Thread: Lean/high idle
08-15-2010, 10:02 PM #1
So, my buddy has a 98 XP with the 787. He changed his fuel lines, cleaned his RAV valves and some other misc stuff.
He replaced the fuel lines with 1/4 black fuel line from the autoparts store.
The ski ran kind of off from what it normally did. He then hooked up an aftermarket trim box and the ski sat for a few weeks.
The other day we went to fire it up and it wouldn't run. We found that it wasn't getting fuel. I pulled the fuel supply line and saw that red/orange gas was coming out. The gas in the tank was maybe a month old at most. Not sure what caused it so we pulled his carbs, flushed the lines, got rid of his aftermarket filter and hooked everything back up. This time using the stock filter, which is clean and functional.
Being a Sunday and a spur of the moment thing, well pulled apart his carbs and just used some carb cleaner to spray them down. I didn't pull the jets or anything, just took them apart and glanced inside and sprayed them. Dried them and put them back together. The diaphragms were pretty bad looking and should be replaced but we reassembled anyway and put them back on with the idle screw all the way backed out.
When we started it, it took a second to pull gas to the carbs then fired right up and started idling high, real high like it was lean. Opening the throttle just made it rev higher and it sounded horrible. The throttle cable has a slight amount of play so it's not over tight and like I said, the idle screw is backed off.
Pulled a plug and saw it's getting oil. It has a smokey oil smell to it and it gets very warm, very fast. Probably ran it 3-4 times messing around for no longer than 10 seconds each time.
We pulled the carbs back off, put black liquid gasket on the carb gaskets and tried again, same thing.
Anyone have any suggestions?
Tomorrow we plan on by passing the fuel selector, it seems restricted. Other than that, I'm kind of at a loss.
08-16-2010, 07:19 AM #2
- Join Date
- Sep 2009
not sure but doesnt the 98 xp have 5/16 lines? other than that it sounds like you have an air leak. when you bypass the selector make sure you use the res line as your feed to the seperator and plug the old on line. can you see if the throttle plates are closed?
08-16-2010, 02:27 PM #3
Alright, well his is a 97. But I think I do remember seeing a 5/16 to the filter, then a 1/4 from there to the carbs. I have no clue what was in the ski before. I'll have him upsize that 1/4 line.
I also think it's an air leak, I think we're going to have to re-do the carb gaskets.
08-16-2010, 09:26 PM #4
Well, here's what happened tonight:
We bypassed the selector switch. Ran 5/16ths line from the reserve to the filter and a 5/16th to the carbs. Looking at the fiche in the manual, there is a 5/16th to 1/4 adapter that goes in-line to the carbs but we could not find one. I don't think that could be causing this but I'm no expert. Maybe that increases velocity or something? We plugged the "On" feed on the pick up.
There is 1/4 going from the returns to the Y then 1/4 to the return on the pick up. The vent is vented.
It now idled better. The idle screw is backed off 100%. The low speeds are set to 1 turn out. The throttle cable and oil cable has a small amount of slack. The throttle plates are slightly open, is this correct? Or should they be sitting 100% closed at that point?
We sprayed WD40 around the base of the carbs and heard no difference in idle. Here's were it got wierd.....
Started it up. Idled fine for about 10 seconds, then it started climbing high. Then when he pulled the lanyard it keep going, he pulled the choke and killed it. Obviously this thing is really, really lean for it to do that.
I guess the next step is to pull the carbs and put new gaskets in.
Any other suggestions? Would the throttle plates being open slightly cause this?
08-17-2010, 03:01 PM #5
Just bought two new carb kits and carb to motor gaskets.
Any one have any suggestions on the throttle plates being open a hair? Should they be closed?
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