New Thundercat (loss of power WOT?) - Page 2

Roflhat · 20 July 2017, 06:34

Does it run better with a bit of choke? If that's the case it's likely it's drawing air in somewhere it shouldn't be

watersidemat · 20 July 2017, 09:15

That's what I'm worried about.
I'm pulling the choke lever lol 3mm. Looking into the carb the choke butterfly doesn't move. Pull the choke all the way out it stalls (all at WOT)

Bigplumbs · 21 July 2017, 05:30

I bet the gasket on the carb fuel bulb is letting in air or you just have a fuel restriction somewhere between the tank and carb.

Dennis

watersidemat · 21 July 2017, 09:35

Carb fuel bowl? I have ordered a bunch of gaskets so I'll be putting them in to see.

Could be the fuel bladder. I don't know how the valve on the top works. Might try it on my old zapcat seeing as I still have it. I know that runs flawlessly so it will determine if it's the fuel bladder.

Bigplumbs · 21 July 2017, 14:52

Quote:

Originally Posted by watersidemat

Carb fuel bowl? I have ordered a bunch of gaskets so I'll be putting them in to see.

Could be the fuel bladder. I don't know how the valve on the top works. Might try it on my old zapcat seeing as I still have it. I know that runs flawlessly so it will determine if it's the fuel bladder.

Or better just connect the new engine to a normal fuel tank and see how that works

Dennis

watersidemat · 01 August 2017, 17:39

Tank seems to be the problem. Looked at the filter on the fuel bladder today and it was totally gummed up with stuff I don't know what it is but it builds up really quick. Just 10 mins on WOT and the engine starts to starve fuel so have to take the filter out and remove the gunk and it's back in buisness. I don't know if it's the bladder lining or something growing inside the bladder.

watersidemat · 01 August 2017, 17:40

watersidemat · 01 August 2017, 17:58

Jist emptied the bladder into a tank. Heres whats in the filter...

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Could it be the lining. I don't know much about these bladders.

Roflhat · 01 August 2017, 18:12

I've never run one of those tanks but I've spoken to folk who have and say they're more trouble than they're worth

watersidemat · 01 August 2017, 18:50

Posted it on one of the thundercat Facebook groups and there's a few comments already staring the lining is degrading. Sounds pretty terminal.

watersidemat · 18 August 2017, 10:26

Get no luck from these engines, having some odd engine troubles, hope someone can figure this out.
After running wide open throttle and reducing back down to idle, when I go to accelerate slowly from idle it stalls when the throttle reaches the dot on the grip, the point before the cam starts to open the carb butterflies. If I accelerate quickly past this point it's fine.

Second issue, half way through an outing I'll lose half of the power like im down on a cylinder and it will kick back in for 2 seconds then go back down. I'm getting some water in under the cowl and I'm thinking it might be getting into the carbs. There's a milky residue sat in the carb opening. There's condensation inside the carb throat and big droplets of water on the exterior of the carbs. Should the boat be throwing up a big plume of water?

Any help appreciated.

lukewhiting · 18 August 2017, 19:56

Quote:

Originally Posted by watersidemat

Get no luck from these engines, having some odd engine troubles, hope someone can figure this out.
After running wide open throttle and reducing back down to idle, when I go to accelerate slowly from idle it stalls when the throttle reaches the dot on the grip, the point before the cam starts to open the carb butterflies. If I accelerate quickly past this point it's fine.

Second issue, half way through an outing I'll lose half of the power like im down on a cylinder and it will kick back in for 2 seconds then go back down. I'm getting some water in under the cowl and I'm thinking it might be getting into the carbs. There's a milky residue sat in the carb opening. There's condensation inside the carb throat and big droplets of water on the exterior of the carbs. Should the boat be throwing up a big plume of water?

Any help appreciated.

I used sealant to block the drain holes in the base off the cowling which stopped the water getting in. My boat always kicked up a nice rooster tail when at speed

I think I had similar issues to you with power loss. I never really got to the bottom of it but it was always better after I rebuild and reset all the carbs.

Check other things like fuel lines & connections. Old lines can cause some issues is an easy fix.