Fuel cell plumbing issue (tank pressurizes)

[robselina]

Okay, I've got a summit fuel cell part # SUM-290114

http://store.summitracing.com/partdetail.asp?autofilter=1&Ntt=SUM%2D290114&N=0&part=SUM%2D290114&autoview=sku&Ntk=KeywordSearch

I have it mounted in the back bed, I'm using the stock fuel line and return that went to the stock tank. Problem I'm having is that the tank is pressurizing when wheeling. It'll get bad enough that it'll stall out the rig if I don't pull the cap and let the pressure out.

The cap has a one-way vent and I guess I wouldn't want to change that since it would leak in a roll or off camber situation. I'm thinking I need to just plug the return line on the tank and let the line vent. Am I on the right track?

[ June 12, 2005, 10:19 AM: Message edited by: robselina ]

[Frank in Norway]

You need a better vent line. Sounds like the one-way in your cap isn't working correctly.
The fuel and return lines from the carb shoudn't have anything to do with this.

[blt2krl]

Rob, I agree with Frank. I have the same Cell and have never had your problem mentiond. I fact I bought a roll over vent fitting from Summit cause I feared what your talking about. I have never had to use it, so it sits on my self in the shed. Call Summit and see if you can't get a new cap.

[Berrett]

i run the same cell only smaller (12 or 16 gallons). my jeep didn't have a return line so i just run the pickup line and vent the other to the outside and have had no problems.

[ June 12, 2005, 10:58 AM: Message edited by: Berrett ]

[robselina]

Originally posted by blt2krl:
Rob, I agree with Frank. I have the same Cell and have never had your problem mentiond. I fact I bought a roll over vent fitting from Summit cause I feared what your talking about. I have never had to use it, so it sits on my self in the shed. Call Summit and see if you can't get a new cap.How's yours plumbed in Paul? I took the cap appart and it seems to work properly. It allows air to flow INTO the tank but not OUT of the tank. Basically, it's setup to allow air to replace spent fuel in the tank but not to relieve positive pressure inside the tank. Know what I mean?

I think it's something to do with the emissions junk I partially have on the rig still (mostly gone) cause the tank clearly can't vent through the lines right now....

[robselina]

Originally posted by Berrett:
i run the same cell only smaller (12 or 16 gallons). my jeep didn't have a return line so i just run the pickup line and vent the other to the outside and have had no problems.Yea, that's how I'm thinking I need to plumb it up. I used one of the smaller ones on the Scout I'm building and it didn't have a return line so I vented the return and it seems to work hunky dory.

...

I'm getting rather eager to shed some pounds up front (heater, AC compressor, etc) and simplify my vaccum and electric systems to the point I understand them (right now they're both a mess). I might have to bump that project up on the list since it'll make understanding what's going on under the hood and dash a lot easier...

[Frank in Norway]

I don't think you're tank is beeing pressurized. I think it's vacuum that happends.
If it's building pressure, your engine will stall from beeing run way to rich. That is if it will stall at all.
If there's enough pressure on the tank the fuel pressure will overcome the float needle and the engine will run rich.

But if the tank can't vent enough it will be vacuum on the tank and the engine will not get enough fuel. So when you unscrew you cap you let pressure nto the tank rather than letting it out.

Isn't there a outlet so you can install a seperate vent line on the tank?

[blt2krl]

Originally posted by robselina:
</font><blockquote>quote:</font><hr />Originally posted by blt2krl:
Rob, I agree with Frank. I have the same Cell and have never had your problem mentiond. I fact I bought a roll over vent fitting from Summit cause I feared what your talking about. I have never had to use it, so it sits on my self in the shed. Call Summit and see if you can't get a new cap.How's yours plumbed in Paul? I took the cap appart and it seems to work properly. It allows air to flow INTO the tank but not OUT of the tank. Basically, it's setup to allow air to replace spent fuel in the tank but not to relieve positive pressure inside the tank. Know what I mean?

I think it's something to do with the emissions junk I partially have on the rig still (mostly gone) cause the tank clearly can't vent through the lines right now....</font>[/QUOTE]I have mine setup like yours. Pickup line and Return line. I have zero emmision equipment on my rig. How would that allow your tank to pressurize? Your saying that your tank is swelling or sinking?

[jeepzilla47]

just like when you have a 5 gallon gas can....close it up and shake it, when you shake it, it will swell up...i just started my truck this weekend with the fuel injection and the fuel cell, and my tank started swelling..i am also looking at putting in a vent/rollover valve in the top on mine...

[robselina]

it's swelling. It fills up like a ballon. Just like Frank says above, it stalls the engine out 'cause it runs too rich. It can also make it hard to start 'cause it floods the engine...

Originally posted by Frank in Norway:

Isn't there a outlet so you can install a seperate vent line on the tank?THere's the pickup line and then a second fitting which I'm presently using as a return. I'm thinking ditch the return since that's a remnant of the old emissions system and run it through a roll-over valve and vent it....

[ June 12, 2005, 03:52 PM: Message edited by: robselina ]

[robselina]

Originally posted by blt2krl:
[QUOTE]I have mine setup like yours. Pickup line and Return line. I have zero emmision equipment on my rig. How would that allow your tank to pressurize? Your saying that your tank is swelling or sinking?Swelling like a ballon. When it was flooding out yesterday when I pulled the filler cap it actually popped off, not just a bunch of gas escaping but it litterally jumped up 6". :S Not sure exactly what's happening but that return line has to be part of the problem, no? It's presently hooked up to a second fitting on what I assume is a carbon fuel filter. I'd imagine it's for drainback this way but it was probably initially hooked up to a carbon canister that isn't there anymore. Dunno, my engine bay is a bit of a mess, that's why I'm thinking I need to clean it up a little so I can understand what's going on....

[Frank in Norway]

OK, here is the plumbing I have on my fuel tank.
One pickup line that goes from the tank to the mechanical fuel pump. Then a line from the pump to the stock filter. on top off the filter there's a outlet to the return line and a on the center off the filter there's the line that goes into the carb.
I also have a vent line on the tank that has no check valve, but the tubing is very long and coiled so that it's no way the fuel can escape from the tank this way (rollover tested).

Except for the vent line, this is the stock setup.

The fuel stock filter is design so when it fills up, the excess fuel can drain back to the tank. However, most trucks with carbs don't have a return line.

If you remove the return line, you could come into problems with the fuel pressure beeing too much for the float needle spring to overcome, but I doubt it. Remove the return and use this as a vent line. If this turns out OK, use it this way.

[robselina]

hum, the way you have it routed Frank is exactly how I have it now....weird.

If I remove the return line I assume I should plug that line that second line that comes out of the fuel filter right?

[Frank in Norway]

Yeah you should plug the return on the filter.
There's one difference in the plumbing. I don't have a check valve on the vent line.

[Max Power]

I'd keep that return line and run it into a 'T' @ the tank w/ your check valve and vent the other side.

I appreciate franks skills, but I'll bet it gets a little hotter in new mexico than in Norway. If you don't vaporlock, the return line is part the reason.

Altho I removed my emissions junk too, I kept the carbon canister... if you've still got it, that where you should vent the tank to. It does not adversely effect performance and is very beneficial environmentally.

cheers,
RObert

[robselina]

canister was gone before I bought it....

Was working on a friend's ZJ last night but we'll get back to the waggy today. We'll see how it goes....

[pb]

Seems to me, that a different gas cap would be the easiest solution. I'm not sure what is availble, but I would think that there would be some that release pressure at a certain psi. Or a pin hole or two in the cap to let the pressure out, but hardly any fuel in a rollover.

[Frank in Norway]

Originally posted by Max Power:


I appreciate franks skills, but I'll bet it gets a little hotter in new mexico than in Norway. LOL, I guess it does. But I'll trade it for our winter anytime :)

[robselina]

Originally posted by Frank in Norway:
</font><blockquote>quote:</font><hr />Originally posted by Max Power:


I appreciate franks skills, but I'll bet it gets a little hotter in new mexico than in Norway. LOL, I guess it does. But I'll trade it for our winter anytime :)</font>[/QUOTE]I'll take that deal smile.gif I moved to the wrong state, I love it cold and hate it hot...

As for the little problem, It's 90% resolved, I'm just waiting on my rollover valve to show up. Last night we disconnected the return line and replaced the fuel filter with a standard two plug canister type. Engine runs great, no idle issues or stalling. Hopefully when I get it out in the heat we won't see any vapor lock issues!

[ June 15, 2005, 01:38 PM: Message edited by: robselina ]