Backflip bogging problem

[tipafew]

My buddy is having issues with his DVX. Ski has a PHP 1015, PFP, Total loss, 48 novi's, Kart Tank.

When doing multiple flips in a row, every single time on the third trick the ski will bog really bad. Immediately runs fine again after that and will consistently do the same thing every time. This is a new issue out of the blue that started a couple of weeks ago.

Last weekend we noticed some stuff in the fuel filters. I pulled the carbs apart and cleaned them. Cleaned out all of the lines. Cleaned the tank. Replaced filters. One of the internal carb filters was about half full of the crap I that was in the inline filters. Felt confident it was solved.

Went out the the lake yesterday and it ran fine for a tank or so then started to do the same thing. We put some fuel in it and it seemed fine for a while again and did the same thing again.
I thought about tank vent, but I don't think that's it. It's one of those vented caps so it's a little hard to tell and I don't have another cap to try.
When we run WOT for a few seconds it seems fine but as soon as you start doing tricks it comes back again. Could fuel lines be picking up air while doing the flips???

Any thoughts??

 

[orangefinger]

are the fuel lines stationary in bottom of tank or weighted dangling lines ?

dirt in tank and in fuel filters must have come from where.. ?? In tank loose debris ? more filters ?\

tank vent is working properly ?

 

[SmittySX]

I’d give Zach a call

 

[tipafew]

are the fuel lines stationary in bottom of tank or weighted dangling lines ?

dirt in tank and in fuel filters must have come from where.. ?? In tank loose debris ? more filters ?\

tank vent is working properly ?

It has the dangling lines with weights.

I cleaned the tank really well. Have no idea where the debris came from. Almost looked like tiny cardboard fragments. Using a filter when filling the tank now and the inline filters look clear yet.

 

[orangefinger]

ok are the line inside the tank hard and don't bend anymore ?

does all this happen with empty or full tank ?

membranes ok not leaking ?

 

[tipafew]

ok are the line inside the tank hard and don't bend anymore ?

does all this happen with empty or full tank ?

membranes ok not leaking ?

 

[tipafew]

Talking to my buddy tonight he had one of the internal tank lines fall off a couple weeks ago before this started. He did shorten the lines a little at that time. I didn't realize this.
When I was cleaning the tank I noticed that the internal lines were barely staying attached so I switched them with new tygon lines. The lines still seem plenty long and they loop way around and lay flat in the tank. Could he have affected something when he shortened them??

 

[ProSouth]

I’d immediately go to the one way valve. I had a kart tank doing the same thing (not on 3 trick combos, I can’t even do one) Any time the ski was upside down it bogged 4-5 seconds and cleared up.
Second would be blowing out lines and replacing filters
Also check carb filters in the inlet since you had some tank debris
We (in our group) also had a kart tank with a poopty cap that wouldn’t allow it to pressurize. We put tape around the threads and tightened it to get it to act right.
Good luck

 

[Harbor]

If nothing is found you might pressure test the Pf chamber as well

 

[tipafew]

If nothing is found you might pressure test the Pf chamber as well

That's always a consideration but we had a bad chamber on this ski before and it didn't really do this. Of course the location of a crack could be different with different results. It was a new chamber last year though so no my first thought.

 

[tipafew]

I’d immediately go to the one way valve. I had a kart tank doing the same thing (not on 3 trick combos, I can’t even do one) Any time the ski was upside down it bogged 4-5 seconds and cleared up.
Second would be blowing out lines and replacing filters
Also check carb filters in the inlet since you had some tank debris
We (in our group) also had a kart tank with a poopty cap that wouldn’t allow it to pressurize. We put tape around the threads and tightened it to get it to act right.
Good luck

I think I might just swap tanks with another ski to eliminate fuel pick up and venting as possible issues. Seems like a good start to at least know if it tank related.

 

[Big Kahuna]

Might want to consider Needle & Seats, and Spring. Needle could be partially sticking or if spring is weak by the 3rd flip it could be letting the needle open......... Far Fetched but possible.

 

[tipafew]

Might want to consider Needle & Seats, and Spring. Needle could be partially sticking or if spring is weak by the 3rd flip it could be letting the needle open......... Far Fetched but possible.

I had it all apart and everything looked really good but I think I am going to pull it apart one more time for a good look.

 

[clouse22]

Any resolution to this??

 

[tipafew]

Any resolution to this??

I went through carbs and fuel system a second time. I switched his tank with his other ski at the same time and all seems good now. We ran a few tanks this week and she is ripping. I am thinking it was either a issue with the cap not venting or his pick ups for some reason.