C4 Corvette fuel starvation fix

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Basement Paul
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Joined: Sun Jul 17, 2005 9:27 pm
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C4 Corvette fuel starvation fix

Post by Basement Paul »

Based on the discussion with WXO, that factory tray I learned is not enough, and tends to come undone over time. Something like this is the fix. I know Andy and I have talked about it, but until now have yet to visualize it. Here's someone's writeup:

No, but it was quite easy once the concept was thought out...

I realized that the return line was pouring fuel in the tank constantly and at the same time the pump was starving when going around corners and even under hard accelleration. When you loose the fuel pressure you also loose the return...so one problem created the other and so did solving one problem fix the other.
The factory windage "tray" (now used to hold pocket change on my dresser) broke away from the tank bottom as do most...I was having a horrible windage problem. I couldn't corner under power at all if the tank was below 1/2.

Not satisfied that the little 1" deep tray was much use AND a PITA to replace back in the tank, I wanted to stick something back in there that would hold enough fuel for at least several seconds running...enough for a long sweeping curve at high speed without slinging the fuel off the pump. 4 seconds is forever at 100+ mph in a decreasing radius turn...hitting the gas coming out of a turn like that and getting nothing....just sucks for lack of a better term.
I picked the LUCAS qt bottle (oil treatment) because it was the right diameter, round, deep (need 5-7"), and petroleum resistant. A common qt oil bottle also works well. (rectangular) Must be able to fit thru the tank opening in the tank top.

I cut the top off so the "well" portion was tall and equal. I cut a slot in a bottom rt edge for the pump strainer to fit thru since that is 3-4" long and will need to sit left-right in the tank. Then I marked approx where the bottle would rest against the return tube assy and stay clear of the float arm. I cut slits at 2 levels and used stainless steel safety wire to tie the side of the bottle onto the return tube and frame. Do not try to go around the whole bottle....just cut it so you're securing the left side to the tube .
This has to hold the bottle over against the tube so the float can never hook an edge or hang in its travel in any way. You might have to cut a slice off the top left edge of the well for float arm clearence if it swings too close. Once started, you'll see exactly what I'm trying to describe...

Then I took a small drill bit, 1/8 maybe, and drilled a couple holes in what would be the rear of the bottle at the bottom so fuel could flow in/out and seek its own level. Insert the whole pump/strainer/float mess in the bottle, making sure the strainer end fits thru the slot cut in the bottle bottom so the end of the strainer is sitting outside the bottle. Secure with the stainless wire thru the bottle and around the return line tube. Orient the bottle to clear the float. Get it tied tight so it does not float around or be moved by sloshing fuel.

I made NO holes in the left or right sides since the lateral forces of cornering might help drain it faster and that defeated the purpose of the design. The holes in the bottom rear allow for the level to equalize slowly. I did not want rapid equalizing anyway,....I would prefer that the 'well' always be deeper than the tank as long as the engine is running. This also serves to keep the bigger trash from getting to the whole strainer...since the strainers end (outside the well) can pull fuel in as well as the portion thats inside the well with the pump. Look at this and try to visualize the way it will be when mounted because the bottle with the strainer sticking out the right edge will be resting on the tank bottom, so you do not want to cause the strainer to be crushed or pinched off when its all bolted down. If done properly the 'well' will be right on the tank bottom and need just a little pressure to get the tank cover plate bolted down...

Oh yeah, the round LUCAS bottle is easier to get back in the tank than the rectangular qt oil bottle...thats why I went with the round well this time....

Drop the whole thing in the tank after double checking the float arm for clearence and secure the pump assembly plate with a new gasket.

I have run hard into a corner with the reserve lite ON and not had the engine stumble from fuel starvation...I installed a new sender assy a few months back, and have not run out of fuel yet, but I have pushed it to where it was reading down to 15 miles left and I put over 19 back in the tank...so I am CERTAIN that I am keeping a deeper fuel level in the "well" than the rest of the tank and that is uneffected by G-forces so far. This well design is part of the fuel pump assy instead of having to attach to the tank bottom where access is difficult and damage cannot be repaired easily.


And here is a different guys interpretation.

-BP
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MostMint
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Re: C4 Corvette fuel starvation fix

Post by MostMint »

We did almost the exact same thing with the Saturn but used a rectangular 1 gallon oil jug since it fit perfectly into a small depressed area in the bottom of the tank. The Saturn did not have problems until you wanted the last gallon or or, since the factory had a large cup around the assembly. We only needed it since we were trying to get 2 hrs from a tank.

The C4 is easy though since you don't actually have to remove the tank to do it.
[quote="Basement Paul"]Is that a mint rocketship on the hood?? :shock:
-BP[/quote]
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