4.3 TB on a 5.7 - loss of power?
Thread Starter
CF Beginner
Joined: Dec 2019
Posts: 4
Likes: 1
4.3 TB on a 5.7 - loss of power?
Hey everyone, new guy here.
So a while back I was contending with an issue with my truck (95 k1500 5.7L) where it stalled on me at the grocery store, and it would always start right up but immediately die a couple seconds later. It eventually was found to be the fuel pump, which I replaced. In the process of diagnosing this (before replacing the pump), one of the things we tried was my brother brought the throttle body/injectors/pressure regulator assembly from his 4.3 parts truck and installed it.
It seemed to run pretty good for a while but now I'm getting a lean exhaust CEL (code 44), and the truck runs really sluggishly when you get on the gas. My question is this: could the fact I have a 4.3 TB assembly have anything to do with that? I would put the old 5.7 TB back on, but the problem is that when my brother put the 4.3 one on, he didn't use a line wrench and ended up rounding off the flare nut on one of the fuel lines at the back of the TB.
I REALLY don't want to have to run new fuel line, does anyone know of a special tool or trick I could use to get it off? I'm not sure if an actual line wrench would fit anymore, and I'm hesitant to just use a vicegrips that'll chew it up even further. My only other idea is maybe I can just cut it off and flare a new end on it, but it's a metal line and as far as I know, I don't think I can get any more slack to re-attach it at that point.
Any input would be appreciated. Thanks
So a while back I was contending with an issue with my truck (95 k1500 5.7L) where it stalled on me at the grocery store, and it would always start right up but immediately die a couple seconds later. It eventually was found to be the fuel pump, which I replaced. In the process of diagnosing this (before replacing the pump), one of the things we tried was my brother brought the throttle body/injectors/pressure regulator assembly from his 4.3 parts truck and installed it.
It seemed to run pretty good for a while but now I'm getting a lean exhaust CEL (code 44), and the truck runs really sluggishly when you get on the gas. My question is this: could the fact I have a 4.3 TB assembly have anything to do with that? I would put the old 5.7 TB back on, but the problem is that when my brother put the 4.3 one on, he didn't use a line wrench and ended up rounding off the flare nut on one of the fuel lines at the back of the TB.
I REALLY don't want to have to run new fuel line, does anyone know of a special tool or trick I could use to get it off? I'm not sure if an actual line wrench would fit anymore, and I'm hesitant to just use a vicegrips that'll chew it up even further. My only other idea is maybe I can just cut it off and flare a new end on it, but it's a metal line and as far as I know, I don't think I can get any more slack to re-attach it at that point.
Any input would be appreciated. Thanks
CF Active Member
Joined: Dec 2019
Posts: 233
Likes: 36
The fuel lines are flex lines up to where they switch to metal, there is a hard mount at the rear of the block/intake where they are attached. If you pull that bolt that should allow you some slack. It might be easier to simply change the injectors. I believe the 4.3 and 5.7 use the same TB, just different injectors. Take your 5.7 injectors and swap them in place of the 4.3's and you should be good to go.
Thread
Thread Starter
Forum
Replies
Last Post