Throttle acting funny???

[rhillman75]

I have a 1999 Mariner 40HP Jet 30 3cyl 2 Stroke that was recently gone through at the marina. To give you soe insight... I had a guy thatdid not tighten down the lock nuts for the idle timing, max. spark advance timing, throttle stop, or the WOT throttle stop screws. I found this out when the motor literally quit when I was on the water. The marina set everyhting back to "factory" settings but when they set the carbs... they set them to the factory 1-1/4 fromseat. When I was on the water at WOT I notived a "miss" very light but noticably on the motor when I backed down. What would cause this??? The filter and plugs have been replaced. The gas tank is clean or so the fuel filter seems to say that. I'm wondering if this is a coil or if they tested this at the time of the work. It idles fine...but I do have less power now than I did befor. But I did notice before that if the carbs were set to 1-1/4 out from seating I did lose power before I adjused them to 1-1/2 out from seating. Any thoughts???

 

[j_martin]

Re: Throttle acting funny???

I have a 1999 Mariner 40HP Jet 30 3cyl 2 Stroke that was recently gone through at the marina. To give you soe insight... I had a guy thatdid not tighten down the lock nuts for the idle timing, max. spark advance timing, throttle stop, or the WOT throttle stop screws. I found this out when the motor literally quit when I was on the water. The marina set everyhting back to "factory" settings but when they set the carbs... they set them to the factory 1-1/4 fromseat. When I was on the water at WOT I notived a "miss" very light but noticably on the motor when I backed down. What would cause this??? The filter and plugs have been replaced. The gas tank is clean or so the fuel filter seems to say that. I'm wondering if this is a coil or if they tested this at the time of the work. It idles fine...but I do have less power now than I did befor. But I did notice before that if the carbs were set to 1-1/4 out from seating I did lose power before I adjused them to 1-1/2 out from seating. Any thoughts???

Factory setting is a starting point. Each engine/location/setup needs to be tuned a bit from there.

Idle mix a little lean shouldn't cause any trouble at WOT, but a mis-adjusted float will. Given the sloppy work this shop is doing, that's a distinct possibility. The big problem is that if it's leaning out a bit at WOT, the next step in the failure sequence is a hole in the piston.

It ain't rocket science, but it is a bit picky. I'd get the manual and go through the carbs, and the linkage adjustments myself, taking my time, not like the harried shop that can't even tighten down the lock nuts for lack of time.

When I bought my boat with the XR4 engine on it, it was a 50 mph sluggard. After uncovering and fixing a dozen small errors, including wrong parts introduced by the "certified" Murkery mechanique, I down have a skip stone that goes in the mid 60's.

hope it helps
John