Motor has always run fine. Had a lower unit replaced, and while it was in the shop I had the carbs rebuilt and a hot foot installed. It has run like junk ever since. The symptoms are:

1. Will not idle. Idles extremely rough and slow and then putters out.

2. Has become very tough to start, and when I finally get it started there is a huge smoke cloud, then the smoke goes away. Have to have the throttle hammered down to get it to start and run.

3. After idling onto the trailer bunks, I give it throttle and it bogs down and shuts off. At this point after restarting it every time I mash the throttle to push it on trailer it bogs down and dies. Also, at this point, I can't back it off the trailer without the engine bogging down and dying.

4. It used to run at wot at about 5000 rpm. Now, after I get it on plane, max rpm is about 4400, then slowly fades to between 3800 and 4000. If I make a sweeping turn, it briefly goes back up to 4200 rpm then fades back down to 3800 and 4200.



I'd appreciate any and all thoughts.

Manual fuel pump diaphragms.

do you mean these pumps?

Or do you mean the bulb between the tank and the motor?

The arrows point to the manual fuel pumps or low pressure fuel pumps. The diaphragms are a known yamaha problem. They rebuilt the carbs on this motor in the picture?

No, I found this picture online. I'll see if I can change these and see if it helps.

Take it back to the shop that did work. I had carbs on Merc rebuilt once a got some bad needles. Before mechanic replaced them he made me replace all the fuel lines. You could have bad fuel lines flaking on inside. If so you will chase your tail tearing down carbs.

What year is your engine?

2006.

Update:
Turns out the shop that did the original work did not change the plugs, which were fouled. Service Marine in Emory changed em, synced the carbs and adjusted the idle and it runs like a top now.

Should have gone to Service Marine the first time.