My Sierra: swapping from Fuel Injection to Carb - need tips

[Zoomer]

Wanted to post this to receive your general tips & insights on a project. It will be on my 1994 GMC Sierra 4x4 half ton extended cab. The plan is to ditch the fuel injection and rewire the truck for a carb engine.

Looks similar to the truck below.





The engine is tired and needs to be replaced. The truck I want to keep alive so I've put the fate of it in the hands of my close mechanic friend.

He proposed the plan to swap to carbs. I'm all for it, but wanted to first at least get another opinion to see if there are any major pitfalls.

For example, does the transmission on these trucks rely on the computer ? I've heard that on certain vehicles, the tranny relies on the computer and if you want to do a carb swap like this you basically need to get another tranny.

Also I would like your suggestions on aftermarket carbs, manifold, etc - to maximize performance. Since fuel mileage will probably go out the window with this project, I think this truck will end up being more of a toy than anything.

Thanks in advance for your tips & advice.

[ukrkoz]

oy, don't be so desperate on carb mpg! i think, you are entering a wonderful era of being able to, actually, improve your mileage, as carb is not controlled by ECM, like FI engine.
of course, i'm a zany one saying that, but! just go here:
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and then go to "automobiles" section.
YOU WILL HAVE A WORLD OF DESIGNS FOR CARBS! top it with time and good set of hands - and one never knows!

[silverhairdeere]

could have either a 4l60e or a 4l80e or a manual both automatics are computer controlled , why may i ask do you want to go back to carb , if i remember right you may not even have the fuel pump block off plate , which means a electric fuel pump for your carb. i think what ever problems you have with fi should be worked out . also even though you only have a obd1 computer there are many sensors that help the truck run good .just my own opinion

shd

[batty1214]

I agree with silver..... you can pull some serious mileage with the throttle body set up with some minor tuning, and some good parts..... I had mine redone on my 95 gmc 5.0 and Im pulling 20-23 mpg(when not on the go go pedal

[leolkfrm]

welcome to the forum
First question, What are your state inspection requirements? carbs and cats really don't get along. A manual tranny is less problems than the new style electronic auto when converting.
I think in the long run working with what you have may prove easier and cheaper in the long run

[436'd skylark]

you will need a tps signal for the tranny to work. otherwise it will default to limp mode and not shift out of first gear. several companies sell stand alone control kits for the new trannys. not a huge obstacle, but an extra couple hundred bucks none the less.

[bradrhale]

stick with the EFI. i imagine you will be alot happier.

[Zoomer]

Where is the fuse to bypass the computer?

Originally Posted by 436'd skylark

you will need a tps signal for the tranny to work. otherwise it will default to limp mode and not shift out of first gear. several companies sell stand alone control kits for the new trannys. not a huge obstacle, but an extra couple hundred bucks none the less.

Good to know man. Yet what we want to do is just bypass the computer for the engine and keep it for the tranny side. If that's possible then we may be ok.

[mudseeker]

did they have the 60e's in 94 or was that still a cable operated trans?

[silverhairdeere]

according to chilton's both transmission. here is your wiring diagram be careful what you unhook !!
shd