Shop Discount Sea-Doo Parts

Gas evaporated?

Messages
9
Likes
0
Water Crafts
98 GTX Limited
97 XP
#1
I have a 97 xp and it's never been in water since I've had it ( 2 years). I put 2 or 3 gallons fuel in it ( I got it empty) , got it running and left it outside in Florida sun for 2 or 3 months. When I pulled it into my garage the tank was bone dry.... thought I had a leak for sure. Ive read about these tanks leaking through a defect or drive shaft rubbing it. Pulled motor to get tank out and filled it with water, but 2 days later, not a drip. Is it possible that every drop evaporated out? Anyone else have this happen? Good thing is upon removal of everything I found a lot of things need replacing and gas tank had lots of crud in it. Thanks in advance.
 


Messages
137
Likes
18
Location
CO
Water Crafts
95 XP720 +3mm Bore
95 GTX657x +1mm Bore
#2
that's an extremely odd situation. Generally, when gas evaporates it will leave behind several additives these will often be in the form of a liquid or a residue.

maybe some punk siphoned it?
 
Last edited:

statikuz

Active Member
Messages
156
Likes
12
Location
Nevada
Water Crafts
2002/2003 RX DI
#3
I can't believe it evaporating that fast. Maybe in a wide open container in the sun. But not in a tank with no real airflow.
 
Messages
122
Likes
10
Location
central florida
Water Crafts
1998 Sea Doo XP Limited
2000 Kawasaki Ultra 150
#4
that's an extremely odd situation. Generally, when gas evaporates it will leave behind several additives these will often be in the form of a liquid or a residue.

maybe some punk siphoned it>?
I think Nick might be right. Unless the cap was left off, you may have been relieved of your gas by someone. I don't know if even a stuck open check valve would allow it to evaporate like that.
Set a trap... leave the water in and see if it gets siphoned again.

You could try a pressure test on your fuel system and see if there is a stuck check valve on the vent side. It happened on my 98'. Everytime I would fill it up, it would piss gas out the through hull vent. My fuel cap quit sealing all the way too. It wouldn't tighten enough to seal. I greased the threads and that fixed it. I can't remember, but I think I doubled the oring too.
I didn't notice a gas loss, but I keep it in a garage out of the sun.
 
Messages
122
Likes
10
Location
central florida
Water Crafts
1998 Sea Doo XP Limited
2000 Kawasaki Ultra 150
#5
If you have trouble getting your fuel tank straps back in, let me know. Or checkout a post I did on pwctoday about it. Its titled "1998 sea doo xp limited install fuel tank straps"
On mine it was near impossible until I rigged up a tool.
 
Last edited:

GGuillot

Well-Known Member
Messages
878
Likes
130
Location
Alabama
Water Crafts
1997 GTX
1996 GSX
#6
I have a 97 xp and it's never been in water since I've had it ( 2 years). I put 2 or 3 gallons fuel in it ( I got it empty) , got it running and left it outside in Florida sun for 2 or 3 months. When I pulled it into my garage the tank was bone dry.... thought I had a leak for sure. Ive read about these tanks leaking through a defect or drive shaft rubbing it. Pulled motor to get tank out and filled it with water, but 2 days later, not a drip. Is it possible that every drop evaporated out? Anyone else have this happen? Good thing is upon removal of everything I found a lot of things need replacing and gas tank had lots of crud in it. Thanks in advance.
There's no way 2 or 3 gallons within 2 or 3 months completely evaporated out. I've seen it reported on the FB forum I'm on, there's lowlife people out there stealing gas all the time... Some people purposely leave only a couple gallons in it for this reason when they leave it outside.
 

mikidymac

Moderator
Staff member
Moderator
Messages
12,096
Likes
1,191
Location
California
Water Crafts
2003 GTI
2001 XP
1996 XP
1996 HX
1991 Superjet
2001 Superjet
#8
If the cap was on and the system closed it isn't possible.
 
Messages
122
Likes
10
Location
central florida
Water Crafts
1998 Sea Doo XP Limited
2000 Kawasaki Ultra 150
#9
After some thought, I'm starting to consider it could have evaporated. A plastic gas can will expand like a beach ball (almost) if left in the back of my van for a short time. If the tank was constantly vented due to a failure somewhere in the system, maybe it could have happened. Gas does evaporate pretty quickly. If someone siphoned the gas, they wouldn't have gotten every drop. Maybe they siphoned some and the rest evaporated.
So here are some pics of three possible ways the gas could evaporate and escape.

pic# 1: notice the gas cap o-ring doesn't seal against the fuel filler neck. Look at the gap in the pic. The clutch in the gas cap slips before my cap tightens all the way down. I never knew it wasn't sealing until I did a pressure test when I was chasing the air bubbles in the fuel line gremlin. I had greased it before to make it thread in further, but that washes off after a few fill ups.

gas cap.jpg

pic#2: the fuel tank vent check valve. It can stick open and constantly vent the tank to atmosphere. Its the blue check valve in the blue line.

fuel tank vent check valve.jpg

Pic #3: The breather check valve that allows air to enter the fuel tank as gas is used by the engine. That could stick open too. Its the one in the gray line. Yeah, the gray line. That's the only place on the boat that still has it (from the "Y" connector up to the breather vent under the seat). Its a pain to cut that stuff off the fittings so I have procrastinated on doing it.

fuel tank inlet check valve.jpg

So, if your gas tank dried up, you might want to check these. It wouldn't be a waste of time because if one of them is bad maybe you can lose some gas. For sure though, you can get water in to the tank if the boat gets flipped.
 

JJinSC

Well-Known Member
Messages
1,275
Likes
33
Location
SC
Water Crafts
1997 Sea-doo XP
#10
I do not believe that that much gas has evaporated in that amount of time even with those conditions and with only 2 or 3 gallons in a 15 gallon tank, I don't think it would have been pressured out of your vent either. I have only seen that happen with a full tank. If your needle and seats are leaking a good amount could be in your engine, but not that much.
 
Messages
122
Likes
10
Location
central florida
Water Crafts
1998 Sea Doo XP Limited
2000 Kawasaki Ultra 150
#11
I do not believe that that much gas has evaporated in that amount of time even with those conditions and with only 2 or 3 gallons in a 15 gallon tank, I don't think it would have been pressured out of your vent either. I have only seen that happen with a full tank. If your needle and seats are leaking a good amount could be in your engine, but not that much.
In an airtight fuel system, the pressure relief valve releases at 1.5 PSI. With the right amount of heat build up it would release long enough to vent the extra pressure. However, if that relief valve is stuck open and freely allowing the tank to vent, evaporation would occur. How much? Without actually testing it, who knows. The OP said the tank was bone dry, so the gas or remaining gas if siphoned, had to go somewhere.
In that case where you saw it happen with a full tank, was it vapor loss or was it liquid gas pissing out the side?
 
Messages
48
Likes
2
Location
Texas
Water Crafts
1997 SeaDoo GTI 720
1998 Lavey Craft Sebring 20.2 with 200 Mercury
#12
once I left the fuel valve on in the hot sun. I think the pressure in tank force fuel to move....engine was FULL OF FUEL and this was about 1 hour. Sea Doo was in the driveway.
 

mikidymac

Moderator
Staff member
Moderator
Messages
12,096
Likes
1,191
Location
California
Water Crafts
2003 GTI
2001 XP
1996 XP
1996 HX
1991 Superjet
2001 Superjet
#13
In an airtight fuel system, the pressure relief valve releases at 1.5 PSI. With the right amount of heat build up it would release long enough to vent the extra pressure. However, if that relief valve is stuck open and freely allowing the tank to vent, evaporation would occur. How much? Without actually testing it, who knows. The OP said the tank was bone dry, so the gas or remaining gas if siphoned, had to go somewhere.
In that case where you saw it happen with a full tank, was it vapor loss or was it liquid gas pissing out the side?
My ski boat had a full tank of gas and has an open vent hose for the tank. It sat for 6 years because of family and life issues and the tank was still full to the top when I drained it to put fresh gas in. You just are not going to get the OP's loss from evaporation in a basically closed system.

I think this will just go down as a mystery to all of us.
 

mikidymac

Moderator
Staff member
Moderator
Messages
12,096
Likes
1,191
Location
California
Water Crafts
2003 GTI
2001 XP
1996 XP
1996 HX
1991 Superjet
2001 Superjet
#14
once I left the fuel valve on in the hot sun. I think the pressure in tank force fuel to move....engine was FULL OF FUEL and this was about 1 hour. Sea Doo was in the driveway.
If that is the case, either your tank pressure relief valve is not functioning or your needle and seats are bad in the carb. Leaving the valve on should never flood the engine.
 
Messages
48
Likes
2
Location
Texas
Water Crafts
1997 SeaDoo GTI 720
1998 Lavey Craft Sebring 20.2 with 200 Mercury
#15
If that is the case, either your tank pressure relief valve is not functioning or your needle and seats are bad in the carb. Leaving the valve on should never flood the engine.
this was before the rebuild and that makes sense
 

JJinSC

Well-Known Member
Messages
1,275
Likes
33
Location
SC
Water Crafts
1997 Sea-doo XP
#16
I do not believe that that much gas has evaporated in that amount of time even with those conditions and with only 2 or 3 gallons in a 15 gallon tank, I don't think it would have been pressured out of your vent either. I have only seen that happen with a full tank. If your needle and seats are leaking a good amount could be in your engine, but not that much.
Clarification here. While I state I saw it with a full tank, I meant that I have seen gas come out of the inlet vent (not functioning properly) enough to see gas run down the side of the hull due to expansion of gas in a full tank. I did not mean pissing it out and by no means emptying the tank.
 
Messages
122
Likes
10
Location
central florida
Water Crafts
1998 Sea Doo XP Limited
2000 Kawasaki Ultra 150
#17
Mine would piss out onto the ground at the gas station when i filled it up high enough to see gas in the filler neck. If i started the engine, it would stop pissing. I guess the slight vacuum of starting the engine would pull the check valve closed again. After replacing the check valve it didn't do it anymore.
Edit: after thinking about it, starting the engine wasnt pulling the check valve closed. The check valve was stuck open. It was just breaking the siphon created by the gas flowing freely out of the vent.
 
Last edited:
Messages
9
Likes
0
Water Crafts
98 GTX Limited
97 XP
#18
Thanks for all the input! I still dont know why it was bone dry. I took the water out and put a few gallons of gas in it with only the vent open and after a few days level is the same. I've since drained it and will just put it all back . I'm replacing all the grey fuel lines, there is so much crap in the selector switch its unbelievable. In a week or 2 it'll be done and water ready but I'm still wondering about the gas disappearing and not a drop left..... thanks again for all the input!
 

mikidymac

Moderator
Staff member
Moderator
Messages
12,096
Likes
1,191
Location
California
Water Crafts
2003 GTI
2001 XP
1996 XP
1996 HX
1991 Superjet
2001 Superjet
#19
Did you accidently use one of these cursed gas caps? I think I found the culprit.
gremlin.jpg
 

gazzaskirepair

Active Member
Messages
350
Likes
36
Water Crafts
RXT. RXT IS SPEEDSTER 2006 REPAIR SEADOOS WEEKLY FOR CUSTOMERS
#20
If you have trouble getting your fuel tank straps back in, let me know. Or checkout a post I did on pwctoday about it. Its titled "1998 sea doo xp limited install fuel tank straps"
On mine it was near impossible until I rigged up a tool.
Can’t find your post strap installation
 

SPONSORED LINKS

Usergroup

Administrator Moderator Premium Member
Top