Restoring the two has tanks - The 1947 - Present Chevrolet & GMC Truck Message Board Network

Tonio327 · 09-30-2012, 03:27 AM

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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RandyP · 09-30-2012, 12:08 PM

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

**hatzie** · 09-30-2012, 01:23 PM

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

Tonio327 · 09-30-2012, 09:38 PM

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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**hatzie** · 09-30-2012, 11:13 PM

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

Tonio327 · 10-15-2012, 04:06 AM

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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09-30-2012, 03:27 AM	#1
Tonio327 Registered User Join Date: Jan 2012 Location: Atlanta georgia Posts: 20	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 Posted via Mobile Device

09-30-2012, 12:08 PM	#2
RandyP Getting Old; Going Broke Join Date: Apr 2010 Location: Owasso OK Posts: 2,764	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 __________________ *Why is every used 350 sbc out of a corvette?* There's only two things that excite a man, expensive toys and real expensive toys. *VEGETARIAN: That's an old Indian word meaning "I don't hunt so good."* When the going gets tough, switch to power tools.

09-30-2012, 01:23 PM	#3
hatzie Moderator Join Date: Oct 2008 Location: Wentworth, NH Posts: 4,977	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 __________________ 1959 M35A2 LDT465-1D SOLD 1967 Dodge W200 B383, NP420/NP201 SOLD 1969 Dodge Polara 500 B383, A833 SOLD 1972 Ford F250 FE390, NP435/NP205 SOLD 1976 Chevy K20, 6.5L, NV4500/NP208 SOLD 1986 M1008 CUCV SOLD 2000 GMC C2500, TD6.5L, NV4500 2005 Chevy Silverado LS 2500HD 6.0L 4L80E/NP263 2009 Impala SS LS4 V8 RTFM... GM Parts Books, GM Schematics, GM service manuals, and GM training materials... 1973-1991 GM Light Truck Service, Unit/Overhaul, Wiring Manuals, Parts Books and Some 1968-1999 GM Service Training textbooks in PDF 1988-1998 GMT400 CK service manual project 1988-1993 GMT400 CK parts books. 1967-1972 GM Light, Medium, & Heavy Truck Service Manuals in PDF Please include at least the year and model in your threads. It'll be easier to answer your questions. And please let us know if and how your repairs were successful.

09-30-2012, 09:38 PM	#4
Tonio327 Registered User Join Date: Jan 2012 Location: Atlanta georgia Posts: 20	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 Posted via Mobile Device

09-30-2012, 11:13 PM	#5
hatzie Moderator Join Date: Oct 2008 Location: Wentworth, NH Posts: 4,977	Re: Restoring the two has tanks Sounds like Baron Frankenstein was the PO. IT'S ALIVE!!! __________________ 1959 M35A2 LDT465-1D SOLD 1967 Dodge W200 B383, NP420/NP201 SOLD 1969 Dodge Polara 500 B383, A833 SOLD 1972 Ford F250 FE390, NP435/NP205 SOLD 1976 Chevy K20, 6.5L, NV4500/NP208 SOLD 1986 M1008 CUCV SOLD 2000 GMC C2500, TD6.5L, NV4500 2005 Chevy Silverado LS 2500HD 6.0L 4L80E/NP263 2009 Impala SS LS4 V8 RTFM... GM Parts Books, GM Schematics, GM service manuals, and GM training materials... 1973-1991 GM Light Truck Service, Unit/Overhaul, Wiring Manuals, Parts Books and Some 1968-1999 GM Service Training textbooks in PDF 1988-1998 GMT400 CK service manual project 1988-1993 GMT400 CK parts books. 1967-1972 GM Light, Medium, & Heavy Truck Service Manuals in PDF Please include at least the year and model in your threads. It'll be easier to answer your questions. And please let us know if and how your repairs were successful.

10-15-2012, 04:06 AM	#6
Tonio327 Registered User Join Date: Jan 2012 Location: Atlanta georgia Posts: 20	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 Posted via Mobile Device



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