'91 25 hp Jonny idles fine then dies

[fireman57]

Never had a moments trouble until now with my sweet little engine.<br /><br />Starts very hard. have to choke a lot. Used to start up second turn of the key with just a little choking. runs fine once it starts but will die after about 15 minutes idling. Then starts hard again. <br /><br />Cleaned and rebuilt carbs. Doesn't miss so it's not the powerpacks. Changed plugs. Did find small crack in fuel line which was fixed on the spot with a filet knife and screwdriver.<br /><br />There is only one adjustment screw on card and the automatic choke has the red handle on it for adjustment of I'm assuming low idle. I have this pushed all the way toward the powerhead to keep it running decent. Have my throttle cable adjustment at the engine turned up fairly high to keep it running. Tends to die also when trolling at very low speeds. I do a lot of striper fishing on the Ohio below the dams so it is important that engine keeps running so I don't get pulled into the gates.<br /><br />Have changed fuel.Would it be advisable to go to a better grade of two cycle like quicksilver? Have been running the cheap Walmart super tech with no apparent problems until maybe now.<br /><br />Thanks guys, you are always good help.<br /><br />C'mon, as of Sept 8th someone should have figured this out. I'm still stumped.

 

[fireman57]

Re: '91 25 hp Jonny idles fine then dies

bump

 

[BF]

Re: '91 25 hp Jonny idles fine then dies

hmmm, well how is the primer bulb after it dies? Full of gas or do you need to pump it a few times to get the carb bowl full of fuel again? Maybe fuel pump is marginal at low rpm's (?), or it's sucking air in fuel line (a bit). My first thought was carb rebuild/dirty idle circuit in carb, but you've been there already. How is the water flow? Could it be overheating?<br /><br />Do you also run it at higher throttle sometimes (and works good?) or do you spend 99% of your time idling? Just wondering whether this only an idle problem, or if other symptoms would show up at other throttle settings. Have you decarb'd it lately?<br /><br />Anyway, not much help I know, but at least you have a response now!<br /><br />Brent

 

[fireman57]

Re: '91 25 hp Jonny idles fine then dies

The primer bulb is fine. Viagra fine. Water flow is like me at 5 a.m. I spend probably 75% of my time idling but run flat out like a banshee with no problem. Boat cruises about 25 mph which is fast enough for me in a 14ft john. I just wonder if the red lever on the choke is a low idle mixture adjustment and if it might be running a little lean. Engine never did smoke very much but now it isn't smoking at all.<br />By the way, thanks for the reply! I thought for a while there that I had bad breath.

 

[marinemech]

Re: '91 25 hp Jonny idles fine then dies

red lever is for manually priming (choking) engine if you had to pull start (dead battery etc.) there should be an adjustment screw on carb top turning screw in makes moter leaner (less fuel)turning screw out makes it richer (more fuel)<br />warm up moter than adjust screw 1/8 turn at a time allowing moter to respond at idle in gear not tied to a dock until you get the best idle out of moter

 

[fireman57]

Re: '91 25 hp Jonny idles fine then dies

Thanks marinemech for clearing up the red lever. I now have it all the way back toward the block which I assume is choking it. If that is the case then my problem was running lean. That is why the engine would finally die and be tough to restart without choking. I will pull this lever back and do the adjustment with the screw. Thanks a lot.

 

[fireman57]

Re: '91 25 hp Jonny idles fine then dies

Finally found the problem! A tiny flap in the diaphram in the fuel pump. Couldn't see it unless you forced fuel through it. It would "reseat" itself perfectly so you couldn't tell it was ripped. I guess the best thing to do if you suspect the problem is the fuel pump then rebuild it. The kit is only 18.00 and change.