this is the problem , ill check it out, thanks\
 

Beernutz

Petty Officer 1st Class
Joined
Aug 14, 2001
Messages
287
Re: 150 johnson wont start when hot

As Gregga suggested, you need to check to see if you're getting spark while it refuses to start. Electronic parts can become intermittent when overheated.<br /><br />When you shut an engine off, cooling water stops circulating, and you can actually experience a temperature spike for a period of time following shut-down. This is more of a problem when the water pump is worn, and normal cooling is compromised to begin with. Have you replaced the pump recently?<br /><br />You should have an optical ignition system. The possibilities are numerous, and would require a complete diagnostics test, most likely while it's in a failure mode.<br /><br />I have an '01 150 Johnson, and it always cranks like it has no compression, but runs perfectly. Guess that's the nature of the beast.<br /><br />Good luck!
 

clanton

Rear Admiral
Joined
Jul 9, 2001
Messages
4,876
Re: 150 johnson wont start when hot

Check, sensor, power pack, and coils. Could be a Quick Start problem. Rpms should go to 1100 rpms for 5 seconds on hot restart. Cold start should hold 1100 rpm until engine warm. The Quick Start is in the power pack. last thing to check is pump inside vapor septerator.
 

sony2001

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Mar 17, 2001
Messages
607
Re: 150 johnson wont start when hot

When the engine is hot have you tried maximum throttle in neutral before you crank the engine? No choke.
 

hartwell

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Sep 7, 2001
Messages
13
Re: 150 johnson wont start when hot

thank you for all your answers and ill check them out soon and let you guys know what i found. i do think it is some kind of sensor.
 

clanton

Rear Admiral
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Jul 9, 2001
Messages
4,876
Re: 150 johnson wont start when hot

Look for arcing from coil to metal plate between coil and power pack.
 
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