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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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You need cruise. Larry and I are working on a way to adapt the GM cruise servo from the late gmt400 trucks and the early cable throttle gmt800 trucks. Needs a vss signal and the signal input from the cruise switch on the turn signal lever.

I'm over simplifying it but based on my quick review of the schematic I think it's possible.
I do have an easy VSS source from the trans controller. I was thinking my buddy's 90 K5 had some sort of vacuum modulator cruise control setup.


You just need a stick between the seat and pedal. Don't over think it.
Snap-on has one with a turn knob for easy adjustments .
Interesting. :thinking:

My other thought is my youngest always comes with me and he just got his learners permit.....

It is really kinda demoralizing. I've spent my whole life enjoying driving places and seeing new things. It's one of the biggest things I like about this hobby we foster on CK5. The thought of not enjoying it is not pleasant. Although it doesn't bother me while I'm driving, but after. Like I mentioned, I could hardly walk yesterday after Saturday's trail running. I even made a point to get out and walk around every chance I had. Today I'm better, but still limping. The hip will bother me at work if I sit for too long. I'm going to look into a standing desk and I probably need to start doing some sort targeted exercises. I was hoping losing weight would help, but it hasn't.


What seats do you have?
They are PRP daily driver seats.

I may have a 4 hour road trip coming up in a different vehicle with cruise control, and I'm curious to see if I have the same outcome.
 

mrk5

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A couple of things confirmed with the gas tank situation.

It is a 40 gallon tank.

I have the correct sending unit.

20211018_142534.jpg

Right now there should be about 35 gallons in the tank. If 95 ohms is full, it should be reading 83 ohms. Using a multimeter on the plug from the sender, it is reading 48 ohms at the plug which should normally equate to 20 gallons. Even if, for some reason, I'm still not able to fill the tank completely, I know for fact I put 29.5 gallons in after the wheeling trip and drove 30 miles which would consume 3 gallons, maybe 4 at the worst. That would put the expected ohms at 60 to 63. I would say the fuel level output is way off.

That on top of running out of fuel 10 gallons shy of an empty tank is leading me to believe I have a faulty sending unit. I'm going to go ahead and pick up a new one and then pull this one out of the tank. I want the new one so I have something to compare to.
 

mrk5

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Forgot one more bit of trail damage from Saturday's trip.

20211018_141447.jpg

Muffler is hanging by wire. :D You can see the hanger literally tore off the bit of muffler pipe. Need to weld it back on with a bit more surface area. Also thinking it might work better if the rod it directly on top so it's not getting twisting stress.
 

mrk5

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I prefer to buy SPECTRA PREMIUM brand tanks and senders .
I do too, and this is Spectra. Which kinda bums me out a little. When I pull it out, it will be interesting to see if anything is physically wrong with it.
 

AJMBLAZER

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I do have an easy VSS source from the trans controller. I was thinking my buddy's 90 K5 had some sort of vacuum modulator cruise control setup.




Interesting. :thinking:

My other thought is my youngest always comes with me and he just got his learners permit.....

It is really kinda demoralizing. I've spent my whole life enjoying driving places and seeing new things. It's one of the biggest things I like about this hobby we foster on CK5. The thought of not enjoying it is not pleasant. Although it doesn't bother me while I'm driving, but after. Like I mentioned, I could hardly walk yesterday after Saturday's trail running. I even made a point to get out and walk around every chance I had. Today I'm better, but still limping. The hip will bother me at work if I sit for too long. I'm going to look into a standing desk and I probably need to start doing some sort targeted exercises. I was hoping losing weight would help, but it hasn't.



They are PRP daily driver seats.

I may have a 4 hour road trip coming up in a different vehicle with cruise control, and I'm curious to see if I have the same outcome.
Considered going to any physical therapy?

I was having issues with my right knee and my doc recommended some PT. I did it for about two months in late summer and now the pain in the knee is (mostly) gone. The problem is your body adapts to the "best way to operate" even if it's causing you pain. You have to sort of re-train it and yourself to operate correctly.
 

skunked

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I'm not surprised the hanger tore off the piping. I usually bend them so they wrap under the pipe and use the rubber isolator on the frame side for some flex.
 

Cheavyk10

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I'm pretty sure I got bunked on a sending unit from Rock Auto. It was the correct part # and everything, but I think it was for a 16 gallon saddle tank, not my 20 gallon. Gauge stays full for a long time then drops to half a tank quick, which I figured out is really about 1/4 tank. I never ohm tested it, I just got used to the quirky reading.
 

mrk5

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Considered going to any physical therapy?

I was having issues with my right knee and my doc recommended some PT. I did it for about two months in late summer and now the pain in the knee is (mostly) gone. The problem is your body adapts to the "best way to operate" even if it's causing you pain. You have to sort of re-train it and yourself to operate correctly.
I am worried about that adapting thing with the way it feels the last 2 days. It's definitely affecting my walk. I'm going to start out with some self-directed therapy type stuff plus get a standing desk setup and see where that gets me.


I'm not surprised the hanger tore off the piping. I usually bend them so they wrap under the pipe and use the rubber isolator on the frame side for some flex.
I does at least have the rubber isolator on the other end. We were re-using an old one that had already been cut down. Sounds like I may need to see if I can find a new rod.


I'm pretty sure I got bunked on a sending unit from Rock Auto. It was the correct part # and everything, but I think it was for a 16 gallon saddle tank, not my 20 gallon. Gauge stays full for a long time then drops to half a tank quick, which I figured out is really about 1/4 tank. I never ohm tested it, I just got used to the quirky reading.
I was ready to accept the bad reading but then when I started losing fuel pump output 10 gallons short of when the tank should be empty I decided I needed to do something about it. I'm real curious to see if something has gone awry, like the pump fell off the sender or something odd like that.
 

ZooMad75

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Spectra has pulled out of the domestic market for fuel tanks, senders and radiators. If you find a new one it might be a knock off as they pulled out last year sometime.

The running out of fuel with 10 gallons left is odd. Almost like the sender isn't reaching the bottom of the tank. Is this a TBI tank with the baffle in it or non TBI with a TBI sender?
 

6872xtc

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Just get the leg stamina of one of us old truck drivers. I've done Junction to Vegas and back with only a 2 hour nap... Big cam 400 Cummins never had cruise control!
:waytogo:
However, that was 20+ years ago.
 

mrk5

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The drive itself isn't an issue, it's the next day when I pay.

Spectra has pulled out of the domestic market for fuel tanks, senders and radiators. If you find a new one it might be a knock off as they pulled out last year sometime.

The running out of fuel with 10 gallons left is odd. Almost like the sender isn't reaching the bottom of the tank. Is this a TBI tank with the baffle in it or non TBI with a TBI sender?
I got my Spectra from Advance Auto Parts earlier this spring. I double checked yesterday, and they aren't in stock anymore.

Matter of fact, I can't find any in stock with the exception of a $190 unit and a $260 sender that includes the TBI fuel pump that I can't use for the aftermarket EFI. RockAuto showed the $57 Brute Power sender in stock so I ordered it yesterday but got notified today they don't actually have one in stock. So it looks like I need to see if I can fix what I have now.

Luckily I'm using the Holley Digital Dash for the fuel level gauge which means I can program the ohms to equal whatever I need. I can use the tester to figure out what ohms full and empty are and program the dash to reflect.

It is a baffled TBI tank. One of the things I want to check is if maybe the baffle tray came loose and it's knocking the fuel pick up and/or pump around. We had to do a trail fix for that one year on Gold Bar Rim with a tank in a Suburban.
 

mrk5

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Well, well, well, if any of you follow @the_blaze's Plan B build thread, this will look quite familiar.

2021-10-19 14.13.20.jpg

A bent sending unit! It looks exactly like the one he pulled from his tank. I definitely did not cave in the bottom of my tank. The drive shaft would be living in the tank if I did.

2021-10-19 14.42.07.jpg

Here's the depth of the tank. It's measured from the long end of the square that starts at 24".

2021-10-19 14.18.09.jpg

2021-10-19 14.18.21.jpg

So it's basically 11-7/8". The bent up sender measures well short of the bottom and about 10-1/4".

2021-10-19 14.29.34.jpg

I can't see any way the tank was sucked or dented in 1-5/8" without any outward indication. I can push down and get minimal movement on the top of the tank, certainly no where near 1-5/8".

I pried on the baffle tray with the square and it's solidly afixed.

2021-10-19 14.31.44.jpg

You can see a mark where the bottom of the sender scraped on the tank.

I could easily bend the tube back to straight and the sender sits down into the tank easily as referenced in the picture below:

2021-10-19 14.32.53.jpg

I could move the locking ring around 3/4 of the way to fully seated by hand. That confirms there is plenty of room between the sender and the bottom of the tank.

The only working theory we've come up with is the tube is so weak it's getting bent by fuel slosh.
 
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Truckman4life

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That is crazy! Definitely couldn't have been caved in with where you have your tank mounted. Looks just like his did.
 

mrk5

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I'm pretty sure it wasn't bent before initial install. It was a big chore to get it out today because of it being bent. I'm pretty sure I would have thought it was odd for the rubber hose between pump and sender tube to be curved.

I'm a little torn about what to do. RockAuto has a Liland Global unit that is expensive, but maybe that means better quality. https://www.rockauto.com/en/moreinfo.php?pk=10197032&cc=1301252&pt=4436&jsn=538

Or I could get a cheap unit from eBay https://www.ebay.com/itm/164443316468 and weld in some gussets to support the bends in the tubing.

In reality those are just about my only 2 choices because there isn't anything else in-stock anywhere I've looked. I guess the third option would be an external pump set up.
 

ktmoutfront

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External pumps are so loud. Can you do brace on the one you have? Maybe something that snaps onto the return tube and runs down on the face of the gauge sending unit bracket.
 

mrk5

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I think I could use the sender I have now. I'll need to see if bending that tube created a kink. I had kinda put that out of my head thinking it would be messed up trying to bend it straight, but since it bent back so easy it might be okay.
 

Truckman4life

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You could always cut off the tubes below the top and use some better stainless tubing and compression or Swagelock fittings to do your own. This is just an example on a Ford tank conversion. Skip through a ways.
 
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