spudzone
ArboristSite Member
Hello all,
I recently did a complete rebuild on a 5105 with a scored piston and sloppy crank bearings. Everything went well including a touch of mild port work & MM but no carb or intake work yet. For post-build testing and tuning, it started easily on second pull, but the tune was nervous and wouldn't settle down or respond well to adjustments. I shut it all down after a minute or so to look for obvious leaks and clean up the carb. The carb seemed pretty clean but I went through it and put a kit in regardless. Feeling quite confident for an easy tune & test after careful intake reassembly, no start. ZIP, NADA - just like I never put fuel in it. Double checked everything I could - coil tested fine, good impulse connection, good intake manifold lock-down, carb air-tight, diaphragm placements correct, vac and pressure tests all pass. I even replaced the intake & impulse parts for fear of a tear, new fuel line, etc, etc. I even pulled the carb apart and did an hour of high-temp ultrasonic bath.
Importantly, it will run on a few CCs of fuel injected into the carb throat for several seconds, but once that's consumed, it's done. Plug never looks wet as in a flooding scenario. I thought the short run would kick-start fuel flow, but I'm not seeing that.
Is it just time to get another carb?
I am totally stumped. After a couple dozen mostly easy builds, this one has broken me! Help, please.
Thanks, Chris
I recently did a complete rebuild on a 5105 with a scored piston and sloppy crank bearings. Everything went well including a touch of mild port work & MM but no carb or intake work yet. For post-build testing and tuning, it started easily on second pull, but the tune was nervous and wouldn't settle down or respond well to adjustments. I shut it all down after a minute or so to look for obvious leaks and clean up the carb. The carb seemed pretty clean but I went through it and put a kit in regardless. Feeling quite confident for an easy tune & test after careful intake reassembly, no start. ZIP, NADA - just like I never put fuel in it. Double checked everything I could - coil tested fine, good impulse connection, good intake manifold lock-down, carb air-tight, diaphragm placements correct, vac and pressure tests all pass. I even replaced the intake & impulse parts for fear of a tear, new fuel line, etc, etc. I even pulled the carb apart and did an hour of high-temp ultrasonic bath.
Importantly, it will run on a few CCs of fuel injected into the carb throat for several seconds, but once that's consumed, it's done. Plug never looks wet as in a flooding scenario. I thought the short run would kick-start fuel flow, but I'm not seeing that.
Is it just time to get another carb?
I am totally stumped. After a couple dozen mostly easy builds, this one has broken me! Help, please.
Thanks, Chris
