Puzzling truck

[1993GMCC2500SLX]

Have any of you guys ran across one of these gmt 400 tbi trucks with a 5279 305 injector on one side and a 5206 350 injector on the other side?!

 

[PlayingWithTBI]

Have any of you guys ran across one of these gmt 400 tbi trucks with a 5279 305 injector on one side and a 5206 350 injector on the other side?!

Nope, I've only heard of the 4.3L sometimes getting 2 different sizes. I'm thinking someone screwed up when rebuilding it

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[1993GMCC2500SLX]

Nope, I've only heard of the 4.3L sometimes getting 2 different sizes. I'm thinking someone screwed up when rebuilding it

You must be registered for see images attach

Yeah I'm still planning on testing it's fuel pump pressure but I am also beginning to suspect that is the main reason it's backfiring when you give it throttle..

 

[PlayingWithTBI]

Yeah I'm still planning on testing it's fuel pump pressure but I am also beginning to suspect that is the main reason it's backfiring when you give it throttle..

That could actually be "lean popping" out the TBI.

 

[1993GMCC2500SLX]

True I need to look at it again if I remember correctly the injection pod connector that was bare wires was on the passenger side I would almost bet that is the side with the 305 5279 fuel injector If so I should have paid more attention although I am sure I still would have to replace quite a few of those things, because it would not hardly run and before the distributor it wouldn't and stay running.. and the kid I got the truck from keeps telling it's supposed to be 0.40 over didn't say whether it is a stock cam or not...but I have my own theories about all of that, and alot of the stuff on this truck is lack of maintenance not usually an issue with a rebuilt motor.

 

[someotherguy]

Sounds like time to replace those pigtails to the injectors, along with being sure you have the correct injectors installed. A '93 may still have the metal spacer ring between the TBI and air cleaner (they went to plastic around that time - '94-'95 are typically plastic) which can chafe against those wires and cause shorts.

Richard