TBI Conversion Fuel Tank Options

[MtBraun]

Hello - new to the forum. Thanks for the great resource!

I have a 78 K15 with a 350 that my son and I are in the process of converting to TBI. We found a 1991 Chevy donor truck and have begun stripping everything we need. My question is on fuel tanks. I want to convert to an updated TBI tank with baffles and in tank pump. Has anyone fitted a TBI side-frame tank to a square body? If so, how does it fit?

Another option may be to use a Suburban tank. I like this option as it is a bigger tank and will distribute weight better for our use (primarily snowplowing). If I go the 'burb tank route, will the pump from our 91 donor truck fit this tank? I'm not sure I can find a good used tank from a 'burb so may just buy a new tank since they are only $100.

 

[Azathoth]

I think the 91 tank is different since they moved them to inside the frame rails. You can use an 87 tank. They are drop in and you can even run dual tanks, you will have to come up with wiring. There is a member on here who makes harnesses for dual tanks set ups. Do you have a 2 or 3 line sending unit now? FI sending units are 3 line, that's the only hiccup. Rock Auto lists the same part number for 87 and 91 truck pumps. Do you really want to have the tank out and not put in a new pump?

 

[4WDKC]

Hello - new to the forum. Thanks for the great resource!

I have a 78 K15 with a 350 that my son and I are in the process of converting to TBI. We found a 1991 Chevy donor truck and have begun stripping everything we need. My question is on fuel tanks. I want to convert to an updated TBI tank with baffles and in tank pump. Has anyone fitted a TBI side-frame tank to a square body? If so, how does it fit?

Another option may be to use a Suburban tank. I like this option as it is a bigger tank and will distribute weight better for our use (primarily snowplowing). If I go the 'burb tank route, will the pump from our 91 donor truck fit this tank? I'm not sure I can find a good used tank from a 'burb so may just buy a new tank since they are only $100.

Buy a tank for an 87 its the first year for the TBI in half ton and it is a square body, other options would be pulling a tank from an 87-91 crewcab truck as they are still squarebodied and fuel injected. In all honesty you would probably be better off buying a new tank for an 87 so you wont have to worry about rust or having it cleaned. The 88+ regular cab trucks have the gas tanks mount inside the frame, possible dont have the shape to clear the floor of the cab/bed etc. on the squarebody trucks. While you're at it buy an ep241 or ep387 fuel pump so you wont have to upgrade it later if needed.

As far as the burban tank, how would you fill it? A filler neck in the bed, I think it is bad for a truck that will be used as a truck. If you have the bed full of salt in your case do you want to have to move it to fill the tank?

 

[Maaac1789]

What they said

 

[MtBraun]

Buy a tank for an 87 its the first year for the TBI in half ton and it is a square body, other options would be pulling a tank from an 87-91 crewcab truck as they are still squarebodied and fuel injected. In all honesty you would probably be better off buying a new tank for an 87 so you wont have to worry about rust or having it cleaned. The 88+ regular cab trucks have the gas tanks mount inside the frame, possible dont have the shape to clear the floor of the cab/bed etc. on the squarebody trucks. While you're at it buy an ep241 or ep387 fuel pump so you wont have to upgrade it later if needed.

As far as the burban tank, how would you fill it? A filler neck in the bed, I think it is bad for a truck that will be used as a truck. If you have the bed full of salt in your case do you want to have to move it to fill the tank?

Thanks for the suggestion. I will check out the 87 tank as I'm not interested in taking a chance on a used tank. Is the 87 tank baffled? I have read issues with the older square body tanks causing fuel starvation issues because of the lack of baffles. Are the pumps noted above plug and play with the stock 87 tank/pickup unit?

This truck will have a flatbed so filling a rear mounted 'burb tank would be easy. I would flush mount a door in the bed to access the filler neck. The other positive is that I can get a 31 gallon 'burb tank as opposed to a 20 gallon stock replacement tank without having to mess with dual tanks. Just some thoughts.

 

[4WDKC]

Thanks for the suggestion. I will check out the 87 tank as I'm not interested in taking a chance on a used tank. Is the 87 tank baffled? I have read issues with the older square body tanks causing fuel starvation issues because of the lack of baffles. Are the pumps noted above plug and play with the stock 87 tank/pickup unit?

This truck will have a flatbed so filling a rear mounted 'burb tank would be easy. I would flush mount a door in the bed to access the filler neck. The other positive is that I can get a 31 gallon 'burb tank as opposed to a 20 gallon stock replacement tank without having to mess with dual tanks. Just some thoughts.

My concer for the burban tank was what if your salt spreader covers the filler door? Yes they are direct plug ins I have one a tank now and will do the other soon. I like the idea of dual tanks just so if one pump goes out you have another to get around on till you can fix the first one. There is something in the bottom the fuel gets routed in but its not like newer tanks with a bladder around the sending unit. I was going to suggest something like this https://www.holley.com/products/fuel_systems/hydramat/hydramats/parts/16-106 but, for that price I think I would try and adapt a bladder from a newer sending unit.

 

[MtBraun]

My concer for the burban tank was what if your salt spreader covers the filler door? Yes they are direct plug ins I have one a tank now and will do the other soon. I like the idea of dual tanks just so if one pump goes out you have another to get around on till you can fix the first one. There is something in the bottom the fuel gets routed in but its not like newer tanks with a bladder around the sending unit. I was going to suggest something like this https://www.holley.com/products/fuel_systems/hydramat/hydramats/parts/16-106 but, for that price I think I would try and adapt a bladder from a newer sending unit.

No salt spreader on this truck. Very few, if any of the private plowers in this neck of the woods use salt. That bladder is a neat idea, but like you inferred it is cost prohibitive for this project. I was able to find a Dorman (576-336) tank for the 87 that says it is baffled. If I go this route I will just source a new sending unit and pump and be done with it.

 

[4WDKC]

No salt spreader on this truck. Very few, if any of the private plowers in this neck of the woods use salt. That bladder is a neat idea, but like you inferred it is cost prohibitive for this project. I was able to find a Dorman (576-336) tank for the 87 that says it is baffled. If I go this route I will just source a new sending unit and pump and be done with it.

Rockauto is where I got my sending unit and you can make sure you get the delco only ep241 or ep387(may need modification)

 

[fussfeld]

Will the stock TBI sending unit and original type fuel pump fit in a pre-87 1/2 ton's tank?

 

[foamypirate]

Will the stock TBI sending unit and original type fuel pump fit in a pre-87 1/2 ton's tank?

They will, but not recommended, since you won't have baffles to prevent fuel starvation when low on fuel and braking and/or cornering.

 

[rpcraft]

the upside is you can get a gas tank for cheap off Amazon, Ebay, or even rock auto. I paid about 90 USD for mine, shipped. That was a K5 30 gallon tank though so I am not sure what a truck tank will end up costing. Probably about the same.

 

[fussfeld]

What's the best intank fuel pump regardless of price?

 

[CSFJ]

What's the best intank fuel pump regardless of price?

I put a Delphi in My '88 K1500 a couple years ago. Got it from Summit iirc. One of the more expensive options, but I'm thinking that they were one of the original suppliers.

 

[yevgenievich]

What's the best intank fuel pump regardless of price?

I have used ac Delco and walbro pumps with good success

 

[rpcraft]

In i might ask what is a K15 GM product?