Johnson Javelin 85 HP Stalls out

[tnglc26]

We have a 1976 Johnson Javelin 85 HP Model number 85 ETLR76G. The problem we are having is it stalls out in forward or reverse gear when the throtle is past half open.<br />We ran it on the trailer and it does fine at WOT in both forward and reverse. When we put it in the water it seems to have trouble idling, but once it idles fine and we try to pull out it seems to run great until half throttle, then it bogs down and stalls out.<br />The plugs are new, gapped at .030, and all are firing as should.<br />The gas line, bulb, and tank are all also new.<br />Gasil is being mixed 50:1<br />We have pulled the carbs off and cleaned them as good as possible (looks like new casting).<br />We also replaced the gas lines to each carb.<br />The only thing we noticed is there are two different jet sizes.<br />We think maybe the problem lies there.<br />Is it common to have the two different jet sizes, and if so where do the larger jets go as opposed to the smaller ones?<br />Any other suggestions that may help this problem?

 

[McGR]

Re: Johnson Javelin 85 HP Stalls out

It certainly sounds like there is a problem with the high speed fuel circuit... I believe you're probably "barking up the right tree". An unloaded motor (on trailer) and a loaded motor (in water) typically behave very differently due to load and exhaust back pressure, so the fact that you can goose it unloaded means little. BTW, it's not recommended to exceed about 2000 RPM unloaded... can damage the motor etc. Regarding, the jet sizes... it's not terribly uncommon to have different size jets. Different jets are often used to compensate for thermal differences inherent to various cylinders on a motor. You really need to check a parts manual to be sure. One other note... Did you pull both the high speed and low speed jets when cleaning the carbs? The high speed jets (the ones you probably should be concerned about) are located behind the fuel drain screws. Another thing worth checking is the fuel pump, you may want to have someone pump the bulb manually while you accelerate to see if this makes any difference.

 

[tnglc26]

Re: Johnson Javelin 85 HP Stalls out

Pumping the bulb while loaded does not make a difference, we did try that the first day out on the water. After that we took the cover off the carbs and repeated the same processes as before looking at the amount of gas each barrel was releasing. Each barrel seemed to be releasing the right amount with the exception of the lower left, which the first cleaning of the carb solved that problem as today they all four were almost identical in amounts, but the initial problem-the stalling-remains the same. thanks.

 

[tnglc26]

Re: Johnson Javelin 85 HP Stalls out

Well, we pulled the carbs back off and cleaned them again paying special attention to the high speed jets. Took her to the water and it ran great. Also, I talked to a guy local who does marine repair and he said having two different size jets is normal also but the placement should be on corresponding sides (ie two small on the right, and two large on the left or the other wway around). Is this true?