motor dies when I reduce throttle

[doehunter]

C40PLRS
'94 year, 2 cylinder, 2 stroke.
I ran it on the earmuffs in the yard. Idle is good. (no tach so not sure RPM but it sounds good)
Works good coming out of neutral into forward and advancing throttle.
If I take the throttle up pretty high and then slowly start returning towards Idle, it will try to die. Sometimes while it's still pretty fast, sometimes closer to slow speed, sometimes it doesn't do it. Advancing the throttle usually fixes it. If I don't advance the throttle, it will die all the way.
After it does die, I can put it in neutral and it fires right up, real easy.
The tank is almost empty, (maybe an inch or so) but it's fresh.
It has new plugs but I haven't checked to see if they are the right ones.
They were in it when I bought the motor.
Haven't had it in the water yet.
Ideas?
My plan was to put it in the water and see if it still behaves that way.
Jim

[boats.net]

May need to clean carbs but need to put it in water in try it. Don't rev engine high in neutral, could result in severe engine damage.

[doehunter]

I guess high is a relative term.
How high would you consider too high?
I was just goosing it, not holding it at high speed, but not sure how much is too much.
Yep, going to the water soon.
Part of me thinks if the high speed jets were clogged it would bog when I advance the throttle.
I hope it's not an electrical issue. part of the 703 control housing is broke off and missing.

[boats.net]

Over 1500-2000 rpm's is too high in my opinion but there are a lot of opinions on that subject.

[DougBradlow]

motor dies when I reduce throttle

Clean and blow out the carbs,and flush the fuel lines clean or replace fuel filter.Make sure you have no vacuum leaks at the intake manifold or fuel lines.If all is done right and if your problem is a fuel problem and it sounds like it is your motor should run great.2 strokes need spark,fuel,air and compression all in the right time to run good.Always check the compression first on all cylinders to make sure you have even or close to even compression within 5 psi of each cylinder. If you do then the next step is to make sure you have spark if spark is strong it should be a blue spark at the spark plug ends.Next step take a fuel sample from the tank and float bowels,look for water in the fuel or sediments.Water or dirt in the fuel can cause severe engine damage.Highly recommend a water separator filter to catch any water that may be in your fuel before it goes to your engine.

[doehunter]

thanks.
I ran it on the water last weekend.
New tank, new gas.
it ran fine for maybe a half hour then started dying on the water.
Other problems got in the way so I got side tracked.
I want to say it got to where it didn't want to start and when I checked, the fuel line bulb felt empty and took a lot of pumping to feel good again.
That would indicate air leaking in on the tank side of the bulb somewhere.
EDIT- or one or both carb bowls went dry from float sticking in up position?
The issue that side tracked me is, it quit coming out of forward gear.
I looked last night and found the end of the control cable came loose inside the 703 con*****er. (the swivel piece, not the very end)
I stuck it back in the jacket and it operates now, but I can pull on it and it comes off again. The crimp is a little loose.
Trying to figure out a way to tighten it up so I don't have to buy another cable.
I'm wondering if the teleflex after market cables would fit?

[boats.net]

703 and 704 control box have a slot that cables drop into(slot on cable), they don't have a swivel for cable anchor that may be a Moorse control. The Teleflex 3300 type cable is same as Yamaha.
Check that gas tank is venting, check for air leaks in fuel hose connections, if primer bulb sucks flat then have a fuel restriction in hoses or pickup.

[doehunter]

703 and 704 control box have a slot that cables drop into(slot on cable), they don't have a swivel for cable anchor that may be a Moorse control. The Teleflex 3300 type cable is same as Yamaha.
Check that gas tank is venting, check for air leaks in fuel hose connections, if primer bulb sucks flat then have a fuel restriction in hoses or pickup.

At the end of the cable jacket is a crimped spot. Then there's about a 6" tube, then there's a rod that sticks out that's actually attached to the cable.
The swivel I was referring to is the crimped connection for that tube. It lets the tube swivel a few degrees. It's on the Yamaha and Teleflex cables.
That connection is what came apart.

Anyway,
I plugged it back together today and tightened it up as best as I could with some wore cutters. Moved the wires around a little in the 703 box and put it all back together.
I ran the motor about 20 minutes.
The shifting worked fine. I didn't get shocked, and the motor didn't die.
Hmmmmm!
Well the thing to do now is to test it on the water again.
Jim

[DougBradlow]

fuel restriction

Sounds like a fuel restriction in the pick up tube in the tank or a bad fuel pump.Remove all fuel lines from the carbs and pump the primer bulb to see if fuel flows threw the lines check the pick up tube in the tank for obstruction if all is clear replace the fuel pump.As far as your cable goes replace it.They are not that expensive and it is better to be safe than sorry.