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Fuel starvation from 0-2800 rpms

3440 Views 10 Replies 5 Participants Last post by  Green_Monkey23
OK guys, my `96 SLT 780 runs great after 2800 rpms. At idle I have to choke and flutter the gas for it to take off. I took the carbs apart and cleaned them but did not change diaphrams as thet looked good. Fuel pump, shutoff valve, compression are all good. Since it revs up to 6400 rpms and has as much top end power as when new I would not think I have a fuel delivery problem, but can the fuel pump be bad down low and then good on top? BTW mt popoffs are 19, 21 and 21, thanks Mike
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What are your low speed adjustment needles set at? You might just have to open them up a touch and give it a little more fuel.

If it likes the choke like you've mentioned, it's a lean problem.

Just a thought
Yes I have the low speed at 1 3/8 out but I have taken them to 2 1/2 without any improvement
What size is your low speed jet? It may be too small... Or you're pop-off pressure could be too high. Or you could have low vacuum pressure operating the fuel pump, it could be too low at low rpms to properly pump the fuel...
It was working great for seven years with the same lo speed jet. It`s more apt to be lo vacuum for the fuel pump, but I get great top end power. How do check lo vacuum at the fuel pump? Also I was thinking there might be some crud inside the jet as I don`t usr stabilizer, as I run the ski all year. Thanks guys, and BTW this is a great forum!! Mike
Have you checked compression? You might have some rings going south and the engine can't produce enough vacuum till higher rpms.
My compression is 110 on all 3 cylnders. When I check my return line for fuel flow at idle, there is a steady dripping of fuel. Not sure what the flow should be though but it is not a continuous stream but a very fast drip.
What happens when you turn the low speed screws out more?
PolarisNut said:
What happens when you turn the low speed screws out more?
I does not affect things much. It still bogs and hesitates at lo rpm`s.
How much fuel should flow out of the return line at idle??
Should be a little more than a fast drip, basically a small steady stream. I believe you're pulse signal is weak. This could be as simple as a leaky pulse line or as complicated as a worn top-end.
Small problem...

Sorry for your time.... Why i can't see images on this resource?
My Browser is: Opera.
Thank you.
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