650 waverunner pop off questions.

[randyj]

I've collected (cheaply) some 1990-1993 waverunners for the kids (Of course not me) to have fun on and of course, have had the usual gamut of problems. I'm always dealing with dirty carbs, water in fuel, trash, filters, etc. I've become a pretty good waverunner mechanic! One seems to have alot of problems with fuel. Seems to take off fine then run out of gas...can keep running at very low speeds only...it will run great at any throttle setting but too much throttle and it is just as if it runs out of fuel. I'm just wondering if there is a possiblity that there is too much pressure on the needle valve causing this problem. Is there such as thing as pop-off pressure for these engines? if so, what is it? I've about pulled my remaining hair out trying to keep these kids in the water.

I've done about all there is to do except check crankcase pressure....I'm thinking about making block off plates to do that with (how much pressure/vaccum should I put on the crankcase when checking it?)

[wmsky]

Re: 650 waverunner pop off questions.

It sounds more like you have some kind of restriction in the fuel line or the carb high speed circuit is not adjusted right. Have you replaced the fuel filter? Did you use a PWC fuel filter. I tried using an auto filter once and had similar problems. Turns out auto filters are made for the higher pressures of automobile fuel pumps and the low pressure of the PWC fuel system couldn't push fuel through fast enough at higher throttle. It could also be that the high speed screw needs adjusting. Try setting the high speed screw back to the factory default and follow the carb tuning article in the FAQ section of the SBT forums to adjust it.

Too high a pop-off usually just means you'll get a hesitation when you try to take off from idle. Once the needle has "popped off" the seat, it just stays open the same from that point all the way to full throttle.

[David3aces]

Re: 650 waverunner pop off questions.

auto filters work fine on WR111s...parts store guy says auto filter that matches waverunner filter fits 1978 Honda Civic with little 4 cyl engine and carb... I have used them for 10 years or more...however when they get old the element inside can restrict fuel flow...they won't work in 3 cylinder models...set high speed screw to 1 1/4 turns....check for exhaust leaks....it can't have any

[Technical Support]

Re: 650 waverunner pop off questions.

ONLY carbed auto filters work.

[randyj]

Re: 650 waverunner pop off questions.

Actually I've tried several different fuel filters. The one I favor is the clear glass with replaceable element. These are sold at Wally World and thru my outboard parts distributor. I really like being able to see the air bubbles and crud that it collects. The particular waverunner in question has alot of crud in the fuel filter. I'm almost positive that this is crud which has built up on the inside of the fuel line and is breaking away...and I don't doubt it is in the line past the filter and is causing blockage in the carb inlet. I'm frustrated that the only fuel line I can seem to find is that thick automotive stuff and nothing like the original...and I'd particularly like to have a nice roll of 1/4" clear fuel line for all these scooters I've got.