98 johnson 4stroke carb

[boatman71]

any one w/experience with idle circuit,my carb has no idle mixture needle,needle end has been machined smooth.only idles w/choke butterfly partially adjusted closed. thanks

 

[OBJ]

Re: 98 johnson 4stroke carb

Morning boatman...<br /><br />What horsepower is your 4 stroke.

 

[boatman71]

Re: 98 johnson 4stroke carb

thanks for reply OBJ,my eng is model#j15frec,hence 15hp,also have service manual for E/J 5 thru 15 four stroke in hand. engine will not idle down w/adjustment,dies out.initial run had no WOT,cleaned, rebuilt carb,did not remove welch plug in bottom of float bowl.rebuilt fuel pump.now have WOT, interesting to find idle mix screw machined down smooth,needle part in carb smoothed in also.did omc make an emission change? thanks again

 

[OBJ]

Re: 98 johnson 4stroke carb

Hi boatman....<br /><br />Did ya' follow the tuning instructions in the service manual....to the letter? Apparently, you did some good with the carb rebuild now that WOT is there again. Not knowing how long the engine set before you got it or this is a problem that just cropped up, removing the welch plug would have been a good move. They aren't hard to remove or to put a new one in. Trying to recall the initial needle adjustment and I want to say about three turns out from gently seated. This sound about right? Final adjustment made with the engine warm and in gear. Idle adjust is made with the idle adjustment screw on the motor side of the carb. You may want to check this adjustment screw. This screw basically holds the throttle plate a bit open.<br />The emissions change came from the EPA that said boaters maketh to much smoke and emission. This was the main catylist for all the new inovations in outboards we've seen over the past few years. The would have come anyway but the EPA just put it in high gear.<br />Post and let us know how yer makin out with the four stroke. Thanks.

 

[boatman71]

Re: 98 johnson 4stroke carb

thanks again,OBJ,going by the manual,notated idle mixture screw is a needle valve.mine is not.machined end smooth,or blunted smooth.so is area in top of idle circuit. eng sat from 2000 on,ran in backyard W/water perfectly twice per month.ran gas out ea time.having to choke at least three qtrs to keep engine idling fast,adjusted adjustment idle screw ,cant idle down. maybe welch plug on bottom or smaller one on side needs removal to clean.kit came w/larger welch plug.have a quote on new carb $410 to $450 so far,they love this one.thanks again.

 

[boatman71]

Re: 98 johnson 4stroke carb

had to have strong drink after quotes on carb emailed in,still wondering if my carb was an immaculate conception?

 

[boatman71]

Re: 98 johnson 4stroke carb

98 johnson 4stroke carb,update,as suggested,removed both welch plugs,had larger on in rebuild kit,have to buy the side smaller plug,ran fish line thru all areas from plug,no restriction.soaking carb again,will air blow. still think someone screw idle mix screw off smooth, will advise later,thanks,OBJ-by the way a fellow jim here too.

 

[boatman71]

Re: 98 johnson 4stroke carb

4stroke carb update,no improvement after reassembled,runs good mid rpm,will not idle down some unless choke is engaged. called dealership,tech said they capped off some of the 15hp 4stroke carbs. tech said to enlarge holes in on top in idle circuit some,did so.no change,will not idle,think its new carb time? $450 for a carb.my engine must be worth $25000!

 

[JB]

Re: 98 johnson 4stroke carb

^

 

[boatman71]

Re: 98 johnson 4stroke carb

thanks jb,yes have service manual,does carb have or motor have a vacuum source besides the intake? crankcase rubber hose to carb air horn pushing air pressure. will keep fidling with carb float settings. will advise,idle circuit is the problem i surmise.dont like have to choke to keep running. thanks