27 gallon gas tank install on 16 SC

[Fisherdv]

What would be the safest, and cleanest way to drill out the vent hole? Thick grease on the drill bit to catch the shavings, kinda like chasing a threads in an engine block? Thank you guys for your patience on this :bowdown:

[blindmonkey]

Try making the vent hose as vertical as possible first so no low areas exist first as per 3weights suggestion. From the photo posted it looks like it has extra length that is causing low spots near the tank which would hold gas and restrict air flow.  Mine is almost vertical.

[Fisherdv]

Try making the vent hose as vertical as possible first so no low areas exist first as per 3weights suggestion. From the photo posted it looks like it has extra length that is causing low spots near the tank which would hold gas and restrict air flow.  Mine is almost vertical.

I did cut some length off of the vent hose to make it more straight and didnt help

[croaker stroker]

Drill motors make sparks.

[Fisherdv]

Yeah I thought about the drill making sparks to, probably not a good idea. I measured the vent hole coming off of the tank and it is only a quarter inch inner diameter going to a five eights inner diameter hose. I don't think it's the vent P-trap because I can blow through it with no problem

[croaker stroker]

Yeah I thought about the drill making sparks to, probably not a good idea. I measured the vent hole coming off of the tank and it is only a quarter inch inner diameter going to a five eights inner diameter hose. I don't think it's the vent P-trap because I can blow through it with no problem

But you are blowing through it when it is dry. I think when gas burps up into the p-trap it may be designed to shut.

Your tank fills fast with the vent open.  If you called the tank manufacturer, they could tell you if 1/4" vent is adequate.

[Fisherdv]

 Do you think if I try to fill up with the P-trap disconnected from the hose that I'll get gas squirting out of that open hose?

[croaker stroker]

Do you think if I try to fill up with the P-trap disconnected from the hose that I'll get gas squirting out of that open hose?

I don't know. Probably only when your tank is full.

All of the earlier boats had tanks vented in this way. Just a hose overboard, or into the motor well, and a chrome scoop to prevent water intrusion.

[croaker stroker]

...  actually, yours looks designed to prevent water intrusion. (Instead of a loop in your vent line). Looks restrictive ?

I am not sold on those new fangled contraptions.   :hoboy:
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[Fisherdv]

Yeah I think all the EPA stuff has really gone too far. If you look at the EPA portable tanks they don't vent into the atmosphere but when you open the cap you get like 10 times as much coming out all at once how does that save the atmosphere? And if the P-trap vent that I have is supposed to save the atmosphere how does that help when I'm spilling gallons of fuel on the ground while filling?  :hoboy: I can only imagine the set ups that vent into the charcoal canister's

[AJFishin]

It looks to me like your fuel tank vent is smaller then what the guidelines say it should be.
Your fuel tank vent looks to be about a 1/4". Have you measured it?
I think what Danno said on pg 5 is right about the factory not measuring the thickness of that tank vent.

From the USCG regarding the size of fuel tank vents:



Here's a link for the USCG, page 34.
http://www.uscgboating.org/assets/1/AssetManager/ABYC.1002.01.pdf

Here's another link outlining the ID of a boats fuel tank vents:
https://www.boatsafetyscheme.org/boat-examination/non-private-boats/part-2-inboard-engines/vent-pipes/

[Fisherdv]

It looks to me like your fuel tank vent is smaller then what the guidelines say it should be.
Your fuel tank vent looks to be about a 1/4". Have you measured it?
I think what Danno said on pg 5 is right about the factory not measuring the thickness of that tank vent.

From the USCG regarding the size of fuel tank vents:



Here's a link for the USCG, page 34.
http://www.uscgboating.org/assets/1/AssetManager/ABYC.1002.01.pdf

Here's another link outlining the ID of a boats fuel tank vents:
https://www.boatsafetyscheme.org/boat-examination/non-private-boats/part-2-inboard-engines/vent-pipes/

AJFishin, that's it! Good find! That article says 9/16, with a MINIMUM 7/16 ID vent hole. Mine is 1/4, which is 4/16, half the size of what's called for according to that write up. I suspected that vent hole was too small

[Fisherdv]

 That would also explain why fuel was squirting (as if under pressure) from the tank vent with the hose removed. I can see splashing , but it was squirting. Vent too small, to much pressure build up

[Yachter Yat]

   Fisher: CAUTION:  HEED CROAKER'S WARNING!   DO NOT drill that tank with an electrically powered device!   Find a hand ream, or something similar.  You won't be able to get on-line service to this site when you're sitting on the Moon.  :hoboy:

Yat

[Fisherdv]

Yes Yat, the 4th of July is over and I will NOT use a power drill, or a vacuum. So how do I tap that hole without getting  large twists of plastic in the tank that could block a fuel line?

[Yachter Yat]

   I'll have to work on that, but I think a drill bit (being turned by hand) should be able to cut through that plastic.  You'd have to get creative with finding a way to attach something to the bit that would give you enough leverage in order to twist it. Problem is, there's not a lot of room in there.  Course, that doesn't solve the problem relating to the plastic debris.  Guess I'll have to look around the garage.

Yat

[Fisherdv]

I can get a hand drill that has a handle to turn for leverage or a T handle style ream. I'm thinking maybe put grease or thick oil on the drill bit to catch the plastic shavings what do you think

[Rokefin]

If it is indeed a bad design the manufacturer should replace your tank. I would get a hold of the manufacturer and open the discussion with them.  Looks like the vent is too small, as previously mentioned if you open it up do not make the nipple too thin.....again, I would get a hold of the manufacturer.   

[Danno]

I can get a hand drill that has a handle to turn for leverage or a T handle style ream. I'm thinking maybe put grease or thick oil on the drill bit to catch the plastic shavings what do you think

Yep, use  a T-handle similar to those used for taps.

When turning by hand, you're not likely to get the small particles generated by a high speed drill. The plastic is relatively soft as well so it will cut easily and create the typical long spiral pieces. I like the idea of using grease on the drill bit to get everything possible to stick to it.

[Yachter Yat]

   The fuel fill hose might be a little close for anything too long.  Perhaps you could attach a ratcheting driver handle? 

Yat

[Fisherdv]

If it is indeed a bad design the manufacturer should replace your tank. I would get a hold of the manufacturer and open the discussion with them.  Looks like the vent is too small, as previously mentioned if you open it up do not make the nipple too thin.....again, I would get a hold of the manufacturer.   

I think that would be my best option before I do any modifications to the tank.

[croaker stroker]

If it is indeed a bad design the manufacturer should replace your tank. I would get a hold of the manufacturer and open the discussion with them.  Looks like the vent is too small, as previously mentioned if you open it up do not make the nipple too thin.....again, I would get a hold of the manufacturer.

+1

[Rokefin]

I'm sure Don will get you squared away.....but another thought I had was possibly a tee off your vent nipple and running 2 vent lines - possibly may give enough venting to allow normal fill operations.

[Fisherdv]

I'm sure Don will get you squared away.....but another thought I had was possibly a tee off your vent nipple and running 2 vent lines - possibly may give enough venting to allow normal fill operations.

It's the vent nipple itself that's too small

[Rokefin]

Yes, I did realize the vent was too small, my thought was an extra line might allow it to breathe enough but I guess being restricted at the vent nipple itself not much will help.
I am curious looking at the engineering part of this why/how did they come up with such a small diameter nipple