1999 40 hp Johnson fuel problem...

[DVTO2]

I have a 1999 40 hp, oil injected 2 stroke, Model J40PLEEA, serial # 0 04616714. This is the oil injection motor.

The motor starts easily and will idle at the start. It runs full out with no problem. I can get 25 mph in my Lund Alaskan SSV 18 with 4 adults in the boat. However, when I am in a fishing situation, where I am trolling around at slow speeds, putting it into neutral, trolling again, it has a tendency to die out on me. I know it could come down to some kind of leak in the fuel line, but I have put in new lines form the tank and new gaskets on the fuel tank. Suggestions about how to further trouble shoot this? I have not taken the fuel pump apart to change the gasket and I have no idea when this was last done.

 

[racerone]

Compression test first.

 

[oldboat1]

in-line fuel filter replacement?

 

[DVTO2]

I replaced the fuel filter and still have the problem.

 

[oldboat1]

Rule out low compression, then think carb issue. (Also might simply need to increase throttle idle adjustment.)

 

[DVTO2]

So I got 125 PSI on both cylinders with my 40 year Hawk compression tester that I am amazed I still have (or even knew where to find it).

 

[DVTO2]

It idles fine sitting still, but in a fishing situation, (slow troll, neutral, reverse, slow forward), I had trouble with it cutting out last year, very aggravating. I could try increasing the idle but I think there could be something else going on.

 

[oldboat1]

Shouldn't be jarring and jolting when you snap it into gear, but on the other hand the standard 750 rpm in gear might seem like a fairly fast idle. If you flush on muffs, it will be around 1000 rpm.

 

[DVTO2]

My idle screw was a half turn from being too lean. It takes about two whole revolutions to get it to being too rich, so i opened it a half turn and will test that on the water.

 

[oldboat1]

Hmmm. That about 1 1/2 turns open? Sounds close to being on target.

 

[DVTO2]

My water test was not a success. The motor still starts easily and runs beautifully at wide open throttle, but died at slow trolling. I brought it home started over on the idle mixture screw, settling on 1 1/2 turns open (as suggested) and increased the idle rpm adjustment. I don't have a tach on this motor to read the RPM, but I have run outboards my whole life and can guestimate what sounds good. I'll do another water test tomorrow, and play with the adjustments while I'm on the water.

 

[DVTO2]

[No message]

 

[DVTO2]

I tried adjusting this but it didn't move the idle speed up high enough.

 

[DVTO2]

Then i adjusted this.

 

[DVTO2]

I also opened up the idle mixture another 1/2 turn, to 2 full turns. I did all this tinkering on the water. Engine now trolls and reverses really well, and is not too high when in neutral.

 

[oldboat1]

Glad you found a way. Catch some fish!