1988 Johnson 15hp no idle

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Busbey

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only way to get it started is to spray starter fluid in the carb, full choke and 60% throttle. from there it sounds fine but will die and need to repeat previous steps to start bad up. also, we are not too sure how to adjust the low speed knob. how many 1/2 turns or full turns out from completely shut/tight until it reaches the proper point where you have that fine adjustment?

i know this is sort of a half arse explanation of whats going on but im sure someone out there can help me out.
 
Don't use starter fluid on a 2 stroke.Good way to ruin a good motor.

I believe the idle screw is 1 1/2 turns out.

Sure your fuel pump is pumping & is choke working?(butterfly closed)
 
Am suspecting the carb needs a good cleaning from the description but how about we start with a little more information such as how long has the engine sat without running? Is the fuel any good, does it have water in it, etc. Then we can give you a better answer rather that several guesses.
 
Rather than chance running the engine lean on fuel and oil, get a new kit and clean up the carb and install the new kit. That should solve your issue. Leaving an engine for a year, possibly with fuel in it, is not good with today's gasoline. And no, Seafoam will not clean it up without disassembly and proper cleaning. You can start your initial adjustment of the low speed needle at 1.5 turns and turn it in slowly until the engine speeds up and eventually lean spits then back it back out 1/4 turn and leave it. Thats a good ballpark adjustment.
 
here are 2 kits i found. would one be better than the other? $1 difference and around 15 bucks each.

Sierra
18-7223.jpg


Mallory
9-37101_0.jpg


but if all gaskets look good, could the problem be the jets just clogged? short of taking everything apart, is there any luck to be found with just soaking the carb? unfortunately i will not be the one doing this rebuild, a good friend is helping me. just want to make it as easy as possible for him. but if i need to do this, that it is what it is. im just looking for knowledge along with the best solution.
 
I would go with the Sierra kit, because it has everything the Mallory kit has plus it has the float needle clip, which helps prevent the float needle from getting stuck. I didn't see the float needle clip in the Mallory kit.


Pappy, is speaking the gospel here. Don't take short cuts when it comes to cleaning your carburetor, you will enjoy good running and low idling. I have a 1984 Evinrude 15hp and she runs great and idles wonderfully. So, you have a very well built motor and will give you years of good service if you treat her right. That starts with a good clean up with your carb.

Here is a link to a good set of articles related specifically to your motor. The author did a wonderful job of putting all that information together. It will help you maintain and even do some repairs if needed.

https://www.sschapterpsa.com/ramblings/OMC/OMC%20info.htm


Here is a link with a parts diagrams and you can order stuff from them as well.

https://www.marineengine.com/parts/johnson-evinrude-parts.php?year=1988&hp=15


Be careful, if you soak your carburetor. Remove all the plastic or rubber parts, the carburetor cleaner will dissolve and eat up plastic and rubber pieces. **Your carburetor may have a black plastic bowl type so, be very careful!!!***

Oh, by the way your fuel to oil ratio is 50:1 mixture. That is 16 ounce of TWC-3 marine 2cycle
oil to 6 gallons of fresh 87 octane unleaded fuel!!
 
ill go through this info you sent the links for. thanks a bunch.

quick question about the shaft length.. its a long shaft and looks to have been added on. i assume i will need about 200 bucks to turn this into a short shaft? whats the chances of me adding some sort of extension on my transom to add 5 inches? maybe a 4x4 and big c shaped aluminum piece over front and back of it? im sure there are many ideas and ways but if i end up needed a long shaft later on for a new boat, i dont want to have to make this change again.
 
There are transom jacks that can serve your purpose, without having to mess with converting to a short shaft. Pappy, would be a good resource to get some solid information regarding this matter.

Just make sure your anti-cavitation plate on your lower unit is about equal to or +/- an inch from the bottom of your boat/transom. You will get better performance that way.
 
All you need to make it a short shaft is a short drive shaft.The shift rod & water tube can be cut.

Short drive shafts by me run about $75.
 
which would be a better solution to my issue? how much is the plate? general balpark

when cutting the shift rob and water line, is this something a novice could do with general garage tools?
 
Busbey said:
which would be a better solution to my issue? how much is the plate? general balpark

when cutting the shift rob and water line, is this something a novice could do with general garage tools?

These are some considerations for jack plates. You maybe able to get a local machine shop or tech shop to fabricate one.(A Tech teaching shop may be able to make you a simple jack plate for a little more than the cost of the metal or supplies). My brother did that for his boat and motor. This way if you want to use it on other boat that requires a longer shaft you are good either way.

But if you wish to make it short shaft. Please be sure you have the correct measurements, of the water tube and the shaft rod. The water tube will have to be cut a certain angle at the very end. Also you will have to get a short drive shaft for the motor.


https://www.iboats.com/Outboard-Jack-Plates-Mounting-Brackets/dm/cart_id.421601306--session_id.442370411--view_id.217144

https://www.iboats.com/Adjustable-Outboard-Motor-Mounts/dm/cart_id.421601306--session_id.442370411--view_id.217143


Good luck
 
Thanks for the info. Still waiting on my buddy to take the carb apart and let me know what he thinks. Once I get it back home, I will start thinking about cutting or adding.. Still need to get this thing running first.
 
still waiting on my buddy to work on the motor. he was on vacation for a week.

as for the long shaft / short shaft issue, i found this.. https://www.basspro.com/webapp/wcs/stores/servlet/Product_10151_-1_10001_8782_225011002_225000000_225011000?cm_ven=bazaarvoice&cm_cat=RLP&cm_pla=8782&cm_ite=productname_link

i am still "if" about just ordering the drive shaft and cutting as suggested. if there is a tutorial or pics showing someone doing this, it would help my decision making. since i do not know how everything looks inside, i just cant make up my mind.

would someone happen to have some pics of this process?
 
Busbey said:
still waiting on my buddy to work on the motor. he was on vacation for a week.

as for the long shaft / short shaft issue, i found this.. https://www.basspro.com/webapp/wcs/stores/servlet/Product_10151_-1_10001_8782_225011002_225000000_225011000?cm_ven=bazaarvoice&cm_cat=RLP&cm_pla=8782&cm_ite=productname_link

i am still "if" about just ordering the drive shaft and cutting as suggested. if there is a tutorial or pics showing someone doing this, it would help my decision making. since i do not know how everything looks inside, i just cant make up my mind.

would someone happen to have some pics of this process?


I would go for the jack plate. Several members here have used them with success.
 
I found a much cheaper alternative. i think i may give it a go.... thoughts?

"""" The aluminum is 3/8" angle stock, the plywood is 2-3/4' pieces screwed/glued together. I need to drill the last 4 holes to attach the unit to the old transom. It seem sturdy enough to hold my 25Merc. ALL metal parts are either aluminum or stainless. """""""

https://forums.iboats.com/showthread.php?t=229049&page=1


Transommount003.jpg


Transommount001.jpg
 

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