fuel tank question

[jeepboy45]

Hey jeepers...

Currently I have a 20 factory poly tank from a 1985 "ish" CJ in my 1979 CJ7 . But I was wondering if anyone here has put a factory 15 gal poly tank from a 1991 Wrangler in a CJ?

I know that the 1990 is shaped more like the older CJ's rectangular tank. All that is required is to turn the tank 180 degrees to get the fill lines on the correct side to fit a CJ...

But the 1991 is oddly shaped and I dont know how it will fit...

 

[harleydragon]

the 91 was fuel injected so the fuel pump will be way too much pressure for a carb ( fuel pump is in the tank )..also,the fuel gauge sending unit is not compatible with your gauge..I don't know if it will fit when you flip it around but you will need much longer fill hoses because that will place the tanks filler tube at the front of the tank rather than at the rear..In a yj the tank is a really tight fit so no doubt would be the same in a cj..you might have to reroute your exhaust also..no doubt it will be a lot of work adapting everything..the one good point is that all the 91-95 yj tanks were actually 20 gallon tanks..if it was bought as a 15 gallon then the filler vent tube sticks into the tank several inches,making the tank think it is full with only 15 gallons in it..you can cut this vent tube off so that it only sticks into the tank 2 or 3 inches and you then have a 20 gallon tank.I currently have a 91 that I did this to so I know it is a fact..Chrysler just got over on people,charging them extra for a 20 gallon tank when it fact it was the same tank,with just a different length vent tube

 

[Jimbos76cj]

turn it around and see is about the only way you will know. Like Harley said the fill lines will need to be modified since the inlets will be further back. For the fuel gauge they reading is backwards so you can pull the gauge, use a sharpy to change the F to a E and a white marker or white out to make the F to a E.

 

[jeepboy45]

At Harley... I remember you told me about chrysler doing that to 20 gal tanks... freakin crazy!! I am going fuel injection which I would like to have 45 gpm at 15 psi... In 1990 the in-tank pump put out the same gpm at about 30 psi.. Not too far off... In 1991 the pressure is nearly 75 psi if I recall correctly. More than I want.. I am having an issue with a particular local junk yard, and getting this 1991 might be the only resolution, or I lose $$

At Jimbo.. LOLOLOL, thanks for the sharpie idea! But I currently have auto meter gauges and am not sure yet what to do about that issue. Auto meter has a lifetime guarantee, maybe they can help me out switching out a gauge? Not sure yet.

I currently have a rectangular 20 gallon tank with the exhaust running out the drivers side back corner....around the tank...

 

[harleydragon]

I'm thinking that those fuel pumps are putting out 30 something pounds.the fuel pressure regulator is mounted in the top of the fuel pump.you can ohm the sending unit,at empty and full positions to see what gauge you need..

 

[jeepboy45]

@harleydragon..

I picked up a poly tank with a manufacture date of 11-1987..

The owner didnt know if it was from a fuel injected Jeep or carbureted... Apparently it was not injected as there was no pump in the tank... Since you know a good deal about these tanks, do you know if I got a sending unit for a Jeep that was injected, (with the fuel pump attached to it) will it fit in this tank?

 

[jeepboy45]

I am honestly getting a bit frustrated...

The tank is NOT perfectly rectangular. It has two 45 degree corners.

The sending unit is NOT held in with a round locking ring.

The pump is NOT in the tank.

I've been searching on Rock Auto from 1987 to 1995 and cannot find what the heck this is. The owner was fairly sure it was a 1987 because of the stamping on it. But theoretically it could have been put in any year after 1986... So I dont know what the heck I have here.

trying to attach a pic or two, but my damn phone camera is acting up as well. Now I'm just trying to remain calm and not break it....

AARG

 

[jeepboy45]

I used orange spray paint to get the information to appear better on a picture.

 

[jeepboy45]

I am honestly getting a bit frustrated...

The tank is NOT perfectly rectangular. It has two 45 degree corners.

The sending unit is NOT held in with a round locking ring.

The pump is NOT in the tank.

I've been searching on Rock Auto from 1987 to 1995 and cannot find what the heck this is. The owner was fairly sure it was a 1987 because of the stamping on it. But theoretically it could have been put in any year after 1986... So I dont know what the heck I have here.

trying to attach a pic or two, but my damn phone camera is acting up as well. Now I'm just trying to remain calm and not break it....

AARG

I am assuming that the pictures of parts on the rock auto site are a bit generic. So trying to identify based on pics of parts is NOT the way to go.

Morris 4x4 seems to have good pics to go with their parts. So, based on those it would appear that I have a 20 gallon (just test-filled it) tank from a 1987 "ish" Jeep with a 4.0 carbureted engine.

However, there is the shape of the tank which I dont know goes with what year Jeep...

 

[harleydragon]

all the 4.0's in the wrangler were fuel injected and had the pump in the tank..91-up was 4.0..90 and earlier 6 cylinders were the AMC 258 i6 / 4.2l (AMC 258 i6 / 4.2l ) ,had a carb and mechanical fuel pump

 

[jeepboy45]

all the 4.0's in the wrangler were fuel injected and had the pump in the tank..91-up was 4.0..90 and earlier 6 cylinders were the AMC 258 i6 / 4.2l (AMC 258 i6 / 4.2l ) ,had a carb and mechanical fuel pump

Based on the shape, and sending unit, and stamping on tank, I'm still trying to figure out what sending unit to BUY for this tank to utilize an in-tank pump

 

[harleydragon]

it has been a long time since I had the tank out of my 91 so I don't remember if the cover that holds the sending unit,fuel pump on mine is the same or not..I am thinking that it is different..you might could build an adapter plate and use a 91 up pump..only other options I can think of would be to use an inline pump

 

[jeepboy45]

this thread has taken a different direction than I had first hoped...

This is a part from Morris 4 x 4...:

Sending Unit, 15 Gallon, with Fuel Injection and Pump - 83502955K

It is an in-tank mounted pump for a wrangler... Notice the round mounting flange...

My Q is this: Is this the same round flange that is found on a CJ tank? Specifically a 1985 poly 20 gallon tank...

I just picked up a 1988 20 gallon poly tank that I can get a pump/sending unit for, but I like the way the 1985 tank fits in my 1979 CJ7 . If the part above is a factory replacement part, then my thought is I can surely find one of these used somewhere, and install it in my 1985 tank...

 

[harleydragon]

http://www.summitracing.com/int/parts/omx-1772409/applications/make/jeep/model/cj7

the one you pictured looks to mount exactly as this one to me

 

[jeepboy45]

Yes, it looks like the same locking ring...


That is exactly what I am focusing on...If it is the same diameter locking ring, what is stopping me from mounting the pump mounted sending unit in an older tank??????

And why havent more people done this already???

 

[harleydragon]

sounds like a great idea to me..I never knew that they made a pump setup like the one you found..Personally,I like carbs and I prefer the bigger inline fuel pumps that mount outside the tank..I like being able to get to it without dropping the tank and,even though it might be my imagination,I still think of bigger as being more durable

 

[jeepboy45]

sounds like a great idea to me..I never knew that they made a pump setup like the one you found..Personally,I like carbs and I prefer the bigger inline fuel pumps that mount outside the tank..I like being able to get to it without dropping the tank and,even though it might be my imagination,I still think of bigger as being more durable

It all comes down to the diameter of that round locking ring, whether it is the same as the old-school CJ tanks...

AND if the overall length of the sending unit will even be correct.

Wait a sec... women have been telling me for years that bigger isnt always better....were they lying to me!!?? DAMN!!!

 

[harleydragon]

no guarantees but I would bet that it would be a perfect fit...you know that many times they just tell you what you want to hear

 

[ThisGuyUKnow]

Well you have two problems with that fuel pump. Even if it fits, you still have to solve the issue of the Yj sending units incompatibility with your CJ fuel gauge. Also you are talking about a using the pump in a 20 gallon tank when it is a 15 gallon sending unit that you linked. If the depth of the tank is different then you will not be able to get all the way to the bottom of the tank.

 

[jeepboy45]

Well you have two problems with that fuel pump. Even if it fits, you still have to solve the issue of the Yj sending units incompatibility with your CJ fuel gauge. Also you are talking about a using the pump in a 20 gallon tank when it is a 15 gallon sending unit that you linked. If the depth of the tank is different then you will not be able to get all the way to the bottom of the tank.

supposedly the only difference between the 15 and 20 gallon poly tanks isnt the actual tank, it is is the fill hose that has been altered to only "allow" 15 gallons to be put in... The dimensions are supposedly the same... I'm just going by what I've been told..

Yes, the gauge is an issue, but I've had auto meter gauges for 10 years. I am contacting them Monday to get one (or figure out a fix) for the ohm differences. But I'm sure that can be overcome.

Fuel pressure/gph was a concern but after looking at the specs of stock fuel pumps for 1988 Wranglers, they are very close to the Holley pump that feeds the Holley EFI kit I have. So that is resolved as well.

I hate NOT having one of those sending units in my hands to actually see one in person... the guys at 4wd .com or Morris couldnt tell me anything about the specs. I seem to know more than they do..and thats kinda scary.

Its a sad world when people go strictly by application and dont open their minds to the possibilities of making things "work"...

I really need to find a used sending unit and check if it is going to fit properly. Then I can safely move ahead.

If anyone out there has a tank laying around with a round-flanged sender and pump attached, I'd be indebted if you could take measurements of it... The diameter of the locking ring, length from top to bottom, any anything else that might be pertinent.