My Ongoing Mid-Life Crisis

A

aaronc7

Greenie N00B Member
Getting ready to do a few upgrades, figured I would make a little thread. Mid life crisis in its current state:

2003 Corvette Z06
53k miles
Forged "LS6" with EPS 226/230 .600" cam, ported 243 heads
Kooks LT headers, off-road X-pipe, stock Ti exhaust
Monster LT1-S Clutch
Dewitts aluminum radiator/oil cooler
DRM-valved Bilstein shocks
Hotchkis anti-sway bars
Corbeau A4 seats, MGW Shifter

Dynoed right around 440whp/400wtq on a Dynocom dyno after the rebuild.

Anyways, getting ready to supercharge it. I'm going to be moving across the country in a few months, so the big install will have to wait until after that, but in the meantime I've been doing all the planning and doing little stuff that makes sense as I can.

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Today I finished swapping the

fuel pump, which was a pretty big pain in the ass. You have to drop the tanks and it's right around the exhaust/transaxle so there is no space to do anything and reaching this damn 'crossover' tube disconnect collar was the worst. Really no drama with the actual install, fired right up and fuel pressure is right at 58-60psi. It's a Walbro 450, but Lingenfelter makes it into a plug and play unit that retains all stock 'jet pump' functionality that keeps the bucket filled and keeps fuel transferred between tanks correctly. Fucken overpriced, but I wanted easy.

Also I've had a broken gas gauge/reads empty for ages. Super common for the C5s to corrode the fuel level sending units... so I was sure it was that and ordered/installed new ones of those as well. Shit was still broke after the swap so I had to dig deeper. In it's broken state, the fuel level senders were sending 5v signal to the ECU for both tanks, all the time. 0.7-2.5v is normal I guess. I checked the wiring point by point from the back of the car back up to the ECU. I am pretty sure just the act of reseating one of the harness connectors or ECU connector completely fixed the issue, lawl. $100 wasted on fuel level senders most likely, but at least it's fixed finally.

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Midlife crisis indecisiveness continues.

Almost brand new Magnaflow exhaust is in the mail for the car. I had a GHL previously and while it sounded nice, it was a bit too loud and highway drone got annoying. Stock exhaust isn't too bad with the mods I have, but below 4k rpm and normal driving it's damn quiet. Hopefully this magnaflow guy is a nice happy medium.... we'll see.
 
new balance is the shit man
[doublepost=1535159891][/doublepost]Magnaflow exhaust install complete. Overall happy with it. Looks good, tips are a nice size, not too big not too small. Sound is very smooth and deep tone. A little different than some of the more popular systems like Corsa and the GHL I had before which are a bit more 'raspy' sounding.

One of the reasons I got rid of the GHL was bad drone at certain RPMs. This one does have some and it's at exactly the same RPMs.... I think with my current mods there is just probably no way around it. Even the stock exhaust droned at the same RPMs, but it was just so quiet you couldn't really hear it. This is a happy medium that I can live with.

Here's a pic, maybe I'll get a video one day.

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Part 2 of fuel pump swap.

Of course I had to have some sort of fail..... it just didn't feel right having a totally smooth project with no issues.

I did a decent amount of idling in the garage with the new fuel pump waiting for the exhaust to arrive. Not a single issue. Drove the car to the gas station to fill up... car would not start. Thankfully I brought my datalogger with me so I could monitor live data and log for later review. I had no fuel pressure and it was hard to tell for sure due to ambient noise but pretty sure the pump wasnt running when 'key on'.

Fuses were good and I swapped the horn and fuel pump relay and lo and behold it started up.... but the horn also worked. Fuel pressure was still dropping/fuel pump cutting out intermittently, sometimes stalling out the engine if I was at idle. Did it a few times while at speed and it would die, then magically come back to life. For the most part though, 30+ mins of driving, it was flawless once it got going.

Next morning, started.....then died, twice. After that it fired right up and I drove to work/back all day no issues. Back in the garage last night I was pulling/reinstalling/swapping relays and sometimes the fuel pump would prime, other times no at all. Narrowed it down to some sort of wiring issue in or below the fuse box itself where the relay plugs into.

At this point 99% sure one of the relay pins for the pump (on the fuse box side) got pushed down/widened out and is just not making good consistent contact with the relay, whatever relay I use. I confirmed this by making a jumper wire basically and testing each pin.... 3 are very snug and tight, one is very loose, no resistance at all.

I spent a few hours trying to make apart the top portion of the fuse box... long story short, it's not worth the effort on this car and I'll probably break the thing. I already did a temp fix (not road tested) by adding a little solder to the loose pin to make it snug. I feel like this is only going to make the problem worse though by widening the gap even more. Probably fine if I never pull the relay again but any sort of removal/reinstall is just going to make it worse and worse.

Replacement fuse panel is like $100, not too bad all things considered. But I already purchased an upgraded wiring harness for aftermarket fuel pumps (not yet installed). It uses the factory fuel pump power line as the signal to trigger another external relay to power the pump directly off the alternator. I am thinking I should be able to actually bypass the whole factory fuel pump fuse/relay and use the original pump trigger wire to trigger the new relay now instead. I just hate this like this because I gotta start cutting some factory harness wires and if it doesn't quite work out, shit starts getting hairy lol.

Datalog of the fuel pressure. Top chart in green is fuel pressure.

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[doublepost=1535223785][/doublepost]Well I went thru with my proposed mod to utilize the aftermarket fuel pump harness that I already had on hand and modify the stock harness to completely bypass the factory fuse/relay for the fuel pump. The aftermarket harness just uses bigger gauge wire and connects directly to the alternator to supply more volts/amps to the fuel pump and supposed to handle the increased load of larger fuel pumps / boost a pumps.

Here's the factory wiring, pretty standard

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Here's with the aftermarket harness installed. It just takes the factory relay output as the signal to turn on it's own separate relay to turn on and power the pump directly.

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My proposed mod... connect the ECU/PCM fuel pump trigger output directly to the new/aftermarket relay.... connecting a green and grey wire under the fuse box.

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Done... no turning back now

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Happy to report that I think this cured the issue 100% and confirms that relay contact was the issue the whole time. Sigh of relief for now.

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Nice project. Buddy of mine and his wife picked up 17 Grand Sports. He has the glass top in blue and she has the dark cherry convertible. They already have a 80 and a 95 pace car. I’m trying to convince him to do some upgrades. :)
 
Well, my move is complete and settled in to where I can get back into the build.

Went to local mustang dyno to get a good baseline run to account for different dyno and elevation change. I don't have the plot, but it made 350whp uncorrected or 405 SAE lmao. Lost about 60-70 hp from the elevation gain and the rest just differences between dynos.

I jumped on a black friday deal and ordered the kit. Should ship next week or early week after. Vortech V3 Ti-trim with a secondary/direct drive 8-rib belt setup and pulley combo to basically max the blower rpm out by 6500 engine rpm. I am hoping for mid 600s at this elevation... we will see. I have that elevation and 91 octane fuel (and meth) possibly holding me back.

Will be jumping into the install as soon as I can, realistically probably won't be done until after christmas, but that's ok, going to take my time.
 
Are there 2 in tank pumps? I'm confused by the pick you show the lingenfelter basket. Looks like 2 pump assemblies in the surge tank looking things hooked together
 
Corvettes have a split tank that straddles the driveshaft. I believe one pump just pushes fuel to one side and the other pump supplies the motor. Or I completely misunderstood your question
 
EB is more or less correct, just technically the driver side pump drives the fuel transfer as well.

The driver side tank contains the fuel pump. Within that same bucket, there is a 'venturi' pump which constantly siphons fuel from the passenger side to driver side. So at 1/2 tank on the gauge inside the car, the driver tank is full, passenger completely empty. The passenger tank contains a 'bucket' but it's purely purge valve related and just a level sensor.
 
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