1989 580 will only idle.

[knied1]

I have a 1989 Seadoo 580 (Yellow Motor) all stock
I can get it to idle on the trailer fine, but if I give it throttle there is a severe hesitation, and will stall. I have removed the carburetor, and cleaned it out, put it all back together and it will run fine for a few minutes, then back to running like crap. I assumed it was the gas, so I drained the tank, and once again, pulled the carb apart, cleaned it our, it ran fine for a little bit, and then like crap again. I have checked the filter, and soaked it. I have also pulled the filters from the tank, and soaked them, so I know they are clean, there are new plugs, and it does seem to get strong spark.

The needle and seat look fine, but I did replace them with a spare that I had. The only difference is the spare has the rubber tip on the needle, and the original didn’t but both were 2.0 size.

I have been chasing this problem for a couple weeks now, and honestly am ready to just dump the ski. Any suggestions will be appreciated.

 

[Dr Honda]

Did you check the fuel pump?

What ski is it??? The twin carb models had a vacuum fuel valve that can be going bad.

have you checked the compression? Very low compression will give similar issues. (should be better than 140 psi)

 

[knied1]

its the 1989 580, from what i am told it was the only one (580) made that year Single carb yellow motor, the compression is Just under 150 psi on mag side, and just over 150PSI on the other.

I pulled the fuel filter cup & cleaned it, (the onle that is right next to the pump). as i was cranking the ski i watched it fill, it was a nice steady flow, i do not believe it is the pump, but is there a good way ot test the pump? I may be wrong and the pump is my problem.


Thank You

 

[Dr Honda]

To check the pump... just hook a pressure gauge to the output side. You need about 23 to 29 psi (as I recall) to reach your pop-off pressure... SO... you will want at least 30 PSI.

Just because it was flowing to fill the bowl, doesn't mean it has any pressure behind it.

Speaking of that... when you pulled the carbs apart... did you verify the pop-off pressure?? (very important)

 

[knied1]

I’m a little confused,

People on this forum are saying that the pop off pressure should be around 30 psi, but according to the shop manual it should be 11 1/2 to 12 ½ psi,

What am I missing.

Also can I simply put a hose, and gauge in the outlet side of the fuel pump to test it? And if yes should the pressure be 30, or closer to the 11 ½ to 12 ½ psi?

I attached pages from the shop manual for reference.



Thank you,

 

[Dr Honda]

Yes, you are right. THe round body BN carb should be 11.5 to 12.5 psi. On my 90 Si... I removed the BN, and replaced it with a SBN before I ever even put it in the water.


The procedure you are showing is for testing with the carb in line. I normally will test it just on the output line of the pump. (when there is an external pump) As long as you can build more pressure than the Pop-off pressure... you should be fine.

 

[knied1]

I read a few other posts where the rectifier created similar issues, and in the same post the person stated that he also had this problem with the ski out of the water on the flush kit, but it went away in the water. Since I had a spare rectifier I threw it on, and headed to the local launch. It was getting dark so I was not able to drive the ski at all, but I backed it down the ramp until the ski was in the water. It fire up, and idled good, but when I hit the throttle it bogged down like it was flooding, I was able to feather the gas and get it to raise RPM’s but not as high as I could get on my 93 Sp 580. Both skis were strapped down to the trailer.

I am starting to think that I just have spent too much time chasing an issue, and missed the most obvious thing.

Now I have the ski on the trailer, idle is good, but what seems to be a flooding condition. When I got the ski home I pulled the plugs, and they were black. (plugs are new and have only about 45 minutes on them.) I am going to get a new set of plugs, and start over. Please read below, and comment if I am missing a step, because my head is spinning, and am getting frustrated.

New plugs, gapped to .025
Spark seems real strong (I will cut ¼” off the wires, and re-attach just to rule it out)
Idle screw 2 turns after contact
Low idle screw 1 ½ turns (starting position)
Compression is 151, and 148

Black plugs, turn mixing screw out
White plugs turn mixing screw in.


thanks again