Centennial!

Okay, i have searched and searched and there are a lot of conflicting answers ("mine has this") and I cant tell what is true or what is SWAG.

Does anyone know for certain what size gas tanks were offered on a 1988 regular cab, SWB, 4X4, manual, F150 with a single rear tank mounted above the spare tire? Im asking because i would like to put in the largest tank that will fit without any modifications.

I sure appreciate anyones help.

Chip

Steve83

You're asking 2 different things...

The only rear tank in an F150 ('80-96) is 18.2gal.


(phone app link)

The largest you can fit without cutting or drilling would be the 32gal Bronco gas tank. But you'd have to relocate the spare tire.

In any case: you need a tank with the same size pump-mounting hole as what you have now (the '87-96 large hole); and a pump mounting plate that matches the tank depth, and your wiring, and your fuel lines.

What's wrong with the current tank? Does the truck have 2 tanks? What exactly are you trying to accomplish?

sdmartin65

That answer is only partially correct let me clarify. Your configuration of truck was only ever offered with the rear tank. Being 4x4 the front tank wouldn't fit. F series were offered for a few years, I believe 87 to 91, with a 36 or 38 gallon rear tank. I've seen a write up in the past from a obs diesel owner installing this fuel tank. It is not a Bronco tank as it is narrower and would require modification to install. Best place to look for this tank is LMC truck, the other hardware needed for this modification are also sold there. I'm sure other suppliers sell this tank but LMC is a good place to help visualize the complete parts needed because of how the catalogue is set up.

Centennial!

Thanks guys. Nothing is wrong with my tank but if it's 18.2 gal, then i have a problem with the accuracy of my gauge, float etc. Ideas there?

When my gas gauge reads completely empty and i fill it up, it takes about 12 gallons and has been consistent hence my assumption that i have a small tank. Gauge doesn't move until i have consumed 2 gal or about 30 hwy mi. Obviously, who cares if a fuel gauge isnt accurate when full, but inaccurate when empty is a guessing game. I track my mileage very closely so i can make it work but would rather have plenty of fuel so i dont have to worry/calculate etc. Not a problem in town or on the highway but in remote areas of CO in 4WD, i would like more margin.

Thanks again and i really appreciate your help,
Chip

sdmartin65

Bring a couple gallons in a can and track a full tank to when it runs out. I'd bet you'll hit close to 250 miles. Without taking the pump out and fixing you'll know how far a tank can go this way.

Centennial!

Okay, I ran the tank dry at 233 miles. Added a gallon of gas, drove 6 miles to the gas station and put/ "squeezed" exactly 13 gallons into the tank. So, i drove 239 miles and filled up with basically 14 gallons (minus the gas to go the 6 miles) That puts me in the high 16 mpg range which is normal for this truck on the highway. So, this truck must have a special order small tank in the 14 gal range.

Now, does the cost and effort to put in a 18.5 gal tank justify the added 40 to 60 miles i can get out of a tank of gas? Decisions, decisions...

Thanks for the help Steve & Martin.

BLDTruth

It's an 18.2 gallon tank. It just doesnt like to fill up all the way unless you pop the drivers side rear tire up off the ground about 6 inches with a ramp or jack. Ask me how I know lol. Mine does the same thing only fills up about 14 gallons tops on flat ground. It's stupid.

Centennial!

Thanks for the tip BLD, ill give that a try just as a last data point before i start gathering the parts/knowledge for a new tank. Would hate to put the expense for a new one and the work to get mine out only to find its actually an 18.2 and would function the same the new one i just bought. Oh yeah, that would send me into orbit!