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'89 R3500 Crew Cab 2wd to 4wd conversion & beyond

Started out with 2wd TBI350 with SM465 to current 4wd with 454, 700r4, NP241

mrk5

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I am assuming you made sure the vent line is clear.

Yeah, but I was wondering if it could be too long too.

Either way, my new plan is to eliminate all the fill after the first rubber elbow and turn that elbow up 90° and stab the fill neck in there.

Screenshot_20211010-190220_Gallery.jpg
 

sweetk30

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I just did my 3500-HD like this and no problem filling at full throttle. The main tank is top inlet with a molded 90* hose .

So i have a 2" 45* then direct to a 2" 90* to around 2ft of straight pipe and then the molded rubber 90* to the tank . The 5/8" vent hose is about the same length that goes on the filler kneck .

20210928_154655.jpg
 

mrk5

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I just did my 3500-HD like this and no problem filling at full throttle. The main tank is top inlet with a molded 90* hose .

So i have a 2" 45* then direct to a 2" 90* to around 2ft of straight pipe and then the molded rubber 90* to the tank . The 5/8" vent hose is about the same length that goes on the filler kneck .

View attachment 392650
My problem is I only have as much rise as yours would if the fill cap was where I drew the red X below.

Screenshot_20211011-122006_Vivaldi.jpg
 

mrk5

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Back on my turn signals. Left/right swap of the LED lights doesn't matter. It works correctly when I put bulbs in the 2 unused sockets. The factory marker lights below the headlights each have 2 sockets and I'm using 1 per side to power the LED lights.

So is the problem that the sockets can't be left empty or putting the bulbs in added resistance? I always thought the lack of resistance was indicated by rapid flashing, but in my case they flash at the correct speed.

As a side note, my diagnosis was a little hampered until I realized one if the bulbs was bad. The filament for the running lights had half fallen off and was laying on the turn signal filament. Glad I noticed that or I would have really been baffled.
 

ktmoutfront

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Just more load is added by the extra bulbs. My turn signal indicaors on the Jimmy are always on when the running/head lights are on. Flash with the powered flasher module.
 

mrk5

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So maybe I do need resistors.

My long term plan is to use the extra sockets to pull wiring to the back of the truck so I can separate out my amber tail lights to be running lights and turn signal only.
 

mrk5

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It's funny my 73 C10 didn't need them. Maybe it's because the wiring is older and creates its own resistance. :rotfl:
 

mrk5

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Here's what I'm trying now. This is just quick and simple using parts/hoses I already have on-hand and didn't have to cut down.

2021-10-13 14.49.54.jpg

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It's just the foot of rubber hose elbow from the saddle tank connected to the original crew cab filler neck. It's about as short and simple as I can make the fill system. If this works I'll do something more permanent.

In looking at the future filler neck options, a question I have came up. Why are there essentially 2 vents on the tank? One is a 1/4" line in the sending unit that runs up to the engine bay and connects to the charcoal canister. The other is a 5/8" line also on the sender that goes to a nipple on the filler neck just below the opening for filler nozzle.
 

mrk5

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If this set up works, one of the filler necks I'm looking at has an unvented cap. Can't find a good answer on if that's a big deal since I have the vent line. I know it would be an issue if the tank had no vent line.
 

Truckman4life

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Should be fine. I ran a diesel tank out of a semi mounted in the bed of a square I had once upon a time. Non-vented cap and they run a vent that is like a check valve and lets air in but not out. I just removed that and put a fuel hose with an inline filter on the end for a tank vent to let it breathe both ways. Your charcoal cannister should work as a tank vent just fine.
 

mrk5

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Cool, because I'm super excited about this filler neck. :D The permanent solution I mean, not what's on there right now.
 
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