Any good MFI people out there?

[LeafGreen]

Grady,

Funny you should mention muffler...I started noticing an exhaust smell inside the car one day, and upon investigation, I quickly found that the muffler seam was leaking in three places, two of which were near the fresh air hose inlet. Wondering how this could have happened to a new muffler, and knowing all the fuel delivery problems I have been having lately, I started putting two and two together.

One of my problems was backfiring out the exhaust - but not those girly-man backfires, I mean 12-gauge shotgun style followed by a big cloud of black smoke. Well, lets just say a few of those explosions are enough to find any weak links in the muffler seam. I repaired the muffler by pop riveting and torch brazing the seam - good as new! I suspect the backfires were a result of excessive fuel vapor building up in the muffler and being ignited by hot exhaust gas when the mixture reached stoichiometric. Anyway...

I have been checking many details regarding the fuel system, some of which are shown in the pictures. See my cheeezy protractor set up (no laughing) which took about two hours from conception to implementation. The result? It was about .5 deg out of tolerance. I double checked the pump rod setting at 114 mm, adjusted the throttle rods to pick up when the pump lever moves and re checked the angles - checked OK. This minor correction made a noticeable difference in driveability. By the way, the pump S/N ends in 015, which as I remember, is the correct pump for my car.

So far the biggest improvements have been solving the over rich condition brought on by the leaky cold start solenoid and proper shimming of the thermostat. I am now fighting the idle CO and main rack adjustments - I believe you mentioned there is a proper “balance” between the two adjustments. Is there a good rough starting point for both adjustments? Something like: turn rack adjustment fully CW and back off “x” turns.

According to my CO meter (if I can trust it), the high end is rich (8-10%+) and the idle can be adjusted to around 3% without trouble. The measurements are taken in a no load situation holding the engine at 3 or 4KRPM, and I have yet to see the desired 2-3% CO at that RPM. Adjusting the rack aggressively toward the 2-3% number results in very weak performance as measured by the seat-of-the-pants dyno and also leans out the idle mixture. I have noticed that one or two clicks on the rack toward lean (CW) must be followed by 3-4 clicks rich (CW) on the idle CO screw. By shifting these adjustments slightly, I have made progress in eliminating my off idle stumble and further improving driveability. The car runs pretty strong and doesn’t seem to use an excessive amount of fuel (~20 MPG).

[LeafGreen]

As promised...Thermotime switch wiring detail, see picture (number 14). The picture is out of the factory manual and the following description is my interpretation of how it works. Please correct me if I'm wrong.

The "G" terminal (to starter and # 52 relay coil) and "W" terminal (to # 52 relay coil) connections must be observed. Looking at the thermotime switch schematic, the "G" terminal goes to ground through what appears to be a resistance heater (thermo) and the "W" terminal goes to ground through what appears to be a bi-metallic strip (the switch). Current flowing through the resistance heater during cranking causes the bi-metallic strip to heat up, and after a certain amount of "time", the bi-metallic strip breaks contact interrupting the current flow to the relay coil (# 52) and cuts off power to the cold start solenoid (pictured directly above the cut out solenoid # 13).

[LeafGreen]

...Finally, the speed switch replacement parts diagram. Note: The new transistor may look different, but its function is the same (make sure the orientation of the new component matches the original). Failure analysis of my unit was easy - obvious damage brought on by corrosion.