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2003 150 Johnson wont idle

F

fishcrazy

New member
when cold or hot it doesnt see

when cold or hot it doesnt seem to matter the idle is the same. It will not stay running in neutral and the choke doesnt seem to help any. There is a fair amount of exhaust fumes it seems but I dont know if that is unusual. If you try to put the motor into gear it wants to cut off and the throttle up must be done very fast to get the motor to accelerate and not cut off. Once you get the motor to accelerate the motor runs great and is smooth and strong. No problems at all at speed. Just problems idleing in neutral and in gear. It seems that you have to push the throtle a long ways forward before you get any reaction from it at all. Is that normal? This is a 2003 boat that I recently bought. Some have told me to decarb the motor but dont know how to do that. Any advice or pointers would be appreciated.
 
A carburetter clean rather tha

A carburetter clean rather than decarbonising the engine I would think.

Instructions for decarbing the engine with Seafoam are on the can or Seafoam's website if you want to try it
 
So what is the difference in t

So what is the difference in the carb cleaning and the decarbing process. Dont you dump it through the carb when you decarb with seafoam? I would have thought that would clean it all. What am I missing here.
 
To properly clean a carb you h

To properly clean a carb you have to dismantle it and clean all the jets and passages.
 
What I had intended to try fir

What I had intended to try first is to pre mix 3/4 gal of gas and 16 oz seafoam and some oil and run the mix through the engine by connecting to the fuel line port where gas normally goes into the primer bulb. Let the mixture sit in the motor for 15 minutes and run it again and repeat if necessary. I would think that there would be some hope of cleaning the carbs this way. Thought this would be easy to try before pulling anything apart. What do you think?
 
"Well its gonna depend on how

"Well its gonna depend on how bad your carburetors actually are. And you can't find out unless you take them apart, clean if need be and rebuild if need be. However, its your money and your time thats at stake. If you feel that running sea foam or another good carb cleaner thru it will make it run better than go with it. You never know unless you try it. Hope this helps!!!"
 
"decarbing,...came along,about

"decarbing,...came along,about 15 yrs ago....it is a def good thing to do,....however,...decarbing is a maintainence issue,or treatment,..it can and does affect the idling,of a bad carboned engine..however,...most any prob,....is NOT related to,and decarb will not cure most eng prob's."
 
jwbmarine I appreciate the hel

jwbmarine I appreciate the help. I agree with you. Im hoping that I get lucky with the decarb procedure and clean up something that is blocking the fuel flow on the idle side. If that doesnt help the situation I then need to start looking for other causes. This motor will idle but it is somewhat rough and uncertain. It doesnt want to transition to accelerating it seems is the main issue. It tends to want to cut off when you drop it into gear and try to throttle up. It will idle in gear most of the time but its when you try to throttle up that it cuts off. Is that is symptomatic of anything. Just the fact that it will sit and idle in neutral sort of ok or in gear but wants to die when throttle is increased sounds like it should point to something. I just dont know what but I feel that someone with some outboard knowledge might have a clue where to start looking. Thanks for any opinions.
 
"Double check the shift switch

"Double check the shift switch on the shift lever. If that is sticking, engine may cut off like you describes.
Test by disconnecting it, bit note that engine may be hard getting out of gear.
Spray with WD 40 or similar to be sure it moves freely in the slide.
If you have to move the throttle lever a long distance before anything happens, re-adjust the throttle cable at the engine."
 
I will check that throttle cab

I will check that throttle cable adjustment. Not sure about the shift switch on the shift leaver just how to check it. Could you elaborate on what I am looking for there. I do know that when you put it into gear it makes a noise going in like a sort of grinding noise like the clutch on an old car not letting the gears engage without grinding a bit. Doesnt do that if you are more deliberate about putting it into gear. Dont know if that means anything but probably not.
 
"The switch cuts ignition puls

"The switch cuts ignition pulses when activated.If it gets 'hanging' and you try to give throttle, engine often stalls.
Just try to disconnect to eliminate."
 
I did some visual inspections

I did some visual inspections of the fuel delivery system yesterday and discovered that the primer ball outlet side toward the motor was leaking a bit when you pumped it up tight. I repositioned the clamp and tightened it up a bit till it didnt leak any more and cranked the engine in the yard on muffs on a garden hose and the thing seemed to idel ok and did not stall out as I gave it throttle. I havent tried it in the water under load but it appears that it made a difference. It wasnt leaking much at all and it seems hard to believe that this could have been the problem. Could someone with some more experience than I chime in here with an opinion on this. I intend to put the boat in the water real soon to check it out.
 
It seems that the fuel leak wa

It seems that the fuel leak was sucking air enough to make a big difference. I took the boat out to test it today and it ran great. Thanks for all the suggestions and help offered here. Much appreciated!
 
Well it is acting up again jus

Well it is acting up again just like it did before. Dont understand how it went from running perfect to idling rough again and hardly staying running at all. I wonder if I should suspect the fuel line and primer bulb or something else. Any thoughts?
 
"One thing I noticed in your p

"One thing I noticed in your posts is that you say it grinds a bit when shifted into gear.
You should shift from neutral into either gear with a quick deliberate process. Do not linger through the shifting process. It should clunk once when going into gear, and if you continue to "linger through the shift" you will tear up the clutch dog in the lower unit.

To elaborate on Morton's point, the shift switch is located when viewed from the starboard side, sort of low, below the level of the lowest carb, on the shift linkage. There is a two-wire braided sleeve harness that runs up to the powerpack area. On the shop.evinrude.com site pages for your motor, in the cylinder and crankcase section, it is item number 72 on the drawings. That is the harness he wants you to unplug to test to see if the switch is stuck. If the motor performance radically improves with the switch unplugged, you may have found the problem."
 
Thanks for the explaination. T

Thanks for the explaination. That seems easy enough to check. I guess if it is sticking sometimes and sometimes not that could explain it running so good the other day and not so good a few days later. I will check that out. Thanks.
 
"10-4.
A bit more....the sh

"10-4.
A bit more....the shift switch momentarily kills 3 cylinders during the shifting action, to ease the loads and forces on the L/U.
So, if it is stuck closed, you will be idling on three cyls, and when put into gear, will almost surely stall.
This is kinda unlikely...but likely enough for you to test, and it is a free test!
It wouldn't be the first stuck shift switch....

You have optical ignition, which is tricky.
I still lean toward dirty carbs though.

Be sure to follow up with the fix, or continued repair attempts. We who follow these threads appreciate a resolution."
 
"look at ol doug go.......what

"look at ol doug go.......what r u doing man?...studing outboard books 24/7..........................well,..i used to myself...cvr to cvr...."
 
Well I took the time to pull t

Well I took the time to pull the plugs to check them and found no reason to be concerned there as they all looked normal and almost new as far as I could tell. I did notice that there was no clamp on one of the lines that comes off the bottom of the OMV pump assembly at the motor connection point. I believe that this is the pulse hose. I dont know if this could be causing my problems but I assume there should be a clamp on the line right?
 
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