[73LeMans]

Since the temperature gauge wasn't gauging, and I was waiting on the new one to arrive, I wanted to make good use of the one day a week I work on this thing, so I decided it was a good time to wire in my fancy new Aeromotive Fuel Pump Speed Controller.

Behold its beauty, but don't stare at it too long!



Ooohh.... ahhhh.


This wasn't part of my original fuel system plan, but the more I thought about it, the less I felt I could do without it. It makes sense; keep the pump running slowly until you need it, and keep the fuel from needlessly circulating and taking on heat, all the while prolonging pump life. Win, win, win. Lets face it, this car will see more time cruising at 40mph, then it will ever see wide open.

Probably best to start with a tip.

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Tip#16 Read instructions. When done reading instructions, look for any tech bulletins or troubleshooting tips for the item you're trying to install before actually installing it. This way you can know the entire scope of pain on which you are about to embark.
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This one had me almost throwing tools. (OK, maybe some actually found their way to the other side of the garage)

Before installing, the question arose of whether or not the relay in the pump circuit was needed anymore. Reading a bit of the marketing on the company site with regard to this controller, it states "A solid-state transistor circuit, rated up to 40 amps, replaces the relays recommended in most fuel pump electrical circuits."

This is good and bad. Good that I can use the pump power and ground wire already running to the relay on my electronic board in the passenger footwell, but bad that I spent $100 on that relay "kit" that is now rendered useless. (Another reminder of why its best to plan the project 100% ahead of time)

Wiring now is pretty straight forward. Splice into the MSD tach signal, interrupt the pump power supply circuit as mentioned, ground it and you're pretty much there.

Oh yeah....and you gotta make a mount. I did that with some flat stock and bent it to an angle I thought was acceptable. I left it open toward the top to allow the wires a place to dive into. I mounted it upside down for two reasons -

- I hate wires. The less I see of them the better. With 7 on this crazy thing, best to get them out of sight quickly.
- Easier to see the LEDs from the drivers seat

I like it -





I test fired the pump and sure enough, you can clearly hear it cut the speed when its not seeing any RPM signal. Cool. Fire it up and the car actually runs. Imagine that! Now, if only there was a way to keep it from going into default shutdown mode and shutting off the pump after 6 minutes of idling.

#&*( Maybe wiring wasn't so simple after all?

This unit limits pump RPM until a user defined RPM is set, whereas the pump then goes into Full mode pushing 100% of the fuel. Whats happening at idle, is the controller is seeing random false spikes in RPM telling the pump to go to Full for a flash, then not, then Full, then not, then Full etc, at a rate of about 20x a min. This is bad. Ive even confirmed this at the pump with a meter - the voltage is bouncing all of the place with a 1.6 volt range. To protect the system, the controller senses the fault, and shuts off the pump.

I'll have to hand it to Aeromotive- they have some good documentation. I just wish the tech bulletins were included with installation instructions. I would have wired things differently from the start.

The troubleshooting Tech Bulletin first mentions cutting down, or getting rid of the electromagnetic interference around the tach signal. It doesn't want you to splice into the tach signal; it wants the signal straight from the MSD and then a separate wire run to the tach from there. Ok. Done. No difference in behavior.

It goes on and talks about creating a filter to clean up the EMI on the tach signal. Like I said, Its excellently written so even a monkey like me can get it done, but I shudder at the mere mention of things like capacitors and resistors and all those other crazy electrical thingamajigs I never want to know anything about. I'm going to skip this part, and take the tach out of the equation by disconnecting it altogether. Same problem, but altered such that voltage fluctuation @ the pump is only .3V. Better, but the pump still shuts down.

Not sure whats going on exactly. The ground circuit for the pump and controller has 1.6 Ω resistance, connections are tight and all the crimps are good. Min volts on the controller is set to 8 volts and we never dip below that during cranking or running. Granted the charging system is not quite up to snuff yet - I'm only getting 13.6V at the battery - but never am I below 11 for any period of time.

I'm just going to leave this one up to folks smarter than me. I think its the unit itself, but then again electricity hates me, so maybe its the wiring. I've reached out to Brett @ Aeromotive and will keep you apprised of the outcome.