94 Johnson 50 hp J50TLERE Carb Questions

[steamin53]

I've had some long term idle issues with this engine and undertook today to clean and "rebuild" the carbs. The engine has run great at high speed. These are very simple carbs and actually about the only thing in the kits that could be changed was the needle valve and seat, and the gaskets. The carbs looked actually quite clean (I've seen much worse carbs run pretty well). I did not remove the welch plug as those circuits seemed to be clean and passed carb cleaner and air quite well.

I replaced the two fuel lines from the pump to the carbs with 5/16" fuel and emission hose and a coulple of questionable hose clamps (wire ties).

Ok here's the questions.

1. Prior to this work the slow speed air adjustment was best at around 2 turns out from the needle seat. Now it's around 1 turn out top carb and not very responsive to adjustment there at all. The bottom carb is best at around 3/4 turn out. Given that I only changed the float needle and seat and the gaskets, I'm puzzled at the change in the adjustment for idle AND ESPECIALLY AT THE NON-RESPONSIVENESS of the top carb. Any ideas?

2. Also, is it possible to get free from the VRO fuel pump and go to premix using the old style diaphram fuel pump? I've had OMC 50 hp engines in the past and they were terrific for idle...but not this one!

3. There's a hose nipple on the bottom rear of the air silencer which I assume is for a hose to drain off fuel/oil spillage from the carb throats when tilted. Where's the hose go? I assumed it to go to the nipple on the bottom front of the intake manifold. Is that correct?

Steve

 

[multimech]

Re: 94 Johnson 50 hp J50TLERE Carb Questions

If it is non responsive to adjustment, that means it is clogged up. You should be able to turn it from its initial settings, down to no turns and have that cylinder drop off. It should pick back up near it's initial adjustment. Are you sure these carbs are clean? Carbs are clean or not clean. There is no "compared to" in carbs.

 

[steamin53]

Re: 94 Johnson 50 hp J50TLERE Carb Questions

Actually there is one other possibility besides the carb being dirty. If one crimps the fuel feed to the primer the carbs get little to no idle fuel.

I had removed the starter for better access to the bottom carb and on reinstallation had captured the fuel feed to the primer between the starter and the crankcase....dumb. I found it when I tried to test the primer at 2K rpm and nothing happened...(it's supposed to drop the rpm at least 1K). Good daylight sure helped too.

These carbs seem to get their idle fuel through the cover on the top of the carb and draw it through three tiny holes doen into the carb throat. The mixture screw and a brass air port are also in the cover. The cover connects directly to the primer solenoid assembly.

Oh well... anything can happen. I'm sure glad I didn't take my first course today which would have been to remove the carbs and check my work perhaps also cleaning beneath the welch plug. The bottom carb on this thing is really a pain to get off because of the VRO pump.

What baffled me was that I have built over 100 carbs ranging from trips on sports cars to the garden tiller and points between. I was certain I had done it right. Just goes to show it's the little things that gitcha!

Almost done. Now to take it to the water to finish adjustment and test it.

Steve