97 150 Looper Fuel Spit-Back

[ToddW.]

Hi everyone,
I am working on a Johnson 150 (J150NXEUC) that I re-built a couple of years ago and am still in break in. The problem I can't seem to fix is fuel spitting out of the #1 carb throat.

I decided to pull the carbs and manifolds again and examine them for mistakes or defects and while it was apart, I decided to replace the manifolds, gaskets and the number 1 reed valve cluster (even though the existing one didn't seem bad). At this point I am just trying to eliminate possibilities and the troubleshooting section of my OEM service manual only mentions reed valves and associated parts as a possible cause for fuel spit-back. I just tried to run it on a flushing device and even though it didn't start yet, when I stopped cranking, fuel spit out of the #1 carb!

Having read a little about vapor pump troubles I disconnected the hose from the pump to the #1 carb. Then when I cranked it, no fuel spit from the carb OR the vapor hose. When I reconnected the vapor hose and cranked the engine, it spit back again! Am I looking at a possible vapor pump diaphragm leak? Can anyone think of something else I should try? Thanks for any help you can give.

 

[Faztbullet]

Vapor pump is not connected to carbs

 

[jimmbo]

Is it Actually Spitting, or just dribbling out the Throat?

If you really Want to "Eliminate Possibilities" just replace the Engine with a brand New One

 

[ToddW.]

Thanks to both of you, I think I found the trouble. Hose from the Tee (vapor pump and main bearing vent I connected to the #1 carb vent instead of inserting it in the upper hole of the air silencer. I am surprised they used a hole in the air silencer for that hose to go into instead of a nipple like a hose usually attaches to. My bad mistake though. Don't do that!
I am now leaving for a few weeks and won't be able to test run my engine until probably Sept., but I appreciate the response that made me doubt myself and double check my connections. Maybe I can put this saga behind me.