Fuel sloshing in tanks

[Unchained]

I don't know if there's a solution to this when using gunnel tanks but I have been plagued by this on the last couple boats.
After a hard run you're decellerating and the fuel sloshes to the front of the tank and uncovers the fuel line at the back of the tank. Then the motor either shuts off or runs like crap for a minute until the air gets out of the line.
My Russell fuel tanks have some baffles in them but evidently not enough.
I really can't think of any solution other than cutting the tanks apart and putting some trap doors over the holes in the baffles. Something like an oil pan has.
On the last boat I had a spacer under the front tank mount to try to have a downhill angle to the rear. Didn't help much.
I have to believe this is a common problem.

[ck7684]

Good question, you'd think somebody would make a decently baffeled tank. I've had this happen before as well...

[502 JET]

Are you positive that's whats happening? Did you see your fuel pressure drop when this happens? Does it happen when the tanks are full? It shouldn't, if it gives these same symptoms with full tanks and no pressure drop then look elsewhere.

[Fiat48]

This may not relate but here goes:
I did a blown injected gas deal with 2 Russell side tanks. I welded a bung at the bottom lower rear of the tank. The thing would lose prime unless the tanks were absolutely full on shutdown.
I removed the rear fitting and welded in a long tube into the fitting about 18" long...making the fuel pickup toward the middle of the tank. That fixed it.
I think I used 1/2" aluminum tubing as I remember.

[DMOORE]

A much easier fix, rather than cutting the tankes apart, would be to run a small fuel accumulator tank. From the main tanks, run the lines into a single 1/2 gallon aluminum tank that the system will feed from. This way you will always have a small "reserve" if the fuel sloshes forward. A polished setup could look very clean and trick.
Darrell.

[ck7684]

Another good idea...I know mine was just fuel sloshing away from the pickup cuz it would die during hard turns when the tanks were getting low, but never when full...it was a different boat than I have now tho...

[HONDOG]

A much easier fix, rather than cutting the tankes apart, would be to run a small fuel accumulator tank. From the main tanks, run the lines into a single 1/2 gallon aluminum tank that the system will feed from. This way you will always have a small "reserve" if the fuel sloshes forward. A polished setup could look very clean and trick.
Darrell.
I run out of my gunnel tanks into a 4 gal. IMCO with overflow fittings in the ends which return to the gunnel tanks. I feed my engine from the IMCO. This system is working great so far.

[Unchained]

Thanks for the feed back.
The accumulator tank has some merits. I'l have to ponder on that one, I don't want to sacrifice any interior room.
Installing a long pickup tube angling toward the front may be possible and easy to try too. Even moving the pickup 12" or 18" forward would help.
I am probably going to cut these tanks at the end of the season anyways. They are way too large for what I need. I've got 48 gal of capacity and 30 would be plenty. With the jet boat I had 16 gal of total capacity and that was marginal.
A shorter tank would lessen the fuel sloshing problem.

[cfm]

A much easier fix, rather than cutting the tankes apart, would be to run a small fuel accumulator tank. From the main tanks, run the lines into a single 1/2 gallon aluminum tank that the system will feed from. This way you will always have a small "reserve" if the fuel sloshes forward. A polished setup could look very clean and trick.
Darrell.
Definately. Most call them fuel surge tanks. Just type this in to your search engine and many will come up. Be careful, many are Australian shops. LOL.
As an example (I don't know of them) A quick search landed me this:
http://www.speedmachineperformance.com/ProductDetails.asp?ProductCode=SMP+Fuel+Surge+Tank

[Havasu Hangin']

Switch to carbs.
:jawdrop:

[Danhercules]

I have a buddy really into Motocross. He is making pipes and lots of other items. He told me a few weeks back about a foam in the fuel tanks to prevent sloshing. Still holds lots of fuel. I will call him and see what I can find out.
I just talked to him. Here is a link. http://www.weaponmx.com/index.php?&page=products&a=Gzero&id=2
It takes up 1% of the volume of the tank and will prevent sloshing. I think this will work.

[DMOORE]

Definately. Most call them fuel surge tanks. Just type this in to your search engine and many will come up. Be careful, many are Australian shops. LOL.
As an example (I don't know of them) A quick search landed me this:
http://www.speedmachineperformance.com/ProductDetails.asp?ProductCode=SMP+Fuel+Surge+Tank
Thanks for the info. I wasn't sure of the name, but I have seen them in a number of boats.
Darrell.

[thatguy]

Fuel cells for drag cars have used the "foam" for years, it actually looks more like the stuff on the pad you clean your barbque grill with.
I have wondered for a long time why boats don't use cells. Is it because most cells are plastic?
Tommy

[UBFJ #454]

We run a fuel cell with foam inserts ... pretty common in drag boats these days.
If your going to cut the tanks open over the winter anyway, put fuel cell foam in rather than baffles ... it will cut the total volume down somewhat, but, worth it in terms of sloshing and Safety.

[Unchained]

Thanks for the input
I knew I'd get some good ideas on here. :idea:
The foam inserts sounds like the best way to go.
Now if I could just figure out how to get it in there w/o cutting the tanks open.
I do have an opening where the fuel level gauge was that I'm using for a return line fitting. That's about 2.25"
?? Switch back to carbs ?? Yeah, that's going to happen :D

[Danhercules]

I have a buddy really into Motocross. He is making pipes and lots of other items. He told me a few weeks back about a foam in the fuel tanks to prevent sloshing. Still holds lots of fuel. I will call him and see what I can find out.
I just talked to him. Here is a link. http://www.weaponmx.com/index.php?&page=products&a=Gzero&id=2
It takes up 1% of the volume of the tank and will prevent sloshing. I think this will work.
This foam can be installed with out cutting the tanks open.

[cyclone]

I don't know if there's a solution to this when using gunnel tanks but I have been plagued by this on the last couple boats.
After a hard run you're decellerating and the fuel sloshes to the front of the tank and uncovers the fuel line at the back of the tank. Then the motor either shuts off or runs like crap for a minute until the air gets out of the line.
My Russell fuel tanks have some baffles in them but evidently not enough.
I really can't think of any solution other than cutting the tanks apart and putting some trap doors over the holes in the baffles. Something like an oil pan has.
On the last boat I had a spacer under the front tank mount to try to have a downhill angle to the rear. Didn't help much.
I have to believe this is a common problem.
i have this problem with the tanks are almost empty. can't make any hard passes when i'm down to the last few gallons or the fuel pressure drops when i slow down. keeps me from running out of gas because as soon as i see the fuel pressure gauge on the dash fluctuate i know its time to head back to camp.............
a surge tank will fix it.
the foam will fix it.
the pick up line will fix it.
all good ideas.
my fuel cell that i run at the track has the foam. the fuel cell in my old offroad truck had the foam. i'd try the foam if you can squeeze it in there.

[IMPATIENT 1]

Switch to carbs.
:jawdrop:
lol, he needs some good ole quadrajets on it!:D :D :D :D :D

[Unchained]

Thanks for that link Dan.
I'll check into the foam.
I have to address this ASAP because losing power at high speed may leave a spot on the front seat. :eek:

[Danhercules]

Thanks for that link Dan.
I'll check into the foam.
I have to address this ASAP because losing power at high speed may leave a spot on the front seat. :eek:
did ya get my pm?