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31 gallon tank same for sub and K5?

I lucked out junkyarding today. I found a '90 Blazer that had been in a wreck, but driven to the yard a week or two ago. It even had like 90% of the interior still in it. I bought the tank, sending unit and all of the fuel lines from the tank to the throttle body. I plan to use the rear flex lines and the hardlines as-is. Then the frontmost lines are part hard and part flex. I'm thinking maybe I can cut then and extend them with some universal brake/fuel lines. Before that, I will ask a guy I know who does lines professionally if he can do something slicker that doesn't involve compression fittings.

I don't know yet if the baffle is still intact. I was thinking, though, that a lot of trucks must drive around with this condition. What is the consequence? Fuel starvation?
 
After an acid soak (this is Michigan, after all), I got the sending unit out. The baffling is steel and everything inside looks really clean. As a bonus, I used the TBI pump to empty out about 2.5 gallons of gas that I can run in my lawnmower.

Anybody need a used TBI fuel pump? It has good flow.
 
Any chance you can get a pic of the steel baffle?

I know what the plastic stock ones are like, and I know that the steel one in the aftermarket tank is a different design, curious exactly whats going on with the steel ones you've found.

You Camaro TPI'ing this?
 
I have some pictures, but I have some hardware problems, so I can't post them yet. The tank says "Spectra Premium, Made in Canada, GM 14C" on the bottom. I guess that makes it this one: http://www.pennswoods.net/~wec/gm/blazer_fullsize.htm

I can't tell if the sending unit and pump are factory or aftermarket.
 
OK, that makes sense then. Guess with all the rust back east, replacement tanks are pretty common. (sounds like it)

I don't necessarily like the steel baffle in my aftermarket tank, I don't see how it is anywhere as effective as GM's plastic one. Mine's essentially a square pan in the center directly under the pickup, with a hole or two drilled near the inner edges. The GM design at least didn't let the fuel back out while angled up, down or sideways.
 
How does the factory baffle let gas in, but not let it out when you are off-angle?

BTW: Yes, this will be TPI hardware, controlled by Megasquirt II.
 
The stock one was a labyrinth...inner box the fuel sat in, with the fuel "passage" being curved around the inner box...the fuel would have to get around 3 90* bends before entering/exiting the sump, so off-angle, the fuel can't get around at least one of the bends. Pretty ingenious, too bad the aftermarket ones I've seen don't repeat that. Pretty deep too, as I recall deeper than the aftermarket sump.

I was just thinking about the fuel lines...Camaro stuff comes off the wrong side to use the stock TBI lines, but Corvettes apparently come off the right(passenger) side. It was painful trying to bend them up straight enough to use, but I managed, along with making a few brackets to hold it solidly. I would have used new lines, but good luck finding bendable sections that long with the Saginaw fittings on the ends.
 
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The stock plastic baffle in my suburban's tank let gas run out faster than the aftermarket tank with steel baffles in my blazer...why? Because the plastic one is broken, cheap and flimsy. I guess 17 years is a good life span, but I am happier with the steel.

BTW, my sub had a 35 gallon tank. Not as deep as the 40, but longer than the 31 (too long for a blazer).
 
But how is the aftermarket one constructed? That was my problem, perhaps Blue can clarify if his look the same...holes drilled in the bottom of the sump do nothing to keep fuel in.

Yes, the stock ones material sucked, but the design was simple and very effective. My steel one sucks in comparison, even though it won't break. Poor trade off IMO. :(
 
The sump in my blazer tank has two holes in the bottom. But, the size of the holes are such that the gas does not empty really fast. They are small holes that only allow the fuel to drain slowly when the truck is at extreme angles.
 
Exactly. It just takes a while to empty the sump.

For the plastic ones, with the plastic trapping the fuel from escaping, that also means that it's hard to get more fuel back in there. I wonder how much fuel is trapped in there and how long it takes for the pump to empty it. Let's say you are stuck in a hill climb or off angle in a water hole and have to idle and/or rev the engine for a long time. The problem is especially bad if the tank is low to begin with.

I suppose the metal ones are designed primarily for braking, acceleration and cornering. Probably the best-bet for off-roading is to have a lot of fuel in the tank when you start off.
 
Well, the same can be said of the steel sump as well. :)

Either there has to be enough fuel to submerse the sump to enter, or, if fuel level is below the top of the sump, it will have to percolate back into the sump on flat ground. Not to mention, at least on mine I think the sump is only 3 or 4 inches deep. Hard braking or bouncing I'd think would slosh fuel right out of the sump. All while it's draining through the hole(s). :)

The plastic setup, once you hit level ground, fuel is almost immediately at the same level in the sump as it is in the tank since it will flow better than a couple of small holes.

Keeping a full tank is obviously key, I just wonder how these sumps really perform. I guess I'll see next time I'm out in the woods, as I usually stretch out the fill interval below 1/4 tank often.

Now what was the question? Sub tanks the same as K5? lol
 
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