94 spi won’t idle

[kidd10110]

I recently purchased a 94 spi with the rotax 587. The first time I took it out it started right up and idled fine. Once I was out if the no wake area I hit the throttle and the engine surged and died. I idled it back and brought it home. I replace all of the gray fuel lines and rebuilt the carb with a genuine mikuni kit. The pop off pressure is 26psi. The low speed adjuster is one turn out and the high speed is 0 out. Now it is difficult to start and almost impossible to idle. I thought it was a pop off pressure issue so I took the carb off and verified it. It was still at 26 psi and there is no leaking or bubbling. It runs completely fine above 3,000 rpm in the water. I have tried to run it off of a fuel can in my driveway to see if the selector valve, vents, sump or fuel water separator were causing the issue but there was no change. I’m out of ideas at this point. Any help would be greatly appreciated!

 

[Cheflen]

I recently purchased a 94 spi with the rotax 587. The first time I took it out it started right up and idled fine. Once I was out if the no wake area I hit the throttle and the engine surged and died. I idled it back and brought it home. I replace all of the gray fuel lines and rebuilt the carb with a genuine mikuni kit. The pop off pressure is 26psi. The low speed adjuster is one turn out and the high speed is 0 out. Now it is difficult to start and almost impossible to idle. I thought it was a pop off pressure issue so I took the carb off and verified it. It was still at 26 psi and there is no leaking or bubbling. It runs completely fine above 3,000 rpm in the water. I have tried to run it off of a fuel can in my driveway to see if the selector valve, vents, sump or fuel water separator were causing the issue but there was no change. I’m out of ideas at this point. Any help would be greatly appreciated!

I would try messing with the low speed screw since it would be the easiest way to get close to an answer

 

[seadoodle]

What do the spark plugs look like? Could be that the plugs fouled due to a rich idle

 

[mikidymac]

What is your idle set at? IT should be 3,0000 out of the water and 1,500 in the water.

 

[kidd10110]

I took it to the lake and turned the low end screw at 1/4 turn intervals. It rubs best where it originally was(1 full turn out). I’ll probably make it to the parts store to get new plugs. The idle is set to approximately 3,000 rpm out of the water. It still dies after Idling for about 5 seconds. Out of curiosity I cranked the idle up to about 2,500 rpm in the water and it ran fine. It’s just not really practical to have it idling that fast as it’s moving at 5mph or more.

 

[kidd10110]

What do the spark plugs look like? Could be that the plugs fouled due to a rich idle

 

[mikidymac]

That is not fouled at all if anything it is lean not rich.

 

[kidd10110]

Does anyone have any suggestions of other things I could try?

 

[mikidymac]

You need to rebuild the carb with a genuine Mikuni kit and new needle and seat. Sounds like it is starving for fuel. My guess it the 3 little transition fuel holes are not flowing.

 

[kidd10110]

I used a genuine kit with a new needle and seat. I’ll pull it apart tomorrow and check the transition holes. Thanks for the help!

 

[mikidymac]

Please follow my carb thread in my signature to do it correctly.

 

[kidd10110]

I took the carb apart again and I am still having the same issue. I made sure that all of the holes and jets were clear. I used a genuine mikuni kit and I followed the mikuni schematic to make sure everything is installed properly. I took it to the lake to try to tune it. I was still unable to get it to idle. I’ve attached a video of it running/ stalling. The only way I could get it to start was with the choke. It seems like it would quickly flood if I kept the choke closed. I would then release the choke and crank it until it started. It proceeded to idle for a few seconds then die. I went through this twice in the video. It seems like it easily floods with the choke on, then it will only run off of the left over fuel before leaning out and stalling. Does anyone have any other suggestions of what to try?

 

[mikidymac]

Did you use new needle and seats and check pop off and leak down?

 

[Jeffspx]

Just a thought, did you clean or replace the fuel valve? I see you mentioned carb rebuild and fuel line replacement, but no mention of the fuel valve.
EDIT: I now see you said you bypassed the fuel valve.

 

[seadoodle]

To rule it out, did you check the compression? I'm out of ideas.