Freestyle Fuel Starvation

Citizen

Citizen

Location
Coeur D' Alene, ID
Been working on the break-in period on my new ET967 and shes hitting like a train. Ran into an issue today which was the first time i was taking her above low/mid throttle. At about 3/4 throttle ski runs out of fuel and dies. First time caught me off guard and I went right over the nose.

I am running dual taper bored 46's w/ 125p 135m and have lows out ~1 turn. Started the day with highs out 1/2. Thinking i just wasn't getting enough fuel i slowly adjusted my highs out 1/4 a turn till I am now 1 1/2 out with same issue.

Only thing i can think of is at high RPM the motor is pulling more fuel than my system can supply.

I am running a thrust 4.3g tank with a main/reserve selector. 2 lines into fuel selector and 1 off selector w/ fuel filter inline into first carb, which then feeds my 2nd.

Anyone else run into this? Not sure what to do other than install a new filter in case its plugged up a bit, but it looks fine and ski rails on low to mid. Should i be running separate fuel lines off selector to each carb?

Thanks for the help guys.
 
Citizen

Citizen

Location
Coeur D' Alene, ID
zzylstra said:
Sounds like you need to run individual fuel lines to each carb

What needle and seat are you running along with popoff pressure?


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Click to expand...

Running a 2.0 needle and seat as someone recommended on here. I have a 2.3 needle and seat? In my spare parts. That was in there before. I am not sure that my 2nd carb has a pump on it or not, It is thinner back there than my 2nd carb and would have to tear it down to make sure. It does have the holes for fuel and pulse lanes, just no fitting installed in them.
 
zzylstra

zzylstra

Location
Valley Springs, CA
Hmm so your saying you have a slave 46mm carb set? That's new to me. I would recommend feeding each carb separately. You needle and seat seems right on as long as you running in the low 20's for popoff


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jetpilot36

jetpilot36

Location
Fort Worth
if the cases aren't fitted with dual pulse lines, I suggest putting a dual pulse line in. basically you wanna turn that slave carb into a pump carb identical to the first carb. and also 2 separate feed lines for each carb. and make sure your tank is vented properly.
 
Citizen

Citizen

Location
Coeur D' Alene, ID
jetpilot36 said:
if the cases aren't fitted with dual pulse lines, I suggest putting a dual pulse line in. basically you wanna turn that slave carb into a pump carb identical to the first carb. and also 2 separate feed lines for each carb. and make sure your tank is vented properly.
Click to expand...

It does have dual pulse lines, which i have tee'd into my first carb atm. As for venting it should be good to go. Sealed except for one way valve for breather.
 
jetpilot36

jetpilot36

Location
Fort Worth
Citizen said:
It does have dual pulse lines, which i have tee'd into my first carb atm. As for venting it should be good to go. Sealed except for one way valve for breather.
Click to expand...
If you only have 1 pump carb, then try capping off one pulse line and just use the one pulse line. But if it were my ski I would be running pumps on both carbs. Hence the 2 pulse lines

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smoofers

smoofers

Rockin' the SQUARE!!!!
Site Supporter
Location
Granbury, TX
Citizen said:
It does have dual pulse lines, which i have tee'd into my first carb atm. As for venting it should be good to go. Sealed except for one way valve for breather.
Click to expand...

If the pulse lines are tee'd together then I think that's probably the issue. One piston is generating a positive pulse while the other is generating a negative pulse. The pulses are cancelling each other out and your carb's fuel pump is seeing a very weak pulse and can't keep up!!!!!

Un-tee your pulse and plug one of them off. Go ride and report! I'd bet $100 that fixes your problem.
 
Harbor

Harbor

Location
Stockton
opposing pulses in each crankcase and T'ed pulse lines, the pulse signals are working against each other. I'd expect only quick short duration (1/2) fuel pump diagphram stroking instead of longer duration full diagphram stroking, as well as a 50% or greater loss in fuel pump volume output.

Agree with zzylstra and jetpilot36, seeperate feeds, dual pumps or a high volume pump And separate the pulse lines

Edit: agree with smoofers too
 
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Citizen

Citizen

Location
Coeur D' Alene, ID
smoofers said:
If the pulse lines are tee'd together then I think that's probably the issue. One piston is generating a positive pulse while the other is generating a negative pulse. The pulses are cancelling each other out and your carb's fuel pump is seeing a very weak pulse and can't keep up!!!!!

Un-tee your pulse and plug one of them off. Go ride and report! I'd bet $100 that fixes your problem.
Click to expand...

99% sure this is it. I noticed when priming my carbs by covering them with my hand that there was very little suction compared to my old motor, and could feel it actually pushing back a little. My buddy assured me that was most likely normal and due to the new motor, but it seems really weird to me. I will block off one pulse line and test for now, and upgrade carbs as soon as i can.

Will report once I get a test ride in.
 
eastcoastjumper

eastcoastjumper

James
Site Supporter
Location
Long Island
If you have dual 38's( with the jetting your specified) and your engine is shutting off when you ride full throttle you better hope your piston isn't lean seizing over and over. The suction when you put your hand on the carb is from your pistons seal/ compression, not the pulse line. You should do a compression check asap. Also upload pictures of your carbs. Sounds like you have some Frankenstein issues going on here
 
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