Help a brotha out

[WILKEY]

I am completely stummped on this one. Basically bran new everything . I had to take a week off of thinking and messing with it cause I was about to put a bomb in the ski and walk away. We recently put 49 full specs and a pfp on and I had jetmaniac redo the electrics. Ski runs like a raped ape for 10 min or so then will just die like its out of gas. Let it sit for about 30 seconds and it fires right up and rips for a little longer. I want to try a oem coil I think but what are yalls thoughts? I think its a ocd coil jet used.

 

[naticen]

Sounds like a lack of fuel to me. 30 seconds is not enough time for electrics to cool down and work normal, but it is enough time for some more fuel to slip by a clogged filter or fuel selector.

 

[MADMAT]

odd!!

 

[speedysprocket]

I'd try the coil. She gets plenty of fuel. I'm sure Dan has a surplus of coils you could try to see if it's the problem... And don't forget that your electrical box didn't come back perfect; there could be other problems in there...

 

[JetManiac]

Tank vent?

 

[Blue]

I agree with jetmaniac. Same thing happened to me once new tank vent cured the problem.

Sent from my SAMSUNG-SM-N900A using Tapatalk

 

[MADMAT]

Yep some say they can't tell I can tell instantly....

 

[Big Kahuna]

Check for your fuel lines sucking air, I had this happen a few years back, Tricky was helping me and after swapping carps, everything we could think of, he was riding with the hood off and noticed air bubbles running through the fuel lines. Only good thing about those stupid blue transparent fuel lines.

 

[Nate_D]

Same issue for me with the tank vent. Stuck closed. Carbs would pull fuel until the vacuum in the tank became too much. Let it sit for a bit and the vacuum dissipates and it would run for a few minutes, then shut down. I was chasing ghosts in the electrical system. I could smell fuel and I would hear a hiss when opening the gas cap, so I assumed the tank was pressurizing and all was well with the fuel system.


Sent from my iPhone using Tapatalk

 

[rubbertoe]

Just a suggestion here but check the water flow control valve on the pipe since its new .i accidentally closed mine too far and the ski ran like poop ! couldn't believe how much it choked the thing out ,steam i guess ? idk .something to look at . what return jet are you running in those carbs ?

 

[speedysprocket]

Same issue for me with the tank vent. Stuck closed. Carbs would pull fuel until the vacuum in the tank became too much. Let it sit for a bit and the vacuum dissipates and it would run for a few minutes, then shut down. I was chasing ghosts in the electrical system. I could smell fuel and I would hear a hiss when opening the gas cap, so I assumed the tank was pressurizing and all was well with the fuel system.


Sent from my iPhone using Tapatalk

I don't get this. Everyone preaches that you need the vent so that it doesn't let air out and pressurizes the tank. Wouldn't being stuck closed have the same result? If the tank is always making pressure, no air can flow in anyways.
I'm just glad I drilled my vent out and never have to worry about such a stupid problem.

 

[Blue]

Its a vent it holds pressure but as fuel goes out it vents air in to displace the fuel that is being used. Most think it vents out but it doesnt.

Sent from my SAMSUNG-SM-N900A using Tapatalk

 

[WILKEY]

Thanks guys will check all of this. I know the tank stays pressureized cause it makes a noise when you take the cap off

 

[speedysprocket]

Its a vent it holds pressure but as fuel goes out it vents air in to displace the fuel that is being used. Most think it vents out but it doesnt.

Sent from my SAMSUNG-SM-N900A using Tapatalk

If air is ever going to go into the tank through the vent, it would mean the tank has drawn a vacuum, which would mean it wasn't pressurized at that time.

Like any fluid, gasoline is going to vaporize. There is a max pressure where this vaporization will stop and maintain at though- vapor pressure. The pressure in the tank should consistantly be this vaporization pressure as gas will constantly vaporize as we use fuel (sloshing around caused by riding helps this) if air isn't allowed to escape. However, what will change this pressure is temperature. Take your red gas can with cap on it out of your cool garage and leave it in the back of your SUV on a summer day. It looks like a balloon when you get back. Vent it and put the cap back in your cool garage. Next day it'll be shriveled up like a prune. This reason, among others, is why I don't believe in the tank pressurization theory. Vent your tank to atmosphere and jet accordingly, because atmosphere is what your popoff and jets all work off of, not some temperature dependent vapor pressure of gasoline.

Now, Wilkey- take your vent off and come ride after work today (surf forecasted!). It may not be tuned perfect, but if you ride without issues, we found your problem. If it's still there, then maybe we chase the coil.

 

[Jetfiend]

I don't get this. Everyone preaches that you need the vent so that it doesn't let air out and pressurizes the tank. Wouldn't being stuck closed have the same result? If the tank is always making pressure, no air can flow in anyways.
I'm just glad I drilled my vent out and never have to worry about such a stupid problem.

So you drilled out the check valve? Or are you just running a straight line out of the fuel tank?

 

[speedysprocket]

Initially, my Octane, which is where I started, had a valve that vented outside the hull to relieve pressure (which I think was clogged), and one inside the hull to allow pressure in. I got rid of the out vent and just drilled the in vent with the smallest bit I had.

 

[augustaf]

fuel filter may be restricted

 

[Half flip95]

I had this same problem last season. Good luck. I couldn't figure it out. Did all aforementioned things 10x over

 

[Pro-pulsion]

Tank vents for sure can make this happen, I had it happen on a Kawi many years ago. With the Kawi though it would implode the tank, when you pop the engine cover off the tank was all sucked in until enough air could squeak in to let the ski run for a few seconds more. I had to drill a tiny pin hole through the tank vent and it was fine after that. Two other areas that might be something to consider are amount of air coming into the engine compartment. If you are running a smaller AM hood and a big bore air glutton you might not be feeding it enough air to keep it running. The only other thing that comes to mind is a possible exhaust leak filling the engine compartment with enough exhaust emissions to snuff out the engine. That happened to an older Honda outboard motor my buddy worked on. 3 different shops couldn't figure it out, with the engine cover on it would die in 20 seconds or so, with it off, it would run a full tank through. I don't quite remember where it was leaking from but it seems to me that it was around the manifold.

 

[AZRIDER]

water back flowing up theexhaust? is your exhaust outlet at all modified?
ive seen hot pipes cause this problem too, but the tank issues seems like the easiest to eliminate first
i have dealt with this issue being caused by exhaust being loosed into the hull myself, but dam is that obvious when you open the hood