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View Full Version : Losing power at 2,200 rpm - Any ideas


johnpdodd
09-13-2004, 10:30 AM
MY '90 Tristar with new 4160 carb and fuel pump seems like it is flooding after pulling my daughter tubing at about 2,200 rpms for 10 minutes. Boat does fine off the ramp if we ski at 3,500. But if we start our day by pulling around 2,000 rpm - it basically bogs down and quits. Motor turns over fine but will not hold idle and stalls again. Have to wait about 10 minutes - then all seems well. Any ideas? I advanced the timing a little thinking it was getting too much gas not enough spark. That worked about one week. Distributor springs are original. Is it carb or fire? Fuel is clean. thanks

OhioProstar
09-13-2004, 10:34 AM
Have you checked your fuel filter? Could be you stir up some crap in the tank which in turn ends up gummin' up your jets.

johnpdodd
09-13-2004, 10:50 AM
Good thought. Fuel filter and water/fuel separator filter are new as is fuel pump. So I have ruled out bad fuel/bad delivery

OhioProstar
09-13-2004, 10:51 AM
Hummm....sounds like a JimN question.

JimN
09-13-2004, 11:23 AM
Advancing the timing doesn't give you more spark, it just changes when the spark occurs. Carb or fire- you didn't give enough info to tell. How old are the plugs, wires, cap/rotor, when was the last tune-up, have you checked the points/timing(with a timing light)/dwell lately? If these are all up to spec, check the fuel pickup tube and anti-siphon valve on the tank. If these are OK, check the fuel line from the tank to the fuel pump.

johnpdodd
09-13-2004, 11:34 AM
Thanks for the response> plugs, wires, cap, rotor and coil all brand new. I converted to electronic ignition this spring through SkiDim kit. Fuel line from tank to fuel/water separator then to fuel pump then to carb all brand new. Where is anti siphon valve and how do I tell if it working properly? That valve is definitely not new.

JimN
09-13-2004, 11:38 AM
The anti-siphon is on the tank outlet and usually has a shut-off valve on/near it. Speaking of this valve, make sure it's not partially closed. Aluminum body, attached to the pickup tube. You may need or want to slide the tank out a bit to get at these more easily. If you can, look into the tank to see if there is any debris in it.

johnpdodd
09-13-2004, 11:45 AM
You're talking that round aluminum/silver looking thing at top of tank that you attach fuel line to? I can access that through the circular access hole. There is also a fuel gauge there - right? Can I do what you say through the access panel or must I take out the floor to get a really good view? I've taken out the floor before - its a pain but I'll do it if you say. Also, how do I tell if the valve is half closed? Also, how much is a new valve? I am fairly handy and am in the camp of "If in doubt and it's cheap, repalce it!" Your thoughts are appreciated Jim

JimN
09-13-2004, 11:54 AM
If you mean the cylindrical part, about 4" long and about 2-1/2" dia with fuel line at each end, it could be a fuel filter. The valve has a little aluminum lever on it that should be parallel to the body of the valve. It may not have one, just an anti-siphon which it the part screwed into the aluminum block on top of the plate holding the sender. This can be removed by putting a clamp on the fuel line, then removing this by loosening the hose clamp and sliding the line off, making sure it doesn't drain into the boat. Unscrew the valve and see if it has anything stuck in it. If it does, you can stick a wire in to push the ball forward so the clog can be flushed/blown out the other end. While you're at it, pull the pickup tube and check this out, too. It may have a coiled wire in it, but should flow totally freelly with air or gas.

johnpdodd
09-13-2004, 12:04 PM
Will do Jim. thanks. So it sounds like you don't buy a new one - you just check and unclog?

east tx skier
09-13-2004, 02:47 PM
John, if you just got your 4160 from skidim, you might want to adjust your idle a bit, too. Probably won't make a difference as far as your cutting out at higher RPMs, but when I replaced my carb, the idle was adjusted just above the verge of stall. It would stumble at idle. I adjusted it up to about 620 rpms and it runs beautifully.

JimN
09-13-2004, 03:03 PM
I would clean it out if there's nothing that can't be removed, but if it's badly corroded or the ball is stuck, get a new one.