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Old 10-17-2019, 02:02 PM   #1
raidmagic
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Dual tank question

Can someone tell me or link me to an article that explains how the dual tank system works? I have an 80 and only the right tank works. The guy I bought it from told me the left doesn't work and I haven't tried it because I want to look in it first to make sure there isn't a bunch of crap in it.
Anyway what I'm interested in is how the switch over works and what to look for that would cause the left tank not to work. It has a mechanical fuel pump on the engine so I know that's not the issue. What else to look for?

Thanks
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Old 10-17-2019, 05:57 PM   #2
hatzie
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Re: Dual tank question

You mean this writeup?
http://67-72chevytrucks.com/vboard/s...d.php?t=754061

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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...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.
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Old 10-17-2019, 09:07 PM   #3
raidmagic
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Re: Dual tank question

Perfect. How did you find that? I am terrible at searching this stuff.
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Old 10-17-2019, 09:14 PM   #4
SunSoaked
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Talking Re: Dual tank question

Quote:
Originally Posted by raidmagic View Post
Perfect. How did you find that? I am terrible at searching this stuff.
Because hatzie is the **** on this site. An electrical God! Never doubt hatzie.
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Old 10-17-2019, 09:45 PM   #5
Dleslie212
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Re: Dual tank question

Quote:
Originally Posted by raidmagic View Post
Can someone tell me or link me to an article that explains how the dual tank system works? I have an 80 and only the right tank works. The guy I bought it from told me the left doesn't work and I haven't tried it because I want to look in it first to make sure there isn't a bunch of crap in it.
Anyway what I'm interested in is how the switch over works and what to look for that would cause the left tank not to work. It has a mechanical fuel pump on the engine so I know that's not the issue. What else to look for?

Thanks
I just went thru the exact same thing on my 77 last month. Passengers side tank hadn’t been used in 20 years the guy said. I ended up dropping both tanks and replacing both sending units, and the switching valve. I converted from the single wire six port to the five wire six port. Advice - don’t even bother looking for the single wire style anymore, I tried for weeks to find one. Everything I needed was in the thread Hatzie linked. It wasn’t too bad at all, and this is coming from somebody that is god awful at electrical stuff
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Old 10-18-2019, 08:44 AM   #6
hatzie
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Re: Dual tank question

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Originally Posted by SunSoaked View Post
Because hatzie is the **** on this site. An electrical God! Never doubt hatzie.
That's a heck of an ego boost.
Ray McAvoy is really really good too and there are several other guys that post on this board that know their stuff.

Quote:
Originally Posted by Dleslie212 View Post
I just went thru the exact same thing on my 77 last month. Passengers side tank hadnít been used in 20 years the guy said. I ended up dropping both tanks and replacing both sending units, and the switching valve. I converted from the single wire six port to the five wire six port. Advice - donít even bother looking for the single wire style anymore, I tried for weeks to find one. Everything I needed was in the thread Hatzie linked. It wasnít too bad at all, and this is coming from somebody that is god awful at electrical stuff
I'm darn happy that writeup was able to demystify that system. That's what I was trying to do. Thanks for the good word.
__________________
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...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.
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Old 10-19-2019, 08:04 PM   #7
raidmagic
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Re: Dual tank question

Quote:
Originally Posted by Dleslie212 View Post
I just went thru the exact same thing on my 77 last month. Passengers side tank hadnít been used in 20 years the guy said. I ended up dropping both tanks and replacing both sending units, and the switching valve. I converted from the single wire six port to the five wire six port. Advice - donít even bother looking for the single wire style anymore, I tried for weeks to find one. Everything I needed was in the thread Hatzie linked. It wasnít too bad at all, and this is coming from somebody that is god awful at electrical stuff
In his link he said the 6 port was hard to find, where did you get yours? I've got a parts truck so I'll try the two I have and then start the search if they don't work. I've got to do my drivetrain swap first then this is the next thing I'm going to tackle.
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Old 10-19-2019, 08:18 PM   #8
Dleslie212
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Re: Dual tank question

Quote:
Originally Posted by raidmagic View Post
In his link he said the 6 port was hard to find, where did you get yours? I've got a parts truck so I'll try the two I have and then start the search if they don't work. I've got to do my drivetrain swap first then this is the next thing I'm going to tackle.
I ended up converting to the six port five wire style, and running a new switch and wiring. I bought the vakve, pigtail and switch on Amazon.
Pigtail -


https://www.amazon.com/your-orders/p...ntId=DH2nk4Jw2

Switch -
https://www.amazon.com/your-orders/p...ntId=DBfDSsYKL

Last edited by Dleslie212; 10-19-2019 at 08:24 PM. Reason: Added links
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Old 10-20-2019, 12:33 PM   #9
hatzie
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Re: Dual tank question

The early model 73-80 single wire six port solenoid valve is hard to find.

The later model 81-91 five wire (six position connector) motorized six port valve is really easy to find.
Converting from the early to the later model valve isn't that difficult.
__________________
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...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.
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Old 10-20-2019, 12:36 PM   #10
Dleslie212
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Re: Dual tank question

Quote:
Originally Posted by hatzie View Post
The early model 73-80 single wire six port solenoid valve is hard to find.
I'd say damn near impossible to find... I literally tried for about two weeks. I found a couple of places that had them listed, but they were always just the wrong picture for the five wire style
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Old 10-20-2019, 01:57 PM   #11
hatzie
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Re: Dual tank question

Quote:
Originally Posted by Dleslie212 View Post
I'd say damn near impossible to find... I literally tried for about two weeks. I found a couple of places that had them listed, but they were always just the wrong picture for the five wire style
I've found plenty of that kind of bait n switch stuff.
They're loooong obsolete.
__________________
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...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.
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Old 10-20-2019, 09:18 PM   #12
raidmagic
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Re: Dual tank question

Quote:
Originally Posted by Dleslie212 View Post
I ended up converting to the six port five wire style, and running a new switch and wiring. I bought the vakve, pigtail and switch on Amazon.
Pigtail -


https://www.amazon.com/your-orders/p...ntId=DH2nk4Jw2

Switch -
https://www.amazon.com/your-orders/p...ntId=DBfDSsYKL
Quote:
Originally Posted by hatzie View Post
The early model 73-80 single wire six port solenoid valve is hard to find.

The later model 81-91 five wire (six position connector) motorized six port valve is really easy to find.
Converting from the early to the later model valve isn't that difficult.


Ah ok, thanks. I misread that part.
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