Restoring the two has tanks
 

Hi I have a 86 I just got after my 81 was stolen this one has two tanks on it like the old 81 but the driverside tanks is not working from the switch I have no experience with the tanks but don't think it's a hard job to trouble shoot and fix my self with some no how so hear goes anyone have some no how this is a TBi injected c10 not like my 81 was and I'm sure that system works electricly what should I be checking and what's the parts the come n play with this system
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Re: Restoring the two has tanks
 

If you have an 86 and someone has converted it over to TBI there is no real telling where the issue is they might not have put a fuel pump in both tanks or replaced both tanks with TBI tanks or it might have an inline fuel pump instead which is simpler when converting them over so first thing you need to do is figure out the fuel delivery setup and see if you're dealing with two fuel pumps or just one or maybe one tank is simply not hooked up since it was made for a carb and is now running TBI or it could be something as simple as a switch on the dash not letting it switch from one to the other for sure you will have to get to the basics first and expand out sometimes is more of a problem finding the problem than fixing the problem let us know what you find

Re: Restoring the two has tanks
 

What's the build date? I remember reading somewhere that some of the really late 86 builds got the 1987 TBI setup. Don't know if it's true...

I'd check the switch first. GM used some really cheap polarity reversing rocker switches. I usually replace them with a DPDT ON-ON toggle switch.

Make sure the switching valve is in place and plumbed into the fuel lines.
Check for a frame mounted fuel pump... This would've been installed by someone converting to TBI "on the cheap". If it's between the engine and the valve it should not be affected by switching tanks. If they installed a TBI tank and sender they might've only installed one.

I attached links to my scans of the 1986, 1987, & 1989 GM schematics.


1986 GM CK Light Truck Wiring Manual
1987 GM RV Light Truck Wiring Manual
1989 GM RV Light Truck Wiring Manual

Re: Restoring the two has tanks
 

Thanks i think I need to start hear first I got this truck on criags list the truck is crazy the cab is from a 81 the front clip say 86 the 350 has tbi the trans is 700r4 I think it's a 5.7l so with that said I think my first and hardest step is that I need to figure out what the H I have on my hand find and run the Vin for everything smh will update on that soon
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Re: Restoring the two has tanks
 

Sounds like Baron Frankenstein was the PO. IT'S ALIVE!!! :lol:

Re: Restoring the two has tanks
 

Ok talk to the dude I got the truck from and it seems it's not as bad as I was thinking this was a true 1986 but a tree hit the hood and he replace the hold cab not a big deal no where I do have a problem is the throttle body and like most people I no I have no idea how this system work to no what's wrong I'm getting smoke out the pipes and the throttle body makes a hissing sound sometimes always at cold start this dude plugged all emissions stuff off I will send linkes to pics of this miss tomorrow I'm going to clean the tbi but have no idea how the electrical parts work and what wires to check on the top of the minfold
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