Im lost. Please help

T

T_bone664

New Member
I have a 1992 seadoo gtx with the white rotax 587. I was just given the ski by my grandpa. It died on the lake about 4 years ago. It’s sat since. When I got it I pulled the carbs and rebuilt them. Pulled the tank and the pickup tubes inside the tank had disintegrated. Replaced tubes. Fuel filter and 2 stroke oil filter. Took it out for a ride and it ran great for about 10-15 minutes then died. Kinda sounded like it didn’t have fuel. Just bogged out. Fired right back up went about 25 yards then bogged out again. I can’t figure this out. Had it out 2 times since does the same thing. Runs great for about 10-15 minutes and then dies. It will fire right back up after every time it dies. Thought it was maybe overheating but after running it hard for about 10 minutes the whole engine only ranges from 140-150. Doesn’t have the old grey fuel lines. I’m lost on it



New parts-
Rectifier
Fuel filter
Oil filter
Spark plugs
Carbs just rebuilt with genuine Mikuni rebuild kits
Fuel tank flushed and refilled with high test
All cooling lines flushed and cleaned thoroughly


ON THE WAY BUT NOT INSTALLED-
Fuel valve petcock for the fuel/reserve/shut off
 
See if the carbs will pull fuel through a short hose from a small remote fuel container.
Check fuel tank check valves
Check compression
 
tobytd said:
See if the carbs will pull fuel through a short hose from a small remote fuel container.
Check fuel tank check valves
Check compression
Click to expand...
Compression is 130 on both cylinders. Carbs will pull fuel. But the fuel tank check valves? I’m not sure I know what you’re talking about
 
Fuel tank has two 1 way check valves
One up high towards handlebars, lets air in to keep tank from collapsing
The other one holds 2 to 3 pounds of pressure.
If everything is working correctly, when you open the fuel cap, you should hear a slight hiss.
 
tobytd said:
Fuel tank has two 1 way check valves
One up high towards handlebars, lets air in to keep tank from collapsing
The other one holds 2 to 3 pounds of pressure.
If everything is working correctly, when you open the fuel cap, you should hear a slight hiss.
Click to expand...
Okay. Something there might be messed up then because when I open the tank no hiss no air escaping nothing. I’ll check those now
 
tobytd said:
Fuel tank has two 1 way check valves
One up high towards handlebars, lets air in to keep tank from collapsing
The other one holds 2 to 3 pounds of pressure.
If everything is working correctly, when you open the fuel cap, you should hear a slight hiss.
Click to expand...
Okay. So just checked. One by the gas cap is good. One coming off the tank going up by the handlebars is bad. Gonna go ahead and order two new ones. Do you think that would cause the issue?
 
If the pressure relief valve holds 2 to 3 pounds which it does, supposed to I mean, if it’s bad and not holding those pounds opening the gas cap a crack would not help. Does that 2 to 3 pounds not help the fuel get to the carb? I know that the carb pulls fuel but does that few pounds of pressure built up in the tank not help?
 
tobytd said:
OP said upper check is bad…lets air in to keep from having a vacuum in tank
Click to expand...
Possibly found the problem. While waiting on the check valves to come in figured I would go back over all fuel lines and check if they had any valves. While doing so found that both oil injection lines (3.5mm lines) were cut off and not even there. Saw this and immediately knew the engine was probably done for. Compression tested again. And borescoped the cylinders to check the walls. Little pieces of metal flake on top of pistons and slight scoring on the walls. What I don’t understand is this thing has been rode for years like that. My grandpa has never done anything to it other than basic maintenance. Compression test cold and dry is still 132-135. How is that possible?
 
T_bone664 said:
Possibly found the problem. While waiting on the check valves to come in figured I would go back over all fuel lines and check if they had any valves. While doing so found that both oil injection lines (3.5mm lines) were cut off and not even there. Saw this and immediately knew the engine was probably done for. Compression tested again. And borescoped the cylinders to check the walls. Little pieces of metal flake on top of pistons and slight scoring on the walls. What I don’t understand is this thing has been rode for years like that. My grandpa has never done anything to it other than basic maintenance. Compression test cold and dry is still 132-135. How is that possible?
Click to expand...
 

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Only way that’s possible is if it was running pre mix and even that doesn’t really make sense as there would be oil all over the engine bay.
 
burtshaver2021 said:
Only way that’s possible is if it was running pre mix and even that doesn’t really make sense as there would be oil all over the engine bay.
Click to expand...
That’s what I’m saying. My grandpa said he never pre mixed it. I’m dumbfounded how this thing still has compression. I pre mixed some fuel and put it in the tank. Taking it to try it out. If it still shuts off SBT has an engine ready to ship to me. Just gotta call them back.
 
T_bone664 said:
That’s what I’m saying. My grandpa said he never pre mixed it. I’m dumbfounded how this thing still has compression. I pre mixed some fuel and put it in the tank. Taking it to try it out. If it still shuts off SBT has an engine ready to ship to me. Just gotta call them back.
Click to expand...
The first time you rode it since it was last rode in roughly 2016 you pre mixed the fuel? You haven’t ran it on straight gas?
 
burtshaver2021 said:
The first time you rode it since it was last rode in roughly 2016 you pre mixed the fuel? You haven’t ran it on straight gas?
Click to expand...
It’s never been premixed. So when it ran in 2018 it must’ve been running on straight gas. Somehow still has compression. Just now got back from taking it out with premix. Runs like a top. No stalling. And temperatures are staying at 130-140. So 10 degrees cooler with the premix. Guess I’m just gonna pre mix it until it gives out. Then put a new motor in it.


THANKS TO EVERYONE WHO HELPED. I FEEL SO DUMB NOT RUNNING A BORE SCOPE FIRST. CHECK VALVES ARE STILL GONNA BE REPLACED ALONG WITH THE FUEL SHUT OFF. THANKS AGAIN FOR ALL THE HELP
 
Make sure you cap off the nipples on the intake manifold. If they start sucking air premix will not help.
 
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