29 Mar 2013

Stop-nuts were put on the brake and clutch master cylinder shafts, removing one variable from what could be causing the shifting clutch engagement point. After thinking it through, it seems unlikely that it’s “the clutch needs to wear-in.” That would make it engage further from the floor, not closer. A leak in the system would be… well, a leak, but the system shows no sign of that. A buddy suggested that maybe the clutch master cylinder itself is defective, with fluid leaking past the piston. Maybe, but where’s it leaking to? I’d expect to see external evidence… unless it’s getting by the piston and returning to the reservoir instead of doing its part to push the clutch in… hmmm. That could be it but we’ll wait and see if the check-nut fixes the issue – I hope so but am suspicious.

Recalibrated the fuel level sensor. The tank was drained by disconnecting the fuel return line and pumping the gas into a container until bubbles appeared. That’s a far more realistic version of “empty” than what CAD calculates. With empty established, readings were taken (with the engine running to stabilize the voltage) as one gallon at a time was added. What’s unclear is exactly how far the tank can be filled since the fuel filler pipe and safety-reversion float from the Miata were used. The bottom of the filler assembly dictates the amount of fuel that can be added before the fuel vent has to deal with it. I got to 12 gallons and the tank started making burping noises so things were stopped there, counting on the math equation to work if it’s filled further. I’m not sure what will happen if I over-fill it such that there’s standing pressure on both the fuel level sensor and Miata vent assembly (not sure what it does.) I don’t want to be at the gas station and have it spit back out the filler, or suddenly see gas dripping under the car…

I made the judgment call to route returning fuel from the engine to the main accumulator section in the tank. That seemed to make more sense then having the tank do its part with its mouse doors to get the fuel near the pickup, only to have the fuel returned elsewhere. This way it keeps that section as full as possible, but I may be over-thinking it; perhaps the fuel has something else up its sleeve and won’t follow my imagined rules. The point of mentioning this is that even though “empty” was established, the section from which the fuel is drawn will be kept more full, so even when the tank indicates empty there should be time to high-tail it to a gas station.