1991 SeaDoo GT - must be starving for fuel

[eric.smeltzer@yahoo.com]

Well I got these about 3 years ago. The 1991 GT would run for about 12-15 minuets (in the lake) like a champ full throttle and on the trailer forever. Then bogs out and stalls. Let it sit for 5 minuets and it will pop right off and speed into the launch with power and purpose. However if I attempt to restart it immediately after it stalls out it just cranks and cranks. choking it or holding it wide open makes no difference. I don't see any air bubbles in the fuel lines between the 2 carbs. When it starts to bog out I have tried choking it, power does not return and it prolongs it stalling out completely for maybe 30 seconds to a minuet longer (no real difference). When I machined the R.V. cover because the clearance was .020 and spec was .008-.013. I have it at .008-.009 right now. will that increase vacuum or pulse pressure to the carbs? It does not have an auxiliary fuel pump it relies on the the carbs pump. Compression was between 135 and 140 on both cylinders. I'm running pre-mix in the tank as well as using the injection pump. I've replaced all the fuel lines and fuel filter. rebuilt the carbs. set pop off to 21psi. It occurred to me after machining the R.V. cover that the carbs filled much faster then before. After the R.V. cover repairs it stalls out much faster now after just a few minuets on the water. let it sit for 5 minuets and it starts up and runs into the launch but I had to restart it a few times and almost ran my battery dead to get back to the launch. Even tried removing fuel cap to listen for "hissing" vacuum leaking out of the tank. After the initial fuel line replacement and carb cleaning it would run on the trailer with the hose for an hour with no issues 3500 rpm or close to it. there is not backlash to speak of with the R.V. shaft. The tell tail "pee" holes I get 2 streams sometimes its only strong enough to go a few inches other times they shoot 3 feet +. I noticed that the head towards the rear or the pump that the rear right corner of the head seams to be hotter than the rest of the heads. pry has some sand build up. The oil pump timing is correct. Even now it will run on the hose for ever. Do the exhaust systems ever plug up? I seam to be getting good somke out of the exhaust by the pump with it running on the trailer with the hose hooked up.

HELP - I'm close to lighting a match!!

What have i done you ask? well here is the list.

* Replace the entire fuel line system
in tank fuel filters and pick up fuel line
pick up pass thru tubes at the fuel tank collector cap (cap with the 3 fuel line and 1 vent)
fuel line for vent system with new check valves
fuel lines to fuel selector switch
fuel lines from selector switch to filter
fuel filter
return fuel line
* Rebuilt both carb with SBT kits ( Mikuni )
set pop off pressure to 21 psi on both
* Rebuilt the jet pump with ware ring and bearings had propeller straightened and sharpened i guess he
* Replaced spark plugs (Both cylinders have 135-140 psi compression)
* Replaced stater
* Replaced Voltage rectifier
* Replaced CDI
* Replaced oil injection lines / Verified oil injection pump is functioning
* New AGM Battery
* Added voltage gauge (running at 13.5-14.5 depending on throttle)
* Machined R.V. Cover to obtain .008 clearance when I purchased the ski it was at .020) Spec .008-.013
* 2 Cycle oil feed and return lines with new filter

 

[mikidymac]

The SBT carb kits are the issue. Rebuild with new genuine Mikuni carb parts including new needles and seats and the correct springs.
And I would also replace the fuel selector with a new one.