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1989 Crew Cab Tow Rig Build

Overview Gallery Discussion
And for those who care...you can see the way I adapted the factory TBI sending unit to -6AN fittings/adapters.

And then installed the sending unit back in the tank. I ran my lines like this on purpose 2 years ago thinking if I ever had to drop the tank, I could do so easily while still keeping the lines attached to the sending unit. All I do is unbolt the electrical connections to the pump underneath, and then drop the tank. Worked pretty good

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Also changed the fuel filter to a much larger one that I think will be better for more long term. Also, the little one that was on there before was only a 40 micron screen...this one is a 10 micron screen. And from my research, they say on average you should have 100 micron filter for the pre-pump (aka the screen on the in-tank pump) and 10 micron post-pump. So this should work good. Also kept the other filter as a spare too...in case of some other related jam, haha

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Threw some new gas in it and took it for a drive, and everything was working perfectly. Then as I was sweeping the shop floor out, and stood back and looked at the truck and it was looking so dang awesome...it just needed a picture taken, haha

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Kay86K5 said:
And for those who care...you can see the way I adapted the factory TBI sending unit to -6AN fittings/adapters.

And then installed the sending unit back in the tank. I ran my lines like this on purpose 2 years ago thinking if I ever had to drop the tank, I could do so easily while still keeping the lines attached to the sending unit. All I do is unbolt the electrical connections to the pump underneath, and then drop the tank. Worked pretty good

View attachment 268971

View attachment 268972
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Tube Adapter fittings? I got some myself but I haven't fitted them yet to see if they'll match the sender correctly. I know others have soldered fittings on their sender but I feel this is a much better way to do it. Got the same premium tank off rock auto too. Just stacking parts for now. Looks good! :saweet:
 
SpeedlabDan said:
Tube Adapter fittings? I got some myself but I haven't fitted them yet to see if they'll match the sender correctly. I know others have soldered fittings on their sender but I feel this is a much better way to do it. Got the same premium tank off rock auto too. Just stacking parts for now. Looks good! :saweet:
Click to expand...

Just cut and flared the supply and return lines and added tube nuts/sleeves, then a male to male adapter to convert to -6AN. I was never a fan of the soldering technique, and this was pretty easy, however I did have to find a sending unit that had longer "ports" coming off the sender so I could have enough room for the flaring tool to work, but found one easily on rockauto. If using a blazer/burban tank it's easier cause they already have the threaded fittings on the end of the sender, so you just need the little male to male adapters is all. I was actually surprised to find on this 1989 TBI saddle tank that they were normal "hose clamp" style fittings...which meant I had to get a little more fancy with it with the flaring and tube nuts/sleeves.

If memory serves me right though...I think @mrk5 found a sender for a saddle tank that did have the threaded fittings off it...is that correct Scott?
 
I'm still using the hose clamp fittings. :whistle: I used the nicer fuel injection hose clamps. That's the only option at the tank selector valve anyway so I figured why not.

I have surmised that a fuel sender from a 26gal TBI tank would work in a saddle tank but I haven't tested it. That's the only year that had the 26gal tank and TBI sender.

In reality I don't think it would be hard to even modify the more common 32gal TBI sender. I think it would just be a matter of cutting the tubes shorter. Only thing I'm not sure about is the float. Maybe the float could be swapped from the saddle tank sender.
 
mrk5 said:
I'm still using the hose clamp fittings. :whistle: I used the nicer fuel injection hose clamps. That's the only option at the tank selector valve anyway so I figured why not.

I have surmised that a fuel sender from a 26gal TBI tank would work in a saddle tank but I haven't tested it. That's the only year that had the 26gal tank and TBI sender.

In reality I don't think it would be hard to even modify the more common 32gal TBI sender. I think it would just be a matter of cutting the tubes shorter. Only thing I'm not sure about is the float. Maybe the float could be swapped from the saddle tank sender.
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I saw some Ford videos on how people modify their sender when going from the 18 gal rear to 38 gal bronco tank and it's just a matter of extending tubes with compression adapters and then the guy I watched built a new float arm that was all bent correctly and what not to mimic the travel of the short arm. I'm sure it would be just as simple on a Chevy.
 
mrk5 said:
I'm still using the hose clamp fittings. :whistle: I used the nicer fuel injection hose clamps. That's the only option at the tank selector valve anyway so I figured why not.

I have surmised that a fuel sender from a 26gal TBI tank would work in a saddle tank but I haven't tested it. That's the only year that had the 26gal tank and TBI sender.

In reality I don't think it would be hard to even modify the more common 32gal TBI sender. I think it would just be a matter of cutting the tubes shorter. Only thing I'm not sure about is the float. Maybe the float could be swapped from the saddle tank sender.
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Ah, yeah now my memory is coming back...I remember you talking about that. And honestly, cutting and flaring the ends of the sender and using the sleeve's/nuts like what I did wasn't difficult at all. So seems like there are a couple different avenues you can go to accomplish the same thing on a saddle tank. I still think the easiest to get the lines converted to -6AN is using a blazer/burban tank as those senders already have the threaded ends (I know cause my K5's TBI tank is this way), but then you run into the issue of fab'ing mounts to put the tank in the rear plus figuring out how you want to do the filler neck/tube (then running all new lines again all the way back). So no matter which way you go it's going to take work...so pick your poison I guess, haha
 
I'm seriously debating putting a small TBI tank in the rear with no filler so it's only fed by the saddle tanks. Then run the EFI off that tank. Kinda like you did but with a 3rd tank.
 
mrk5 said:
I'm seriously debating putting a small TBI tank in the rear with no filler so it's only fed by the saddle tanks. Then run the EFI off that tank. Kinda like you did but with a 3rd tank.
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Dang :thinking::thinking::thinking:

So dual saddle 20 gal tanks, plus another 25 gal K5 tank in the rear. Put the EP381 pump in the K5 tank with lines to the motor, and just have TBI pumps in each saddle tank hooked to their own switches to pump fuel into K5 tank in the rear. Could have 65 gal fuel capacity...

dang you Scott, now you have me thinking, haha
 
Only thing that would suck is you would have to make sure to fill up one saddle tank full, pump it all to the K5 tank, then fill it up again...but that's a price to pay to be ballin' :saweet:
 
Kay86K5 said:
Dang :thinking::thinking::thinking:

So dual saddle 20 gal tanks, plus another 25 gal K5 tank in the rear. Put the EP381 pump in the K5 tank with lines to the motor, and just have TBI pumps in each saddle tank hooked to their own switches to pump fuel into K5 tank in the rear. Could have 65 gal fuel capacity...

dang you Scott, now you have me thinking, haha
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For me it would be easy to just keep the dual tank wiring like it is. Switch the fuel pump power wire to the K5 tank and pull a different power wire through a switch into the dual tank setup.

I would potentially keep the EP381 pumps in the saddle tanks so that I could feesibly switch the saddle tanks back to EFI duty in an emergency. Big thing is I will need a second fuel level gauge for the K5 tank.
 
Kay86K5 said:
Only thing that would suck is you would have to make sure to fill up one saddle tank full, pump it all to the K5 tank, then fill it up again...but that's a price to pay to be ballin' :saweet:
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Instead of 2 stops at the pump it means 3. 1st saddle tank full, then while filling the second saddle tank fill the K5 tank with the first saddle tank, then fill the first saddle tank. Haha.

In reality I would really only need to do this on big road trips. Most of the time you'd just fill one saddle tank and pump it back to the K5 tank. Maybe the other tank would have fuel in it as reserve, but wouldn't need to fill all 3 every time. Most trips I do really only use 15 to 20 gallons at most.
 
Here is a picture of my new saddle tanks I put into my 1991 V3500. I got all new everything for them. senders, straps, strap insulators, filler necks hose, vent hose, filler neck housings. The pumps I put into them where AC/Delco EP377 (30 PSI max). Since I stayed with a small block with TBI that was the max PSI pump they needed. Those fuel tank frame bolts are b!tch to get at.

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mrk5 said:
Instead of 2 stops at the pump it means 3. 1st saddle tank full, then while filling the second saddle tank fill the K5 tank with the first saddle tank, then fill the first saddle tank. Haha.

In reality I would really only need to do this on big road trips. Most of the time you'd just fill one saddle tank and pump it back to the K5 tank. Maybe the other tank would have fuel in it as reserve, but wouldn't need to fill all 3 every time. Most trips I do really only use 15 to 20 gallons at most.
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I think you're on to something! If I only drove enough no need all three I'd do it but I think the fuel would tarnish in mine b4 I used it hah
1-ton said:
Here is a picture of my new saddle tanks I put into my 1991 V3500. I got all new everything for them. senders, straps, strap insulators, filler necks hose, vent hose, filler neck housings. The pumps I put into them where AC/Delco EP377 (30 PSI max). Since I stayed with a small block with TBI that was the max PSI pump they needed.

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Where you get your filler necks?
 
1-ton said:
Here is a picture of my new saddle tanks I put into my 1991 V3500. I got all new everything for them. senders, straps, strap insulators, filler necks hose, vent hose, filler neck housings. The pumps I put into them where AC/Delco EP377 (30 PSI max). Since I stayed with a small block with TBI that was the max PSI pump they needed. Those fuel tank frame bolts are b!tch to get at.

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Agreed...the frame bolts for the tanks mounts are freaking annoying to get to. If GM engineers had half a brain they would have done threaded inserts or welded nuts on the tank brackets, then all you would have to do is undo bolts from the inside of the frame without having to hold the nut on the backside....but it's not the first time I've cursed vehicle engineers for being dipshiz's. I just love when people try to tell me how smart vehicle engineers are...then I love to tell them how I think they are freaking morons half the time
 
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