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

[mrk5]

It does not work... I suppose if you wanted to shorten up the sending unit tube, find a different fuel pump that can be adapted, and use some fittings you could but I'm giving up on the idea.

That's kinda what I was thinking would have to happen. I was just wondering if anyone made an in-tank pump with AN fittings. Seems like the sending unit could be modified to work fairly easily.

Bung and external pump

Miniwally mentioned this at one point and it actually could work work fairly well in the saddle tanks. IIRC the frame angles up somewhere just past midpoint of the tank and you could get a bung in the bottom of the tank there. Protect it with a little plate and it'd probably be good to go. I've just been stuck on trying to stick with the internal pumps.

If that route was attempted I would try to use a single external pump and pull fuel through the selector valve. If the old mechanical pumps could do it, surely an electric pump can especially with a bung on the bottom of the tank.

I also looked up fuel tank sizes. The 25 gallon and 31 gallon tanks have the same "footprint" the 31 gallon is 2" deeper. The reason the 40 gallon won't fit is because it is 7" longer than the 31 gallon tank. It's also another 1" deeper.

 

[Bent77]

Been pondering using a 25 and keeping the drivers side as a transfer

 

[mrk5]

Been pondering using a 25 and keeping the drivers side as a transfer

I did a quick search and didn't find the 25gal with a baffle tray, FWIW.

 

[Bent77]

Haven't seen anything about the baffles. Also no sure how critical it is on a square tank, since at almost any angle the sump stays covered until under appx 1/3 of a tank. I've never used that much even during Snowmaggedon

 

[sweetk30]

87-up tank for efi with baffle

 

[Bent77]

That was what I figured though it doesn't specifically say so

 

[mrk5]

Gastanks.com didn't list a 25 gallon tank for 87-91 trucks. Didn't think to look at LMC.

 

[Bent77]

I'm not smart enough to look somewhere else for stockish parts

 

[ZooMad75]

I got an efi burb tank in my way. I'm not sure if it's a 31 or 40 gallon. It's yours if you want it. I can deliver too. Sometimes the best way to see if it fits is to see if it fits. You know you got to visualize it.

 

[Bent77]

I got an efi burb tank in my way. I'm not sure if it's a 31 or 40 gallon. It's yours if you want it. I can deliver too. Sometimes the best way to see if it fits is to see if it fits. You know you got to visualize it.

Was that directed at me or Scott?

 

[ZooMad75]

Was that directed at me or Scott?

I should have specified, but since it was Scott's thread I meant it for him. However, if Scott don't want it, it's yours. I'm tired of always moving it out of my way. I'm coming up to Denver this weekend. If either of you wants it I'll throw it in the back of the Blazer.

 

[Bent77]

Well either way I can grab it from you if you're up in Arvada Saturday. If Scott needs it, I'll be a lot closer

 

[ZooMad75]

Well either way I can grab it from you if you're up in Arvada Saturday. If Scott needs it, I'll be a lot closer

Sounds good to me. Yep, I'll be in Arvada sat afternoon and Sunday. I'll load it up.

 

[mrk5]

Funny @ZooMad75 mentioned this because that's exactly what I was thinking; you almost need to have a tank to test fit to decide if it's worth trying to buy a tank. @Bent77 can use it because I'll know how it would work in mine based on how it works in his. It'll be a little trickier for me to commit to test fitting it because I'll have to get the tailpipe out of the way.

if I do go with a K5 tank, I was thinking the big muffler I have is quiet enough I could probably get away with directing the tailpipe out in front of the rear tire. Ideally I'd pull it over to the passenger side, but don't know if it would clear the driveshaft.

 

[skunked]

is the longbed 7" longer than the shortbed behind the rear axle? There's your answer.

I should also note that I found some witness marks on my diff cover from my gas tank skid plate. Being fully loaded with gear and compressing the rear axle is the cause.

 

[Bent77]

Just self clearancing

 

[Bent77]

is the longbed 7" longer than the shortbed behind the rear axle? There's your answer.

I should also note that I found some witness marks on my diff cover from my gas tank skid plate. Being fully loaded with gear and compressing the rear axle is the cause.

I think some of both. 14" difference in wheel base?

 

[brokenparts]

I did more research... the hydramat (#16-111) that I pictured earlier will work with this intank pump or any intank pump with a 11mm OD inlet.

Just wanted to update in case someone was researching info.

 

[mrk5]

is the longbed 7" longer than the shortbed behind the rear axle? There's your answer.

I should also note that I found some witness marks on my diff cover from my gas tank skid plate. Being fully loaded with gear and compressing the rear axle is the cause.

I think some of both. 14" difference in wheel base?

I think they are 117" & 130" for the 2 wheelbases. So a longbed has about 13" in front and 11" in the rear versus a short bed.

My concern would be how the cross members work out. I have one at the back that is basically just over the receiver hitch. That's the one I think could be different and pushes the tank towards the axle. I also think this could be where the differences

 

[mrk5]

You all think it would work okay to put the 4l80e on my engine stand? Or is that too much leverage on the aluminum bellhousing?