HELP Still Major Fuel issues.

1

112motorsports

CLETUS
My ski is still pumping way too much fuel and I can't seem to figure it out. When it is barely running the PTO carb is just dumping fuel in like a garden hose. I have checked the needle and seats, the pop off over and over agina and it is still doing this. I have a remote pump feeding these carbs so there is one line from the tank to the pump, then two out of the pump to each carb and the pulse line. Then the returns are T together and feed back to the tank. I have a one way vale venting to the ATMOSPHERE. I keep getting several differant opinons on which way this should be venting. IN to the tank or OUT the the atmosphere. If anyone has any ideas and or experienced this in the past PLEASE HELP. I am at a dead end with this thing. Thank you for all of your help.
I am running 100 mains, 115 pilots, 2.5 needle and seat with a 115lb spring.
This is a standard 701 ported mod pipe ADA head dual 44.
Cheers,
 
DR3

DR3

Xscream Braaaap
Location
palm harbor, Fl
should be venting into the tank... i had a prob with mine doing that after rebuilding the carb but went right back through it and double checked making sure everything was clean. didnt find anything but redoing everything solved the prob :rolleyes:
def vent into the tank b.c as the fuel goes down it will create a vaccuum if not vented
 
kurtwolff

kurtwolff

Location
Mooresville, NC
Ok, here is a diagram for what I was saying.

Is it correct that, when running an external pump or a built in carb pump, the check valve should always let air into the tank? (vent inwards, not outwards)? That was my thoughts about it, but there seemed to be some confusion...
 

Attachments

  • ski.bmp
    1.8 MB · Views: 47
1

112motorsports

CLETUS
Then is there any reason why it would only be doing this on one carb and not the other? This is only happing on the PTO carb and not the other. Thanks agian.
 
1

112motorsports

CLETUS
Switched the vent around, changed to 95g spring 2.0NS 115-pilot, 120M and still is doing the same thing. It fired right up and sounded perfect on the trailer then we put it in the water and it was running perfect. We then put some more gas in it and bam back to the same thing. I am at a complete loss. Any ideas?
 
1

112motorsports

CLETUS
I don't think the needles are stuck. I put brand new 2.0NS in there and they pop off at the pressure according to Mikuni. I tested them 5 times each replaced the check valve that covers the main jet. I have checked everything time and time again and everything seems to be right. I just can't figure this out.
 
Big Kahuna

Big Kahuna

Administrator
Location
Tuscaloosa, AL
112motorsports said:
I don't think the needles are stuck. I put brand new 2.0NS in there and they pop off at the pressure according to Mikuni. I tested them 5 times each replaced the check valve that covers the main jet. I have checked everything time and time again and everything seems to be right. I just can't figure this out.
Click to expand...

If fuel is pouring in there, then the needle is open, it may the the lever that connects the needle to the spring that is hanging up........... but that the only way fuel is going to flow through like you have described.........


will it pop off repeadidly or just once, how does it compair to the other carb.
 
1

112motorsports

CLETUS
Yes the fuel is jsut pooring in there like a garden hose. It will pop off 26lbs time after time after time on the bench. The other carb is poping off at 25lbs and it is not encuring the same problem. Once I tear them down and go through them the boat runs great on the tailer and then as soon as there is load on the engine to does this. Is there a way that the O ring could not be sealing? I have just exhausted every resource I have and still cant get this damn thing to run. It is getting very frustrating.
 
1

112motorsports

CLETUS
The O ring on the seat. Here is some more Info on what I these carbs have been through. I had pumps on the carbs and then had JSS drill the return restrictor on the carb out and remove the pumps so I could run an external pump. Is there a way the seat could not be seating do to a faulty o ring? I have put 3 differant seats of new Needle and Seats in these things and I am still having the same problem. Could it be the gas tank itself, being too small? It is a shifter kart tank 2 gallons. I can't imagine that but heck that is about the only thing I haven't changed. Thank you for your in reading this and replying to it as well.
 
botizzle

botizzle

drillin like a villian
Location
Lake Lanier / LKN
Do you have another set of carbs that you could bolt on real quick?... just to see if the problem is the carbs or in the way you have the fuel/vent routed? That would at least determine where the problem is. just a thought
 
Kaveman

Kaveman

Born in USA(not Kenya)
Location
texas but soon tejas
I have been through carbureter training taught by a technician from Mikuni in 1995, and every level of training offered by Suzuki and Yamaha. All to say I know well how to tune a carbureter. Based on my own experience with jss, that is most likely your problem. I had a set that required CONSTANT tuning and could never get exactly right. Good luck and try another set of carbs.

The pump you are using is fine. I am running the same on dual Full Spectrum 48s.
 
SUPERTUNE

SUPERTUNE

Race Gas Rules
Location
Clearwater Fl.
I have had this happen before, but not to the degree your experiencing. I found that what cured mine was to replace the float arm (needle valve arm) and mount the carbs on the intake manifold to have the fuel pump sides of carb face the outside of ski and the fuel diaphrams facing the motor. The df62 pump should be fine... even though I don't run them on my std carb set-ups, but do use them on my Full Spectrum carbs. Kart tank doesn't make any difference.
Run fuel supply like this.... Like you have, 5/16 single line feed into df-62 pump from fuel pickup tube, then 'T' the two 1/4 outlets together then connect to the carbs, 'T' the return fuel lines back together then connected to a restrictor jet inline returning to the tank (70 main jet) should be fine, and make sure the fuel tank has its own check valve venting inward. You can also use a tiny restrictor and coil the hose, but keep in mind during a roll over it would seep fuel...
Chuck
 
douglee25

douglee25

m3booooy
Location
South Jersey
My bet would be on the n+s arm. My thought is that when you put the diaphram back in and screw the cover down, the needle has actually popped off the seat because the arm is bent up too high. Have you tried your popoff gauge after the diaphram and cover are back on?

Doug
 
1

112motorsports

CLETUS
No I haven't tried to pop them off after the diaphram cover is back on. I will give it a try. I just can't get why only one of the carbs is doing this is the fuel pressure is too high. I switched the fuel lines from the pump around seeing if it could be in the pump, but same results. I will replace the arm and the diaphrams when I get back in town tommorow night.
 
You must log in or register to reply here.
Top Bottom