My latest carb question

[Waternut]

A little background...my primer failed and I never got around to ordering a new one so I cut the tubes going to the primer and attached them to the nipples where the choke plate used to go.

After replacing the fuel pump and cutting back the tattered spark plug wires my ski ran great for about 5 seconds and then bogged out because it was running so rich. I rejetted it and took it back out. It was still running funny and I noticed the that fuel was being dumped into the carb from those primer lines.
I unhooked the primer lines completely and plugged them as shown in the picture. The engine runs amazingly well with no hesitation at any RPM!! It will run until I stop it. However, if I let it idle for 3-4 seconds it runs all the fuel out of the carb and dies. Since I don't have a primer now that pretty much leaves me stranded.
Any ideas what's going on?

 

[WAB]

So it never died like this (after idle) when it had a primer? You should not need the primer to start a warm motor.

I can tell you it's NOT caused by the open nipples or the looped primer line. The open nips are above the throttle plate so they don't effect anything.

Wondering why you have a fuel filter on the return line though?? :scratchchin: Maybe that has something to do with it or maybe the line in filter is clogged. I'm aweful at jetting, but I would not think it's low popoff or jetting if it would idle normal before removing the primer.

 

[Waternut]

So it never died like this (after idle) when it had a primer? You should not need the primer to start a warm motor.

Well that is debateable since the primer required a lot of pumping when I bought the ski and completely died shortly after but no it never died before I disconnected all this stuff.

I can tell you it's NOT caused by the open nipples or the looped primer line. The open nips are above the throttle plate so they don't effect anything.

I would think so too since much more air flowing through the gigantic hole at the top of the carb instead of a tiny pin holes on the side. However, I put another piece of tubing and looped those nipples together to seal them off (quick sealing at the ramp). When I did that it idled better but if I touched the throttle, it died instantly.

Wondering why you have a fuel filter on the return line though?? :scratchchin: Maybe that has something to do with it or maybe the line in filter is clogged. I'm aweful at jetting, but I would not think it's low popoff or jetting if it would idle normal before removing the primer.

I have the fuel filter on the return line because that's what the guy had before me. When I replaced all the lines and filters to track down problems, I just recreated what was already there. Think I should take it off and run a straight line back to eliminate the filter and primer loop?

 

[vomitspot]

put on a mikuni 44
i hate kehein carbs!

 

[tor*p*do]

I also have a '92 750sx
Took me a while, but I finally got the carb working good. Keihins :thumbsdown:
Try this:
Run the fuel return line clean from the carb back to the tank.
No primer or filter. Use cheap auto fuel line.
Pull your fuel pick-up out of the tank and check the filter at the bottom of the fuel pickup (assuming stock pickup). Make sure screens and pickup tubes are clear.
Run auto fuel line from tank to carb inlet (bottom).
Put an inline LARGE fuel filter- not those POS cones,
Get a decent Yamaha filter with the paper media
and much larger to eliminate resistance.
I put the primer line in the fuel inlet line but others say to put it into the return.
If you dont have a working primer- dont worry about it for now.
A squirt of premix should wake her up for the day.
Try that: the clear fuel line looks cool but never lasted on my 750.
Sucked air, leaked, etc until I went back to auto fuel lines
Not pretty but they work good!

 

[Waternut]

I'll give all this a try tommorrow.

Man what a compounded problem I've got with this ski. Fuel pump, rebuild kits, jetting, popoff, fuel lines, primers, filters...the list grows about every week. But I keep getting one step closer. lol

 

[Mouthfulloflake]

I used a turkey baster to prime and start my kawasaki skis.

those dang Keihn CDKII carbs are hard starting when cold, for dang sure.
when you let it idle, and then it dies and doest restart, can you visually see fuel in the feed line to the carb?

is there a one way valve or vent on the tank? are they functioning as they should if so?

once its running, and pumping its own fuel, it should NOT empty the bowl, unless you have a weak fuel pump diaphragm, but it would seem that would be more evident at large throttle openings instead of idle.

is the pulse line ( that modulates the fuel pump diaphragm) in good shape and not leaking?

EDIT ( again)

Ive heard folks complain about that pretty fuel hose on the pulse line, its so flexible it can close off and restrict it.

replace that with a piece of automotive fuel line also during your testing.

 

[Waternut]

Well the reason I put the clear fuel lines in there was to help detech leaks and make sure fuel was in the lines. I'm 99% sure there is gas in the feed line after it dies. I will replace all with automotive line this afternoon.

 

[Mouthfulloflake]

if there is gas in the feed line when it dies, you probably have a seperate problem, like possibly a stator/pickup thats going out, early kaw 750 engines are prone to that.

 

[sflsurfrider]

seems kinda simple, but what if you raise the idle?

 

[Waternut]

No the idle is not an issue. I've got that thing set pretty high. If these fuel lines don't do anything then maybe this winter I will try and pull the stator and coil and all that fun stuff and see what needs work.

 

[Waternut]

Well the fuel lines didn't change anything. I will try to look into the stator.

Of course maybe I could put a choke plate back on and use this to my advantage as a kill switch of some sort.