How does the gas tank on a 55 work?

3jvj · 09-16-09, 09:48 PM

I'm trying to track down a starving fuel issue (posted in 40-55 section) and I'm thinking it's tank related. Are the four hoses on the top capable of causing a vaccuum condition that will stop flow? Is there a service panel on the top of the tank? Anything I should know prior to dropping the tank?
I didn't see much point in asking in the 40/55 sections as the systems are different.
Thanks.-JJ

thread in 40 section

3jvj · 09-16-09, 09:59 PM

Could somebody post a pic of a factory tank?

I just dumped 30 something out and another gallon or so on my floor (plus the couple I burned driving today). My search for clues indicate a sub thirty tank was stock.

cruiserbrett · 09-16-09, 10:29 PM

check the last page of eventhough's "resurrection of the beast" thread

3jvj · 09-16-09, 10:38 PM

Will do. Thanks Brett.

3jvj · 09-16-09, 10:47 PM

my buddy's "w.t.f. is that? Is that a gas tank or a skid plate for boulders?" comment is coming clear now. I'll snap a pic for id purposes. Doesn't look like that but still has the four lines on it.

PabloCruise · 09-17-09, 09:04 AM

I have some pics here:

http://forum.ih8mud.com/fj55-iron-pi...gassy-pig.html

cruiser_guy · 09-17-09, 09:24 AM

There are 7 or 8 connections on the tank. Four small lines are vent lines going to each corner, there is a slightly larger one that goes up to the filler, there is of course the large filler line and then the pickup and return lines.

Ming89FJ62 · 09-17-09, 09:41 AM

The gas tank is vented by the valve on the carcoal canister (Outer Vent Control Valve) and the vacuum control valve (VCV) depending on the ignition switch (outer vent control valve) or engine temp for the VCV.

PabloCruise · 09-17-09, 09:44 AM

And the check valve located in the rear quarter on the vapor separator

3jvj · 09-17-09, 04:45 PM

Lotsa check valves.....

yay.

Thanks. Dropping tank tonight.

Any guesses where my problem lies?

Six pack for the winner.

3jvj · 09-17-09, 06:26 PM

Wife has first aid/cpr class; no piggie time for daddy. :(

Just out of curiosity, would a vented gas cap solve the vac issue?

PabloCruise · 09-17-09, 07:38 PM

Help us understand - is this a stock tank?

Can you easily pass air through the fuel and return lines?

If yes, can you easily pass air (low pressure, 10 psi) into the tank from the main fuel supply line (line from tank to engine)?

3jvj · 09-17-09, 08:30 PM

Not sure if it's stock but it holds 30ish gallons, has a drain plug, and no return line. It has the 4 lines next to the filler, and a breather to the filler. Seems like it would be silly to have that on an aftermarket tank but everything I read lists a 23-25 gallon as stock.

I've got a baby sleeping on me. I'll post a pic when I unload.

3jvj · 09-17-09, 08:32 PM

and yes; I can back blow the tank pretty easily (with the cap off).

cruiser_guy · 09-17-09, 09:12 PM

Quote:

Originally Posted by 3jvj

Not sure if it's stock but it holds 30ish gallons, has a drain plug, and no return line. It has the 4 lines next to the filler, and a breather to the filler. Seems like it would be silly to have that on an aftermarket tank but everything I read lists a 23-25 gallon as stock.

I've got a baby sleeping on me. I'll post a pic when I unload.

Usually the long range tanks are boxy shaped with no pressed metal parts. The factory tank is two pressed metal halves brazed or welded together. The long range tank in my '55 had no drain plug when I bought it (I put one in 'cause I was having leakage issues and had to drain it) and nor does the one in my BJ60

PabloCruise · 09-17-09, 10:17 PM

The lack of return line may be causing you trouble, but I am not sure what powerplant you are running. Can you provide us with more details about your Pig?

Engine?
Fuel system?
Other important mods?

Can you elaborate what you mean by "starving fuel issue"?

3jvj · 09-19-09, 11:44 AM

Just one of those things.....

If your buddy busts some wires on your sensors:

Two days later you get to fix this:

Before you can get to this:

Not sure of make. Not sure of purpose. So I should be able to blow air freely through all yes? That's my theory anyways. I'll post up results after I fix my other stuff. I've been thinking of converting an old scissor lift into a bike lift; may do that before I get into dropping it. Save my herculean biceps from tearing apart (or rather my ignorant arse from ripping of a hose/wire I didn't know about that is made out of some rubberized fj55 unobtainium material

).

3jvj · 09-19-09, 08:55 PM

Welp. It's got some rust but no where near the amount I would need to cause the issues I'm having (imo). When I diconnected the hoses off the side of the tank the filler vent (I assume) was full of fuel. It was the fifth hose and closest to the filler neck.

Should it have been full of fuel? Is this my probleM?

Is this a factory long range tank?

I'm thinking not as there was no line for a return to tank. I also have one extra hose that didn't go into the tank that is zip tied up with the others.. (canister maybe???).

All in all it went pretty clean. Had to man handle it to get it past the springs but the one bolt that gave me issues came out without snapping (easily cleaned with a tap). The sender was pretty junked, and the rod was way too long; hence the no "full" on my gauge. There was also a spliced wire to the sender. I think I'll run a fresh wire to the guage to eleviate any ohm drop that might be screwing with me as well. There are no baffles in the tank either. Seems like an oversight for such a large tank. The pickup was right under the sender; crummy for uphill as it's right up front.

Hope this helps someone out in internet land as I'm still scratching my head on what my real issue is. I'm giving thought to canning the entire vapor recovery system out of the mix to close it as a possible problem area.

PabloCruise · 09-20-09, 12:42 AM

Quote:

Originally Posted by 3jvj

I'm giving thought to canning the entire vapor recovery system out of the mix to close it as a possible problem area.

I don't think you want to do that...

PabloCruise · 09-21-09, 12:32 PM

Quote:

Originally Posted by Ming89FJ62

The gas tank is vented by the valve on the carcoal canister (Outer Vent Control Valve) and the vacuum control valve (VCV) depending on the ignition switch (outer vent control valve) or engine temp for the VCV.

My '74 does not have this Outer Vent Control Valve on the charcoal cannister that you speak of - looks to be a '75-'79 item...

cruiser_guy · 09-21-09, 04:20 PM

That's an aftermarket long-range tank, NOT factory. There should be the pickup and return line in the corner where your light is.

No, the fill vent should NOT be full of fuel unless the tank is too. It simply vents air past the fuel when you're filling up.

3jvj · 10-25-09, 08:07 PM

Yeah.......

This was the first rinse.

Good to go now.