Alright, so with the hood secured and the clutch fixed, it was time to tackle this weird power loss issue that came up during the race.
As you might recall, we had a power loss issue during testing, which turned out to be fuel pressure loss and I attributed to the leaking fuel supply line in the fuel tank. Replacing the tank seemed to fix the problem, but during the race something similar came up again.
The car seemed good during some last minute testing, during the sprints, and during the first stint of the enduro. However, in the afternoon/evening of the race (after welding up the clutch) the car would go out on track and after about 15 minutes, the power would slowly start to drop and the engine wouldn't rev past a given RPM, which would become lower and lower.
I was pretty convinced that this was not a fuel issue, since I had replaced almost every component in the fuel system. However, during the race we replaced most of the electrical components that we had spares for, with no effect.
I bought another ECU on craigslist (mentioned above) and tried that a couple weeks ago, and it had the some issue as well. So, running out of other options, I decided to put a fuel pressure gauge back on the car and see if this was the problem again.
I tapped the end of the rail and installed an old gauge on it, as such.
Then I mounted a GoPro on the front bumper and with the hood off, went out for a test drive. After about 15 minutes, the issue came up and I brought the car back home. Review of the video showed that it was, in fact, loosing fuel pressure still!!
For your entertainment, here are some short clips of the gauge during that test drive. First, what it's supposed to do: about 35 psi under vacuum and about 45 psi at WOT.
http://youtu.be/oDK05XbGdMs
And here's what was happening after driving around for 15 minutes: about 35 psi at idle, but at WOT the pressure quickly drops from 45 psi down to 10-15 psi, at which point the engine cuts out.
http://youtu.be/vrh1bsDzdDA
So, at least I figured out what was happening. But, I wasn't sure why this was happening. After mulling it over for a while I decided that it wasn't the pressure regulator, which had been swapped out, or the fuel filter, which was new. I decided that it must be a problem with the pump itself not putting out enough flow after running for a while, and that must be either a problem with the pump itself, or the wiring to it.
I left the fuel pump on for about an hour or so after taking this video, then measured the voltage at the fuel tank bulkhead and it came in at 12.1 V or so. So, I decided that this was all probably an issue with the pump itself, which aggravates me because it's a brand new Bosch (supposedly) unit.
This evening, I popped out the pump (getting quick at this too, just like the transmission).
Everything looked fine, though there were some little metal shavings stuck to the body of the pump.
I went through my stash of fuel pumps and found a couple possible candidates - a Walbro 255 and a Denso unit from a '00 Lincoln Continental (just under 300 hp, factory). The Walbro didn't really fit the mounting setup, so the Denso went in. I was also hoping to put on a bigger strainer (had a nice one from a WRX, pictured), but it was a slightly different size, so I rinsed off the one from the Bosch pump and used that again.
That's all back together now and I ran the pump for about 10 minutes with no issues, so I'll take it out for another spin soon and see if this finally fixes the problem.