91Johnson 15 hp

[CER79]

Recently I have been having trouble with this motor bogging down at low speeds to the point where it will stall when I try to accelerate . It will also stall in neutral sometimes and when trying to shift from neutral to into gear . The only way i can keep it going is to pull the choke in and out a few times as I throttle up. It runs fine wide open and at midspeeds. This spring I put a carb kit in after it would not start and with a little help from this forum it has run fine all summer long up until this point. I am thinking it is a fuel supply problem but am confused as to why it would run fine at high speeds but not low. Checked plugs,tank vent, hose primer bulb and lines and all seem OK. Any thoughts or help appreciated before I start replacing stuff or put in another carb kit<br /><br />CER

 

[steamboatwilly]

Re: 91Johnson 15 hp

One suggestion would be,take carbs back apart and check low speed jets real close.

 

[OBJ]

Re: 91Johnson 15 hp

These carbs have that little idle lift tube in them if you recall. Remember how small the little tube holes are? Just a little bit of "stuff" will mess the idle up. I think I would pull the carb too and check the idle circuit out and make sure the tube passage is open.

 

[rgp]

Re: 91Johnson 15 hp

I had a similar problem with my 15HP 1990 Johnson shortly after I purchsed it (brand new). Returned it to the dealer and they did a no-charge warranty repair. When I inquired, the technition mentioned something about a little tube that came loose or disconnected or some such thing. They don't tell ya much (job security). The motor's run like a Swiss watch ever since then.

 

[CER79]

Re: 91Johnson 15 hp

Thanks to all, I do remember that little tube when I had it apart . I will pull the carb clean it and check it out and post results when done, thanks again.<br /><br />cer

 

[CER79]

Re: 91Johnson 15 hp

Took carb off and apart, checked idle pick up tube and that looked fine, blew out all the little ports with compressed air and ran a very fine wire through them, reassembled and Just got off the water with the same results. Also tried adjusting the low speed and that made no difference. It will idle but will still bog out when shifting from N to F unless I pull the choke in and out a few times to keep to keep it running while I throttle up. Runs fine wide open and midspeeds. Still think it is a gas problem because of the ability to keep it going with the choke. Did I miss something ? As always any thoughts or comments are appreciated!<br />cer

 

[steamboatwilly]

Re: 91Johnson 15 hp

Are you letting it warm up before you throttle up?

 

[CER79]

Re: 91Johnson 15 hp

James, she is up to temp, spun it around the river for 1/2 hour.<br />CER79

 

[steamboatwilly]

Re: 91Johnson 15 hp

I think you have an air leak somewhere on the carb.or theres something still stopped inside.What about gasket between carb. and manifold.Maybe the idle time.

 

[OBJ]

Re: 91Johnson 15 hp

Couple things to look at Cer....<br /><br />Check the cam roller and lever, make sure the roller doesn't have a large groove wore in it and the lever isn't broke. Look at the cam that the roller rolls on. Make sure that when the cam reference mark is touching the roller at center, the throttle plate is just starting to open.<br /><br />Check the carb cover, that's the black plastic piece on top of the carb. Inspect it for cracks from over tightening the retainer screws.<br /><br />How far open is the low speed needle?<br /><br />If you can fit a clear piece of plastic line between the carb and fuel pump, look for air bubbles.<br /><br />Check the primer solenoid red lever. Make sure it hasn't gotten turned. It should be pointing to the rear of the solenoid. Look at the solenoid cover on the front of the solenoid where the hoses connect. Make sure it isn't cracked and there is no gas leaking out the red lever where it goes in to the solenoid cover.

 

[CER79]

Re: 91Johnson 15 hp

James OBJ,<br />Thanks for both of your replies, the gasket between the carb and manifold looks OK. The plastic piece on top of the carb does have a crack but that has been there for a long time perhaps that has become worse. I will double check on that and replace it if I can find one . Low speed needle about 2 1/4 turns. I tried all kinds of settings to see if it would make a difference but it did not. I will check on your other suggestions and repost. Thank you both once again.<br />cer

 

[MCM]

Re: 91Johnson 15 hp

CER,<br /><br />2 1/4 turns on the low speed needle doesn't sound right, I don't have a manual for your motor, do you?<br /><br />I could be wrong but I think the initial setting should be 1 1/2 turns, At 2 1/4 you may be creating a flooding situation.<br /><br />Do a search for Joe Reeves post on initial slow speed needle settings.<br /><br />Actually I've got it right here<br /><br /> http://www.iboats.com/cgi-bin/ubb/ultimatebb.cgi?ubb=get_topic;f=28;t=036900#000004 <br /><br />Good Luck,<br />Mike

 

[itstippy]

Re: 91Johnson 15 hp

"Low speed needle about 2 1/4 turns. I tried all kinds of settings to see if it would make a difference but it did not."<br /><br />The setting of the low speed needle makes no difference at all? All the way in, 2 1/4 out, in-between, makes no difference?

 

[CER79]

Re: 91Johnson 15 hp

Sorry a little history and clarifcation are in order. MCM ,earlier this spring motor wouldn't start put new carb kit in and did adjust it to 1 1/2 turns could not keep it going at that adjustment was advised by a forum member here to back it out another turn and that fixed it and it has run great all summmer till now. Itstippy,"Low speed needle about 2 1/4 turns. I tried all kinds of settings to see if it would make a difference but it did not." What I meant is it did not help the bogging out problem I am having but it did affect the running at idle and starting. Sorry for the confusion. Any input is very much appreciated thanks.<br />cer