Author Topic: 86 chev c-10 gas tank HELP  (Read 497 times)

Offline rastafarian

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86 chev c-10 gas tank HELP
« on: January 28, 2014, 07:34:37 PM »
Hi, New to the forum. I bought a 86 chev c-10 long bed with dual gas tanks. When i first got the truck the switch over didn't work so we blocked up the lines and used the right tank for a while. WORKED for a day until it stopped pulling from right tank .... We figured it somehow clogged up the right tank so we then switched it to pull from the left tank only and blocked all the feeds to the right side. Then things start getting weird, while driving it somehow builds up pressure in the lines and starts to shoot out of the cap from the right tank ??? How is that is that possible if the lines are blocked for the right side and where only pulling from the left??? Also it's a mechanical fuel pump , mounted to the block of my 350
« Last Edit: January 28, 2014, 07:38:55 PM by rastafarian »

Offline rastafarian

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Re: 86 chev c-10 gas tank HELP
« Reply #1 on: January 28, 2014, 07:37:36 PM »
 :o
« Last Edit: January 28, 2014, 07:39:27 PM by rastafarian »

Offline dvdswan

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Re: 86 chev c-10 gas tank HELP
« Reply #2 on: January 28, 2014, 08:30:23 PM »
sounds more like the lines are creating a vacuum.  what condition is the evap canister in?

Offline rastafarian

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Re: 86 chev c-10 gas tank HELP
« Reply #3 on: January 28, 2014, 08:49:41 PM »
That's the charcoal  canister  under the hood huh?  Thanks for support!

Online bd

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Re: 86 chev c-10 gas tank HELP
« Reply #4 on: January 28, 2014, 08:53:25 PM »
How many lines connect to each tank pick-up - two or three?
Rich
It's difficult to know just how much you don't know, until you know it....
In other words... if people learn by making mistakes, by now I should know just about everything!!
87 R10 Silverado Fleetside 355 MPFI 700R4 3.42 Locker (aka Rusty, aka Mater)

Offline Boone83K10

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Re: 86 chev c-10 gas tank HELP
« Reply #5 on: January 28, 2014, 08:53:42 PM »
The switching valve is both an electrical and mechanical valve. How did you "switch" it over? The vapor lines from both tanks T into one line that goes to the vapor canister. It could possibly be that.

 

1966 Mercury Comet - Built 429 (First Car/Show Car)
1983 Chevrolet K10 - Built 350 (Winter Toy)
1992 Chevrolet Lumina Euro (Sold @ 265,000 miles)
2003 Ford Escape 4x4 - Mac Perf. Intake/Exhaust (Wifes' DD)
2007 Mercury Milan - Steeda Tuned (Summer Toy)

Offline rastafarian

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Re: 86 chev c-10 gas tank HELP
« Reply #6 on: January 28, 2014, 09:08:13 PM »
I think it's 3 because my Switch over has 6 points on it . And I believe we  switched it over just allowed it to come through the  switch on the left tank port then block all the others with a screw and clamp.

Offline rastafarian

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Re: 86 chev c-10 gas tank HELP
« Reply #7 on: January 28, 2014, 09:10:10 PM »
I also believe it's somehow taking gas from the left and dumping it to the right side. If install a new switch would it fix the problem?

Online bd

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Re: 86 chev c-10 gas tank HELP
« Reply #8 on: January 28, 2014, 09:15:38 PM »
I also believe it's somehow taking gas from the left and dumping it to the right side. If install a new switch would it fix the problem?

That's exactly what it's doing - LOL.  The small 1/4" lines are return lines.  They need to 'switch' along with the 3/8" supply.  Reconnect the 1/4" line from the fuel pump up to whichever tank you are drawing from and your troubles should go away.  Debris in the tanks is another story.  The debris will need to be removed or you'll continue to have intermittent draw problems.
Rich
It's difficult to know just how much you don't know, until you know it....
In other words... if people learn by making mistakes, by now I should know just about everything!!
87 R10 Silverado Fleetside 355 MPFI 700R4 3.42 Locker (aka Rusty, aka Mater)

Offline Boone83K10

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Re: 86 chev c-10 gas tank HELP
« Reply #9 on: January 28, 2014, 10:31:14 PM »
New valve isn't too expensive. It would solve the problem.

 

1966 Mercury Comet - Built 429 (First Car/Show Car)
1983 Chevrolet K10 - Built 350 (Winter Toy)
1992 Chevrolet Lumina Euro (Sold @ 265,000 miles)
2003 Ford Escape 4x4 - Mac Perf. Intake/Exhaust (Wifes' DD)
2007 Mercury Milan - Steeda Tuned (Summer Toy)

Offline rastafarian

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Re: 86 chev c-10 gas tank HELP
« Reply #10 on: January 29, 2014, 12:37:33 PM »
I believe we are connect to the 3/8 and 1/4 return but the switched was hooked up . Would that cause it to build pressure.... Basically will unplugging the switch work??

Offline Boone83K10

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Re: 86 chev c-10 gas tank HELP
« Reply #11 on: January 29, 2014, 01:16:24 PM »
if you are not going to use the selector valve, then you need to run rubber hose from the hard lines on engine side of selector valve to the hard lines coming from whatever tank you are going to use. that would eliminate your problem although the cheap way out. make sure the vapor lines are still hooked up too, they come from both tanks and then T into a single line that runs up to the engine bay.
1966 Mercury Comet - Built 429 (First Car/Show Car)
1983 Chevrolet K10 - Built 350 (Winter Toy)
1992 Chevrolet Lumina Euro (Sold @ 265,000 miles)
2003 Ford Escape 4x4 - Mac Perf. Intake/Exhaust (Wifes' DD)
2007 Mercury Milan - Steeda Tuned (Summer Toy)

 


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