WOW. I’m stunned. No words. This thing is cursed.
So I have an explanation for my weird fuel and startup issues and it’s such an incredible story I feel the need to share it. There are nuggets of knowledge sprinkled herein but most of it is just me sobbing at this point.
So a few people know, most don’t, but I had entered the car into the La Jolla Concourse d’Elegance this weekend (I should be in the car driving over as I type this).
But I’m not.
Rebuilding the fuel system in my car was prompted by several factors, one of which was wanting to delete the Bosch 044 pump from my setup, another of which was to get the car ready for this show. I’ve been busting tail trying to piece together and troubleshoot this new setup and it seems like every which way I turn I’ve been met with some type of bad luck. So let’s start …
There’s something about the Bosch 044, that when you have it plumbed into your system and prime the pumps it’s able to maintain system pressure. I originally thought it was because it has a built-in check valve – it must be secondary to the check valve typically included on the discharge side, genuine or knock-off. Anyway, after setting up my new fuel system I noted that it wouldn’t hold pressure after the pumps cycled. The only real fluid side changes I made were to delete the Bosch and surge tank, replacing them with the integrated FiTech unit. So the only real change is that the HP pump is no longer the Bosch (I don’t think the surge tank makes a difference, it’s just a big container with lines coming to and fro). So … I figured well crap, the Bosch can hold pressure because it’s got a check valve and this new pump doesn’t. OK, time to search for a check valve. Being in CA, apparently some check valves are OK for sale here and others aren’t – and of course the local race supplies place that has everything hydraulic you can imagine doesn’t carry check valves!
In the meantime I had figured out a way to crank the engine *JUST* as the pumps primed and hit 60 psi and the engine would finally turn over and idle. WOO! Only problem is, I didn’t have any throttle control. None. The ECU wouldn’t respond to throttle input. I scratched my head on this one for a while but someone on the GT40s site mentioned 9/10 times weird things like this happen, it’s the battery. I had purchased this battery almost 2 years ago and it’s been abused pretty badly throughout the build, being discharged and left for dead for months on end. Charging the battery seemed to help the car start so I decided to purchase a new battery just in case. The replacement did seem to address the weird throttle issue I uncovered, sweet – one thing “fixed” and it’ll give me peace of mind knowing the battery is fresh.
OK – back to the fuel system.
So I ordered a Vibrant Performance check valve, thinking that it was a brand name valve and it ought to work right? WRONG. The check valve didn’t do jack. I installed it and pressurized the system and pressure just bled back down like I hadn’t done a thing. I removed the valve and blew through it in both directions – it didn’t make a difference. I cracked the valve open and the internal is literally a rubber flap covering a hole. I’m sure a fart could have blown through the check. D-day for the show was 4 days away so I Amazon Prime’d my ass the next best thing – an obviously Chinese manufactured no-name check that had positive reviews. I’d have gone the Jets or Summit route but I needed it right NOW and I couldn’t stomach paying $30-40 for shipping alone. The valve arrived and holy smokes, it looks good! I could see a metal structure and a spring by looking down the opening – great, this is the kind of positive sealing I was looking for!
Install the valve. Nothing. Nada. WTF. I had installed it in the INLET side of my fuel pressure regulator. You see where this is going right? Yeah, so the fuel pressure regulator doesn’t explicitly have a check, but by the very nature of what it does, it’s a check valve. It stays closed until it hits the desired hydraulic pressure then the diaphragm inside cracks open to bleed pressure – but only enough to bring it down to whatever it was set to before seating again. Well … at this point I supposed that my fuel pressure regulator was on its way out. The diaphragm is damaged and the check wasn’t doing jack because all the pressure was bleeding out through the return port. OK, I’m going to jury rig this thing so I can get the car to the show then we’ll fix it later. See where this is going yet?
I move the check valve over to the OUTLET side of the fuel pressure regulator and wouldn’t you know it? I prime the pumps and pressure on the gauge bleeds down, but this time the engine starts running when I crank it! A-Ha, so the check is actually working, it’s really maintaining rail pressure, and the engine is starting now – WOO!
**UPDATE: Yeah, if you’re going to install a check valve in your HP fuel system, put it BEFORE the fuel pressure regulator so it can bleed down fuel pressure after the engine is shut off. With the check valve placed after the regulator, fuel trapped in the rail will over pressurize the system once the engine is shutdown and everything gets heat soaked – the fuel will expand as it gets hot and there’s nowhere for that pressure to go.
Except the engine doesn’t want to keep running.
Thanks to HJones, it hasn’t been since college that I’ve had to think about Ohm’s Law, but he reminded me about voltage drop across components in series and in parallel. It didn’t occur to me to think about this until I pulled out the voltmeter to figure out why the car was having issues staying on. As part of my redesign effort I wanted to take the load off the fuel pump wire coming from the fuse box; previously I had run both pumps off the single wire, splitting it just before getting to each pump. That worked fine because the pumps were wired in parallel and both were seeing a full +12V. In my new setup I used that same wire to serve as a signal wire, running it through 2 relays IN SERIES. Once tripped, they would draw +12V from a nearby junction block; one relay per pump. So … every time I cycled the engine to prime the pumps they would run – because the battery had *just* enough voltage that the relays would trip and power the pumps. It must have been on the very edge of when the relays would trip because I could drive the car around for a bit then it would randomly quit – likely because the relay running to the HP pump tripped open, shutting the pump down. OK – figured that out, I’m going to hard-wire the pumps to my kill switch, I’ll re-wire the relay setup later. SWEET.
The Concourse show is tomorrow and it’s 5PM. I’m tired and frustrated but at least I’ve finally gotten it put together enough that I can drive it and enjoy a day at the show, looking forward to finally driving this car – it’s been about a month since the car died on me and I embarked on this whole fuel system re-do thing. If you haven’t already watched it, here’s a video of the exact moment the car died – YouTube link.
OK, check valve in, getting 60 psi at the fuel rail, fuel pumps hard-wired, I got everything I need to limp this bitch to the show before I have to get back into it and address the regulator and wiring. I took the car out for a ~20 mile drive just to test things outs. GOD it feels good to drive the car again! I’m having a ton of fun but I notice my rear view monitor is flickering. It would go out intermittently. Hmm… bad connection? Weird, I didn’t touch any wires in my ceiling or behind my dash panel. Keep driving … sometimes I instinctively go to push DOWN on my lift because I’m paranoid that I haven’t fully dropped the car and I just happened to do that – whoa, weird, my monitor just went out again. Monitor comes back up after a few seconds. Hit the lift pump – monitor goes out. WTF? How the heck could they possibly be related? They’re on totally separate circuits.
Uh-oh … cycle over to the diagnostic screen on my AIM dash and system voltage is low. It’s in the 12.X which is unusual, it should be 13V+ with the alternator spinning. OK, bad battery (I LITERALLY JUST REPLACED THIS 2 DAYS AGO!!!), bad alternator (I LITERALLY JUST REPLACED THIS ~200 MILES AGO!!!!), or blown fuse (from the alternator to my battery). Damn, I’m about 8 miles from home, take it easy but at this point I know the clock is ticking. I turn everything I don’t need off – fan, fog lights, radio – lol, not much else in the SLC that can use power! By the time I pulled into my driveway my battery voltage had dropped low enough that the rear view monitor was dead (it has a safety feature that shuts it down below a certain voltage) – but at least I made it home! OK, open up the back and wouldn’t you know it? The fuse between my alternator and battery had blown. WTF. I don’t know what could have possibly blown a 50AMP fuse. I checked the connections between the alternator and battery and everything looks good. No short. All my vehicle loads are going through the kill switch so the only thing between this fuse is the battery and alternator. Father-in-law thinks it’s a defective fuse. I’m putting this in the “Future nightmare to come” category for now.
It’s 3:30AM, day of the show. I didn’t sleep very well and now I can’t get back to sleep. Gates open at 6AM and it’s 30 minutes away. I’ve got another hour and a half of sleep to go but I’m nervous. I don’t like driving the car all janky rigged like this but I made a commitment to bring the car to the show and want to follow through. Lay in bed for the next hour and a half and it’s finally time to load the car. Get everything loaded … I have to play musical cars and I don’t want to wake my neighbors. Starting the SLC is going to be a commotion so I decide I should start the car up with the garage door closed then take off as quickly and quietly as possible.
Car packed. I’m ready. Flip the kill switch, pumps whirr to life. Let’s go!
Except we’re not.
Engine cranks cranks cranks, nothing. WTF.
I wanted to cry.
Open up the back of the car and look at the fuel pressure gauge. 20 psi.
I typed that twice, it’s not a typo. My eyeballs aren’t wrong. Gauge reads 20 psi with the pumps running. Pull out the voltmeter. Yep, +12V on both pump terminals. Touch all the lines. No fuel leakage. 20 psi. Pull out the wrench and adjust the fuel pressure regulator. NOTHING. 20 psi. Turning it one way or the other and the pressure is constant. 20 fvcking psi.
That’s it. I realized the diaphragm must have let go overnight or as I tried to start the car. 20 psi must be the non-regulated restriction with a fully blown open fvcking regulator. Can’t blame a knock-off for this one, it’s an Aeromotive unit I purchased from Summit.
I left everything in the car, turned off the garage lights, and sat down to type out this miserable accounting of my last few days. It’s a good thing I did, I can see the humor in everything now. As they say, writing can be cathartic.
But I’d rather be driving my SLC.
**Update 4/15: So I had some time to cool off and I started diagnosing the fuel system. Turns out the issue didn’t lay with the fuel pressure regulator, it’s with the new FiTech pump. There’s some kind of internal failure; the gauge now reads ~8-15 psi with the pump running. Allan/Zakari3030 experienced a similar issue with a FiTech surge tank/pump in a prior build and discovered the internal feed tube had been broken. I’m done, this setup’s going back and I’m staying far away from any FiTech products from now on. You can’t make this stuff up!
Stay tuned for details on SLC fuel system v3.0 …