TBI350 to L31 swap. I'm told close to impossible.

[docstoy]

Couple of other things , if doing dash swap your going from a round column to a square column and the wiring thru firewall look to be different also , not sure what else you will run into. Reason I know about your different years , I've got a '97 c3500 sitting next to my '93 k2500

 

[Sean Buick 76]

Easy swap take all the wiring from the engine to the dash!

 

[yeobee]

The donor 98 was my sons. His pride and joy. He got hit hard enough to spin that beast 90+ degrees. Obliterated the other vehicle...which for some reason and regard was rebuilt. Everyone was still vertical and nobody went to the hospital. I almost sent GM a thank-you card.

The truck is complete...minus the headlights, turns and grill which are on the Yukon now. I have 2 other TBI trucks I can stare at for any befores. The wrecked 98 is the only one close I can touch. There would be plenty of pics, videos, tags, tape and notes before I even grabbed a wrench. I hadn't considered the engraver, but I do have one. I'm getting older and my short term memory is getting thin. I may even completely remove the body since it's sitting in the dirt and I can't quite figure out where to chain the hoist to the engine anyway, heh. Something tells me I'm getting all stressed out when all I really need is some time, a couple gallons of coolant and a few bolts and nuts. Desert climate for the win.

Valid points with the dash and column. I guess I could swap the column but the there's ignition, turn, wiper, hazard things I haven't even contemplated. I'll probably leave the dash alone for now.

I'd like to get the ABS delete done on the Yukon first. It seems to function fine, I just absolutely can't stand the sight of that medusa thing.

As always, this place is a great resource. Appreciate the support.

 

[yeobee]

I've searched this forum to try and find this answer without much luck, so I'll ask on this thread since it's related.

Fuel pump.

Instead of swapping pumps, I'd like to go new, with ideally a new sending unit. I haven't touched the 93 Yukon yet so it still has the TBI pump...or so I'd assume. Only had the truck a few months.

I'm finding pumps with 255lph and 340lph. I'm finding sending units with the TBI pump installed. Kneejerk says get the sending unit with the TBI pump and swap in the 340lph. Is this thinking correct? Unless there is a specialty site that sells the sender with the higher PSI pump. I'd only like to do this once and be done back there.

I'm also curious if the senders are different depths because of the rear tank versus the side saddles.

Thanks all.

 

[Supercharged111]

Is the sending unit crusty? If not, there's zero reason to change it. You'll want a stock AC Delco pump, a 340 is insane overkill for a stock motor. Even a 255 is, but the bigger concern with the 255 is there are knockoffs everywhere. Stock is more than enough, you'll want a pump for a 96-97 350 Vortec.

 

[Komet]

255lph pump is good for 500hp to the wheels, I think a 340lph is totally unnecessary for anywhere near stock motors and it'll end up being extra stress on the electrical system and fuel lines just to circulate the fuel into the tank faster.

You can just swap pumps on your existing fuel sender if it's still good. I used a Racetronix RXP269E 255lph pump to replace the stocker in my '92 K2500. It's too much pump but my system is boost ready, which is important so you can brag about being boost ready.

 

[tayto]

put a carb intake on it and get an adapter plate for TBI. obviously to get the most out of it a tune is required. since you have manual trans your ecu is the older type so a prime candidate for EBL Flash

 

[yeobee]

I'm doubting the sender could be too crusty. Truck runs fine for the few miles I've put on it. It's lived in a dry climate it's whole life, which doesn't say much for the gas that's been dumped in it. With 350K on it, I'm leery. I have very limited history with this rig, but it does appear someone has wrenched on the tank skidplate at least once. I haven't touched it so I'd rather have a new sender just in case. I might grab a new ring for the exact same reason. Local stores want an arm for these which I really want to avoid. I have other 400s so a spare sender on a shelf could be more of a benefit than not. I changed a pump in a 97 Yukon I had once. Quite the straightforward process. I just want all the proper parts in my hand before I grab a wrench.

I'll avoid all the aftermarket pumps. Like I said, I only want to do this once and move to the front stuff. I did the visual mental math on the 255 and 340s. I may grab one if I ever need a sprinkling system booster. Heh. This Yukon will be a part time mountain camper and maybe a Friday or two to work. I have zero plans for any HP upgrades so far. Donor truck ran (still does) like a mashed cat. My first thought was just swapping the pumps, but the donor might have to drag itself to a slightly better location before parts get pulled. The Yukon may end up trailering the engine and tranny to a totally different location for the swap. I'd rather keep both of them running until it's go time.

I did find a sender without the pump. I might just grab that and the delco vortec pump. Already have a new filter. My biggest concern is the Yukon tank is almost full. That's alot of lawnmower fuel.

Appreciate the clarifications.

 

[Firewood truck]

put a carb intake on it and get an adapter plate for TBI. obviously to get the most out of it a tune is required. since you have manual trans your ecu is the older type so a prime candidate for EBL Flash

I'm about to begin a similar swap. My '88 GMC needs a replacement engine. I found a complete L31 that was a low mileage dealer warranty replacement engine. My '88 also has the SM465. I just scored a good '93 NV4500. My approach is to use the L31 like a long block ( and run the vortec accessories) and retain the TBI system by using a GMPP TBI to Vortec intake manifold. ( I scored a screaming deal on one of those a few months ago). As long as the TBI system was working well in your truck ( Yukon?) why not make the swap as easy as possible by adapting the TBI to the vortec heads and be done with it?

 

[yeobee]

The TBI in the Yukon seems strong, just a heavy smoker at temp. The 98 L31 is a goodwrench shortblock that had zero issues.

I'm curious why you would TBI a Vortec? Seems quite a bit more involved.

I'm also curious if you know of any driveline length issues with the 3500/4500 swap.