717 backfire through carb

[tcapper]

Hi all,just joined the site, and decided to post because I am having a problem with my port side engine. I'll try to keep it short. Last year my boat was running great one weekend, the next , no port side engine.Started working on it and found that the accelerator pump was plugged, I cleaned the carb and got the pump to operate correctly. The problem now is that engine is backfiring through the carb.I know the timing,rotary valve,compression and all seals are good. So I was wondering if anybody has any other suggestions, I am going to cut the plug wires back to eliminate any corrosion.

 

[ocod]

If you didn't mess with the timing it could be the woodruff key on the crank or RV gear.

 

[FinnExplorer]

Twin carbs? Are the butterflies opening at the same time?

 

[tcapper]

single carb twin engine.I had to replace the flywheel in this engine a couple of years ago and it has been running well, so after several hours of trouble shooting,bringing the boat from my cabin to my shop in the city to do the "hard" stuff.