whizzy

i have recently built a blastcat with a sikk 27cc engine and have put 2 small s391 530cc fuel tanks by sullivan at the front of the boat what seems to be happening is that when running full throttle it accelrates quickly but then in middle of high speed run it bogs down we came up with fuel starvation but werent sure and was wondering if anyone has any ideas how to solve this

thanks in advance for any help or advice you can give

saleens7

do gas engines use exhaust pressure to pump fuel to the engine??

if they do...you could have a loose fitting for the pressure line and not enough fuel is getting ot the engine.....

same thing is happening to my SW (nitro)...

whizzy

no they dont work in the same way as the 1/5th scale fgs but i was wondering would it be caused by using the 2 tanks and would turning one round help or would the fuel bag be a better idea altogether and does the fuel bag have to lie flat or can it lie over the tunnel on the blast cat not clued up on the bags if i was gonna go that road so would need some help on installation and general advice about them

Ron Olson

My Feedback: (1)

The problem could be that you are using two tanks. With the nitro boats, you have the pressure form the pipe to help push the fuel from one tank to another. In gas boats you don't have this feature as the pump on the carb is drawing the fuel making it hard to pull gas from the 2nd tank.

whizzy

so would the iv fuel bag resolve that im possibly looking at the big fuel bag and how do u fill these fuel bags too

BMAD01

Ron, I'm going to be running 2, 8oz Dubro tanks in my new Rigger I'm setting up since I can't squeeze a 500ml bag up front. The tank on the left is the secondary tank. The long line with the plug is the filler tube. The open tube is the vent. and the line on the right is the jumper line to the primary tank which only has a fuel out tube. This is the way I was shown to hook up dual tanks by an old nitro guy I run with. Sure hope it works!! LOL But Bob English (the guy who built the hull) also runs 2, 8oz tanks in his. I just got back from running my Blast Cat. Have'nt even cleaned it up, I just took a pic. I'm running a 500ml bag in the right sponson (pic) which works like a million bucks! Brian

Ron Olson

My Feedback: (1)

You can either use a 500ml or 1000ml bag but it's your choice. Some bags are better than others, the Baxter brand seems to be one of the better ones.
you fill these through the fuel line to the carb then get the air out. the bag will collapse as it empties.
Keep fuel in the bag at all times once you've filled it for the first time otherwise it can dry out and crack if you don't.
This site will give you an idea of how to set one up, http://www.americanrcboats.com/produ...elingparts.htm

Ron Olson

My Feedback: (1)

Zac does have some 250ml bags but I don't think that it would carry enough gas for you as it's only a little over 8 ounces.

Paul M

I was having the same problems until I went to IV bags. No problem now. You just have to be sure to burp the air out. Also, you will have no hint when the tank is running dry. It will just die.

Ron Olson

My Feedback: (1)

I'm doing a search right now on IV bags. go to the bottom where it says "Search this thread" and put "IV bags" in there, I've found 3 pages of info so far.

whizzy

thanks ron for your reply much appreciated as well as all the others looks like the iv bag is the way to go

Flabum

What size fuel line are you using? And is the first tank vented?

BMAD01

Yes Flabum, The first tank is vented. The stoppers are drilled out, and I'm using 5/32" lines. I'm running Du-Bro X-Large Tygon fuel lines. Brian

skoda450

Whizzy,
I hope you are still here as I have some advice on IV bags.
They are great for tanks since they don't allow the fuel to foam up. They also don't have a vent which eliminated the constant smell of gas from the boat (wifes complaint, not mine!). They do have down sides as well. Gasoline is always evaporating and the bags, over time, will blow up and must be burped. They will also eventually get hard and need replacing but will last a year if kept full.

The filling system using a "T" fitting in the link is very messy with a bag tank. Because, when the bag is full it has developed pressure and will squirt out while you are trying to plug or unplug it with the stopper. The best system is a filler valve from Dubro made for gasoline. It is in the supply from the bag to the carb. When the filling probe is insereted, it opens the line from the filler to the tank and closes the line to the carb. Likewise, when the probe is removed it reconnects the tank to the carb line. They are 10 times the price of the "T" but well worth it. Make sure you get one for gasoline vice one for nitro fuel.

For more info check out this article in the third issue of ModelGasBoats.com

http://www.modelgasboats.com/home/html/gas_bags.html

tazmaniaboats

question to bmad 01
hello
i saw your photo of a rigger with azenoah and i would like more info
thankyou

Ron Olson

My Feedback: (1)

Warehouse Hobbies has just come out with a gas shut-off valve which looks like a good addition to any boat for when you store or transport it. I'm leery of storing my gas boat that I'm building in my basement because of the possible problem with fumes.

ROGER40

Hi,definetly go for the IV tank bags,once you get the hang of them,you will never go back to a normal tank,no petrol smells,no leaks,water cannot get in,flexibility in siting are just some of the advantages,just make sure you get all the air out of the bag and fuel line.

Cleggmeister

Martin, you got to the bottom of this yet mate? If all else fails you could try running with one pressurised tank (the other filled with water for balance). If this resolves your issues you'll know it's fuelling related and you can go for an IV bag.

I'll get to work on mine this Friday and will be running for Sunday.