gas tank swap

[88marmon]

My 86 GMC longbox has the stock 16 gallon dual gas tanks. The truck was converted to TBI, and the drivers side tank had the fuel pump installed. The auxiliary tank was not converted. I assume the 86 tank has no baffles, as it will begin to run out of gas when braking with 5 gallons left in the tank. I would like to upgrade both tanks to the FI style and would also like to increase to 20 gallon tanks.

Do the larger tanks bolt right in place of the 16's?

Will I need to do anything else to get both tanks operating with the new auxiliary in-tank fuel pump? Thanks!

[Captkaos]

Unless the tanks are bad I wouldn't do this.  When my baffled tanks get low and you are braking (depending on the terrain) mine will stall.

Are you sure you long bed has 2 16g tanks?
They will use the same brackets, just in different places.

[88marmon]

When your truck stalls, how low is "low"?? I still have at least 5 gallons left when it stalls the first time. I only get a range of 170 miles or so because of this.

I measured the tanks and they coincide with the 16 gal measurements. When I hit the gas pump, I usually only put in 10-11 gallons to fill up.

Would the frame already be punched for the 20 gallon bracket placement, or would drilling be necessary?

[Captkaos]

About 3-4 depending on the terrain.