Author Topic: 1989 V3500 fuel selector valve  (Read 3742 times)

Offline kjnmontana

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1989 V3500 fuel selector valve
« on: June 21, 2020, 07:13:51 PM »
The current location of the fuel tank selector valve on my 89 dual tank V3500 former tow truck is incredibly hard to access and replace. I have a ton of room behind the cab bench seat to install the valve and route the fuel lines from each tank forward to the mechanical fuel pump using flexible fuel hosing. I’m looking for feedback on why this should or should not be a doable thing. Thanks
« Last Edit: June 22, 2020, 01:02:00 AM by bd »
KJ

Offline bake315

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Re: 1989 V3500 fuel selector valve
« Reply #1 on: June 21, 2020, 07:38:27 PM »
In line with this thread, the current location of the fuel tank selector valve on my 89 dual tank V3500 former tow truck is incredibly hard to access and replace. I have a ton of room behind the cab bench seat to install the valve and route the fuel lines from each tank forward to the mechanical fuel pump using flexible fuel hosing. I’m looking for feedback on why this should or should not be a doable thing. Thanks

It sounds like you’re talking about relocating the selector valve itself inside the cab.  If this is what you’re thinking, I think it would be an unwise choice.  I would try to find somewhere - anywhere - other than in the cab. 
• '73 Cheyenne Super C20 454/400 http://forum.73-87chevytrucks.com/smforum/index.php?topic=7672.0
• ’79 Scottsdale K10 350/NP208/SM465 “Oscar” http://forum.73-87chevytrucks.com/smforum/index.php?topic=37885.0
• ’87 Custom Deluxe R30 350/400 “Felix”

Offline kjnmontana

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Re: 1989 V3500 fuel selector valve
« Reply #2 on: June 21, 2020, 11:19:34 PM »
Thanks for the reply, that’s my problem, a short bed with saddle tanks, mufflers and box cross members makes it hard to find a protected, accessible, not exposed to exhaust heat location, thus the cab, which in my Mad Max thinking, could be an option, as it would be protected and if properly plumbed, reasonably safe. The original location was insane and probably the reason the previous owner bypassed it and only used one direct feed tank.
KJ

Offline bd

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Re: 1989 V3500 fuel selector valve
« Reply #3 on: June 22, 2020, 12:59:49 AM »
You hit the nail squarely on its head with your Mad Max reference.  LOL

Fuel lines should never be routed above or into/through a passenger compartment or enclosed storage area under any circumstances.  The potential for hazardous leaks, fuel vapor accumulation, occupant exposure to toxic vapors, and fire make the "convenience" of relocating the selector valve inside the cab exceedingly risky and jeopardizes the safe operation of a vehicle.  In addition, a modification of that nature might nulify insurance coverage in the event of a fire, not to mention, the question of legality; it certainly is illegal with regard to buses.

Replacing a fuel selector valve mounted in its factory location inside the right frame rail is a trying nuisance the first time through, but certainly is doable, as many thousands of people can attest.  I've replaced dozens of valves.  Not fun but achievable and easier with each replacement.

1989 Service Manual
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 VileZambonie

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Re: 1989 V3500 fuel selector valve
« Reply #4 on: June 22, 2020, 07:10:12 AM »
Not to mention personal liability if anything ever were to happen to an occupant as a result of your "modification"

Yeah they're a pain to service but luckily don't require frequent service.
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74 GMC, 75 K5, 84 GMC, 85 K20, 86 k20, 79 K10

Offline kjnmontana

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Re: 1989 V3500 fuel selector valve
« Reply #5 on: June 22, 2020, 08:33:32 AM »
Thanks for the replies folks, they’re the reason I joined this group as I can talk myself into anything!
I’ve also got a post regarding wiring harnesses that if you’ve the time to comment it would be appreciated.
KJ

Offline kjnmontana

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Re: 1989 V3500 fuel selector valve
« Reply #6 on: June 22, 2020, 08:36:36 AM »
BD, thanks for the digital manual, priceless.
KJ

Offline bake315

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Re: 1989 V3500 fuel selector valve
« Reply #7 on: June 22, 2020, 11:57:00 AM »
Thanks for the reply, that’s my problem, a short bed with saddle tanks, mufflers and box cross members makes it hard to find a protected, accessible, not exposed to exhaust heat location...

If you are worried about exposure to exhaust heat, you might consider fashioning a heat shield from a piece of sheet metal that could be placed between the valve and the heat source (my ‘87’s valve has a protective shield over it from the factory).  You could fashion something similar, and line it with header wrap so that heat would no longer present an issue. Such a shield would also protect the valve from rocks and road debris.
« Last Edit: June 22, 2020, 11:58:49 AM by bake315 »
• '73 Cheyenne Super C20 454/400 http://forum.73-87chevytrucks.com/smforum/index.php?topic=7672.0
• ’79 Scottsdale K10 350/NP208/SM465 “Oscar” http://forum.73-87chevytrucks.com/smforum/index.php?topic=37885.0
• ’87 Custom Deluxe R30 350/400 “Felix”

Offline kjnmontana

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Re: 1989 V3500 fuel selector valve
« Reply #8 on: June 22, 2020, 01:53:06 PM »
Thanks Bake, I’ll need to trade my meat hooks in for raccoon paws...the original installation is tight to say the least.
KJ

Offline kjnmontana

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Re: 1989 V3500 fuel selector valve
« Reply #9 on: July 07, 2020, 04:56:58 PM »
After laying on my shop floor under my 1989 V3500 for a few days I’ve realized swapping the valve block is not as imposing as I thought.
I do have a few questions that I hope folks can guide me on.
Background: 1989 V3500, carbureted big block with a mechanical fuel pump.
I’m replacing the RH saddle tank, both sending units, valve block and transfer switch.
My understanding is that the fuel tank transfer switch needed with a carbureted motor is the “Depress Fully” switch vice the toggle, is this correct?
My other question is with regard to the NL2 dual tank system and the use of a sub-harness that plugs into the RH tank sender wire on the RH frame rail with power coming from the fuse panel under the dash.
Is there an illustration of what the sub-harness looks like and how it is wired?
It appears I have the molded pin connector wired into the fuel gauge wire, but the other end was cut from wherever it was suppose end, so I’m not clear on how that should rewired.
Appreciated any direction.
KJ
KJ

Offline JohnnyPopper

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Re: 1989 V3500 fuel selector valve
« Reply #10 on: July 07, 2020, 08:21:31 PM »
This thread was going so nicely...Why did you have to geek out?

The real problem is your truck us 'too new'...check the URL ::)
















I'm sure someone will come to your aid, I got nothin... ???

1957 Apache 3100 235 Inline 6, 3 on the tree
1973 C-20, 3+3 454 4BBL TH400  Water Injection
1978 K-10, 350 4BBL TH350 NP203 M.M. Part time Kit/Hubs
1980 C-10 under construction

Offline kjnmontana

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Re: 1989 V3500 fuel selector valve
« Reply #11 on: July 07, 2020, 10:11:55 PM »
Yep, wasn’t sure how 73-87 url would work for me, but it’s the closet resource, and frankly it appears to be pretty close to what I’m dealing with on my truck.
KJ

Offline JohnnyPopper

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Re: 1989 V3500 fuel selector valve
« Reply #12 on: July 07, 2020, 10:40:21 PM »
You'll find plenty of love here 8)
1957 Apache 3100 235 Inline 6, 3 on the tree
1973 C-20, 3+3 454 4BBL TH400  Water Injection
1978 K-10, 350 4BBL TH350 NP203 M.M. Part time Kit/Hubs
1980 C-10 under construction

Offline bd

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Re: 1989 V3500 fuel selector valve
« Reply #13 on: July 08, 2020, 12:38:21 AM »
My understanding is that the fuel tank transfer switch needed with a carbureted motor is the “Depress Fully” switch vice the toggle, is this correct?
My other question is with regard to the NL2 dual tank system and the use of a sub-harness that plugs into the RH tank sender wire on the RH frame rail with power coming from the fuse panel under the dash.
Is there an illustration of what the sub-harness looks like and how it is wired?


The "DEPRESS FULLY" switch was for pre-87 models.  You need an AC Delco D7089C selector switch. 



The NL2 sub-harness is represented by the colored lines within the red outline in the image below.  On a single-tank system, pink circuit 30 that runs rearward along the right framerail from the bulkhead connector would attach directly to the left (production) fuel tank.  On the dual-tank system, circuit 30 plugs into the NL2 sub-harness as shown in the diagram.
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 VileZambonie

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Re: 1989 V3500 fuel selector valve
« Reply #14 on: July 08, 2020, 06:43:08 AM »
What switch is on your truck now? Depress Fully should be the right one for carbureted models.
,                           ___ 
                         /  _ _ _\_
              ⌠¯¯¯¯¯'   [☼===☼]
              `()_);-;()_)--o--)_)

74 GMC, 75 K5, 84 GMC, 85 K20, 86 k20, 79 K10