Gas tank

[72cut]

88 comanche 4.0 long bed. 18 gallon gas tan?

[eaglescout526]

Long beds only came with either a 16 or 23 gallon tank. 18 is for the short bed. 

[72cut]

Ok so it's just my preference? No idea what is in it now, either will fit right in?

[eaglescout526]

Yeah it’s how ever much money you want to put into the tank haha. Chances are you have a 16. If it’s original it should have the info tag on it either under or by the sending unit hole

[72cut]

Thanks buddy yes price is issue, thanks

[72cut]

While I have you, trying to cipher out gas having hell of a time getting tube down in there. The tube I bought has 3/8 inside diameter and 1/2  outside diameter. Too thick or is there a trick to this, seems pretty damn straight forward

[fiatslug87]

Have you added the VIN to the registry? Many build sheets have the tank size listed. I would go with the larger tank, I’m sure price isn’t that much higher.

[Pete M]

26 minutes ago, fiatslug87 said:

Have you added the VIN to the registry? Many build sheets have the tank size listed. I would go with the larger tank, I’m sure price isn’t that much higher.

 

unfortunately the longbeds printouts usually say 20gal (which is the XJ tank) and I change them all to 23.   I figure if someone is replacing it, they should hunt down the 23.  plus if I remember right, the 16 and 23 are the exact same tank, just the 16 has a longer tube which prematurely cuts off the fuel input. 

[eaglescout526]

1 hour ago, fiatslug87 said:

I’m sure price isn’t that much higher

I’m talking to fill the tank with gas haha

 

37 minutes ago, Pete M said:

just the 16 has a longer tube which prematurely cuts off the fuel input. 

Correct. And I think that’s where the OP is hitting his snag on getting the hose in there. He is probably better off removing the sending unit or putting power to the pump to get the gas out. 

[fiatslug87]

JMO413 got the build sheets for my 89 LWB and 90 SWB and they say this, I don’t think he edited them:

NF2 18.5 g fuel tank on the 90 SWB

NF5 23 g fuel tank on the 89 LWB

both correct

 

These were gas tank codes (not all MJ) from the 1989 (I think) code list Pete had found and posted, I put it all into an Excel sheet:

NFA	20 GAL TANK FUEL
NFB	22 GAL TANK FUEL
NFE	30 GAL TANK FUEL
NFF	35 GAL TANK FUEL
NFS	15 GAL TANK FUEL
NFU	34 GAL TANK FUEL
NF2	18.5 GAL TANK FUEL
NF5	23 GAL TANK FUEL

 

The 16 gallon tank was one offered in 89, from the 89 sales book:

[72cut]

So, remove the pump from the tank with the tank still installed to siphon out the gas?

[Pete M]

35 minutes ago, 72cut said:

So, remove the pump from the tank with the tank still installed to siphon out the gas?

 

last time I had to do it, I brought 12v to the pump and used it to pump out the gas.  but inspecting the pump is never a bad thing.

 

don't forget that if the gas level is above the pump, it'll make a giant mess in your face if you pull the pump out.  

 

how old is the gas in the tank?  how much gas is in the tank?

[JZLAJeep]

Brings back memories of when Jared (J in JZLA) got a mouthful of stinky bright orange gasoline when siphoning 5+ year old fuel out when we brought the MJ home. Never seen someone wash their own mouth out with soap before that. 

[gogmorgo]

If it’s below 1/2 tank it won’t spill gas on you pulling the sending unit if that’s what you’re doing. 
 

Don’t put your mouth on the hose when you’re siphoning. 
If you’ve got access to compressed air and a blow nozzle, blow it across the end of the hose. For a larger hose, cut a hole near the end, stick the blower in the hole and blow towards the end of the hose. Or just put the blower into the same hole you’ve got the hose in and seal it off with a rag to pressurize and blow the hole out. 
Alternatively if you’re having trouble coming through the filler neck and replacing the tank anyway because there’s a hole in it, just make the hole bigger and either put the hose in there or stick a drain pan underneath and catch it coming out. 
 

My preference is to pull a fuel line, pop out the fuel pump relay, and jump across pins 30 and 87. Pump it dry, put the relay back. Of course that only works if the fuel pump does. But it keeps any potential sparking well away from where you’re working with the fuel. 

[72cut]

It has about a quarter tank, most of which is about month old, enough old gas in there to have the varnish smell. I don't hear the pump come on when octuem key. My thinking is the pump needs replaced. The tank does not seem to leak, was thinking to just replace it anyways. Now I'm thinking just remove the protective plate and try to just replace the pump assembly. How difficult is this with tank in truck? Should I use something plastic to try to disengage the ring to prevent spark? I have no idea how difficult this is or isn't 

[fiatslug87]

Use a brass punch (piece of brass rod works well) to remove the lock ring. There is plenty of room to remove the sender with the tank in place.

[eaglescout526]

Why not put 12v to the pump to see if it works and have it dump the fuel into a bucket? I mean yes check the condition of the pump and sending unit but I feel like it would be alot less work if the pump works and you can get the old fuel out that way.

[Pete M]

month old fuel is practically brand new fuel.    unless it's been open to the air it should be fine. 

[72cut]

Thanks to all