Fuel Tank Swap Question... '91 FWD to '94 AWD

[Crashsector]

Hey everyone -

This is the latest bug to creep up with my swap. Since my body donor is 2WD (and a 1991), I have to swap the 1994 AWD fuel tank in to have clearance for the drive shaft.

My problem is this. Most of the lines match up. There are three lines that end up on the driver's side of the tank which go to the car body. That's good. And the filler and the filler vent seem to match up just fine.

However there are 3 what look like vent lines on the '94 AWD tank that have nowhere to go on the '91 body. They are right next to the filler. Does anyone know what's up?

My feelings are that they are a part of a more comprehensive evap system that was on the 94 but not on the 91. If this is the case can I just seal them off?

Also, there seems to be an extra wiring harness on the drivers side of the '94 AWD tank that doesn't have anywhere to go on the '91 body. The 6 pin connector to the fuel tank matches up just fine. Is this extra 2 pin connector part of that evap system? I hope its not a sender for the fuel level. I thought that was part of the assembly with the fuel pump on the passengers side of the tank.

Thanks for any help.

--Andy

[vrg3]

Have you read all about Josh's writeup? It sounds like you're talking about the vapor separator and the second level sender.

[Crashsector]

Have you read all about Josh's writeup? It sounds like you're talking about the vapor separator and the second level sender.

I have, but I didn't quite pick up on what it was saying. I thought he was talking about a sedan vs. wagon difference, not an AWD vs. FWD difference. I'll re-read it tonight at work and see what I can come up with.

Any help in the mean time? I'd love to get this back up into the car tomorrow if possible.

Thanks guys!

--Andy

[vrg3]

I don't know about the vapor separator off the top of my head; that's why we have the BBS with the searching feature and that's why Josh wrote his writeup. Try searching specifically for "separat*" with "Legacy777" as the author.

As for the harness, I do believe it's for the level sender because AWD tanks have that split. You need to connect both level senders in series -- assuming you have an AWD sender mounted with the fuel pump. If you kept your FWD sender, then you can just leave the new sender disconnected and you'll just have to deal with the gauge moving up and down as fuel sloshes side to side.

[Crashsector]

OK, re-reading Josh's writeup helped. I've read that thing at least 3 times but before dropping the tank. It all makes sense now.

So I think I'm just going to route the two separator lines into the charcoal canister and see how it does. I will probably end up just leaving the second fuel sender unplugged for now too. If it gets to be too much of a problem I'll deal with it down the road.

Thanks for all the images and writeups on your site too vrg3. They will no doubt be invaluable this week!

Thanks!

--Andy

[vrg3]

No problem, good luck!

[Crashsector]

So I wonder if there would be any problem just capping off those three extra vent lines. There is already a vent line that runs up to the charcoal canister from the fuel pump area. I can't find brass T's that are the right size and I'm hesitant to use plastic that isn't fuel rated.

Is this a dumb idea?

--Andy

[Legacy777]

There should be two vacuum/vent lines coming off the AWD tank. These should go to the fuel separator. There is a line off the separator, that then connects to the charcoal canister.

If you don't want to put the fuel separator in, you could tee the two vent lines and the line going to the charcoal canister together. If you do this, try and mount the tee or keep it in a high position to help keep liquid fuel from entering the evaporative fuel system.

Regarding the fuel senders, everything should be fine with the wiring, unless the tank wiring was cut. The wiring for the senders are in series, so everything connects through the main fuel tank harness.

You can NOT use the FWD fuel pump assembly, or sender, since it's different for the AWD tank.

Look at this picture, and you can see the wiring and how the vacuum lines go for the AWD tank
http://www.surrealmirage.com/subaru/ima ... P_3120.JPG

[Crashsector]

Josh -

Your garage looks a lot like mine I wanted to save some time since I thought I would be able to work on the car this week and just cap the lines off since I couldn't find the appropriate T's. It turns out I'm moving this week so I'll just order them online and work on it next week.

Thanks to both of you for your help. Your writeups have been invaluable and I can't wait to get this beast running. Next step... figuring out if it will run (well) with 680cc injectors and a JECS MAF with no EM. Not looking forward to that.

--Andy

[Crashsector]

OK, so this is the situation. Here is a drawing of the AWD fuel tank:



The three lines in blue are my problem. The two on the left just come straight out of the tank and the one on the right goes over the tank and over to the area where the lines go up into the body.

I'm assuming, judging from what I've read from Josh's writeup, that the two lines on the left go to the separator and then the fumes go into the line on the right and up to the engine compartment.

That being said, this is how I'm planning on tee'ing it.



The tee would be mounted up high so as to prevent fuel getting into the charcoal canister. Anyone see any huge problems with this? Am I completely off base?

Thanks!

--Andy

[Legacy777]

Like I said in the email, the second drawing looks good.

[speedoboy31]

i just got done with stealing 4wd from a 93 wagon to make my 92 sedan into 4wd. all i did was capped the right5 side vent and connected the one closest to the center of the tank to the one running across the tank and all has been well for a couple hundred miles so far. i am getting a lot of guage fluctuation. don't know the fuel level situation of the wagon prior to this. i almost suspect that i may need the cluster from the wagon(matching?) i ran into this with a ford taurus----anti slosh module was part of the fuel guage in dash and that needed to be matched with the sending unit in tank. anyone already deal with this? solution?

[Legacy777]

If the senders are functioning correctly, you shouldn't really get any fluctuation. I ran into issues with mine after a year or so, and ended up replacing both fuel level senders.

There's a delay circuit that is there on the AWD vehicles.....at least for the 92-94 MY's according to the FSM. I don't remember if the 90-91's have it, however like I said, if the senders are working correctly, you shouldn't have any problems.

[speedoboy31]

legacy777, if you have the fsm,could you check a location for the delay module? alldata doesn't show a location.only shown in a circuit diagram. btw, my gauge seems to be working better and better. gotta wonder if the level resistor corroded a little during the 1.5 years the parts car sat and is now wearing in?????

p.s. still doing well with1 vent---no odors or evap codes----8--900 miles so far.

[Legacy777]

The fsm doesn't show a location of the delay module, just that it's in the circuit. Sorry.

I'm sure they were a little corroded, so yeah they may be getting better. Plus during the winter, ethanol gas is more typically used which can help eat some of the corrosion off.

[speedoboy31]

thanks for checking leg777. oh,well

[nottofast]

Got exactly the same situation swapping a 93 SS Wagon into a 92 Fwd Sedan currently. I am just going to swap everything over. The coating on the tank is flaking off is there a spray can alternative?

[Legacy777]

Yeah, you can get spray can undercoating. It's flaking off my tank too, but depending on where you live, I wouldn't worry about it too much.

[thenicky0]

OK, so this is the situation. Here is a drawing of the AWD fuel tank:



The three lines in blue are my problem. The two on the left just come straight out of the tank and the one on the right goes over the tank and over to the area where the lines go up into the body.

I'm assuming, judging from what I've read from Josh's writeup, that the two lines on the left go to the separator and then the fumes go into the line on the right and up to the engine compartment.

That being said, this is how I'm planning on tee'ing it.



The tee would be mounted up high so as to prevent fuel getting into the charcoal canister. Anyone see any huge problems with this? Am I completely off base?

Thanks!

--Andy

Anyway of getting these images rehosted?

[Legacy777]

You can try PM/emaling the original poster. If that doesn't work, you can d/l the parts book from me which has those diagrams (without the markings).

http://bbs.legacycentral.org/viewtopic.php?t=30531