Carb to TBI swap with dual tanks, what's involved in the fuel system swap?

[zero cool]

I did a search but didn't really find out exactly what I was looking for.

I have an 86 K20 with the dual side tanks. I'm running a carburetor right now (of course) but I'm going to be swapping in a new motor. It's going to be a TBI motor since I already have the throttle body, wiring harness and computer.

My question is what all is involved in swapping the fuel system for my dual tank setup?

I'm not seeing a return line in my current setup (either I'm blind or stupid or it's really not there). I know the TBI system needs one.

Can I keep my stock tanks and just buy all of the components to fit a later model TBI equipped truck? Say an 87 or 88? Or is there anything specific to the tanks that I would have to replace them in my truck? Would I need to replace all the lines or just add the return line and get the proper valve that handles a return line in addition to the supply line?

Would it be better to do in tank pumps or put a single inline pump after the switch? I know in tank pumps are more expensive, especially since I'd need two, but not enough to kill the budget.

 

[lak2004]

Hmm well I cant answer much but I know you will need to run your own return line.

 

[dyeager535]

I would say that if you are comfortable having to keep the tanks somewhat filled up, and don't do much for wheeling in it (not much nose up or down) then you could probably continue to run your tanks as is, with the addition of the TBI pumps/sending units.

I would think you'd HAVE to have return lines to the tanks on a truck your vintage, does your fuel pump have three lines on it? One will be return if so. Obviously that one line would be split at the switching solenoid.

Your easiest path overall IMO is going to be finding a 1987 truck identical to yours, and just taking everything off of it for your swap.

In tanks are better. As close to the fuel as possible, which means they run cooler and are more efficient due to pushing almost the entire distance. Longevity should theoretically be longer as well if the two pumps are otherwise identical. If you aren't worried about cost, that's the way I'd do it.

 

[zero cool]

I would say that if you are comfortable having to keep the tanks somewhat filled up, and don't do much for wheeling in it (not much nose up or down) then you could probably continue to run your tanks as is, with the addition of the TBI pumps/sending units.

This won't be intended as a wheeling rig but I may take it out on some easy trails while I'm building my rock crawler.

I would think you'd HAVE to have return lines to the tanks on a truck your vintage, does your fuel pump have three lines on it? One will be return if so. Obviously that one line would be split at the switching solenoid.

Well, I'm going to be swapping engines. It has a junkyard 305 in it right now. The original engine blew up and I swapped in the 305 to get it moving. I'm going to be building up a TBI 454 to drop in when I'm ready. So basically nothing from the fuel system will come with the swap. Besides, you can't run TBI off a mechanical pump (what my 305 has) anyway.

Your easiest path overall IMO is going to be finding a 1987 truck identical to yours, and just taking everything off of it for your swap.

That may be the best choice. If I can find one with dual tanks that is.

In tanks are better. As close to the fuel as possible, which means they run cooler and are more efficient due to pushing almost the entire distance. Longevity should theoretically be longer as well if the two pumps are otherwise identical. If you aren't worried about cost, that's the way I'd do it.

Well, I don't want to say I'm not worried about cost. But I don't want to just throw money at it for no reason.

 

[slyguy_22]

Check this out it might help
http://store.summitracing.com/egnsearch.asp?N=700+115+%2D160448&D=%2D160448

 

[zero cool]

Check this out it might help
http://store.summitracing.com/egnsearch.asp?N=700+115+%2D160448&D=%2D160448

That's exactly what I need. A few tubing pieces for the return and I should be good to go. Thanks.

 

[Jason4x4]

I did it on mine, I had a return line already, I kept the oe tanks till I put a hole in 1 then I replaced them with the 87 tanks from rock auto. I put this pump, http://www.aztpi.com/product.php?productid=44&cat=1&page=2, it is pricey, but they are in town and do it all the time and they said this a a really good pump,(they actually said they had a customer put one in the engine compartment and it didn't have any problems). I put it just after the switching valve so that I wouldn't need to buy 2, and they also sell just the pump, but I learned the hard way by destoying one of those to run the pre filter, I got some really bad gas on the way to blazer bash.
If you have any other questions, feel free to ask, I can even get pics if you need them.